Tire

TireFrom Wikipedia, the free encyclopedia Jump to: navigation, search This article is about tires used on road vehicles. For railroad tires, see railway tires. For other uses, see Tire (disambiguation). Stacked and standing car tires A tire (in American English and Canadian English) or tyre (in some Commonwealth Nations such as UK, Australia and New Zealand) is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground. The word itself may be derived from the word "tie," which refers to the outer steel ring part of a wooden cart wheel that ties the wood segments together (see Etymology below). The fundamental materials of modern tires are synthetic rubber, natural rubber, fabric and wire, along with other compound chemicals. They consist of a tread and a body. The tread provides traction while the body ensures support. Before rubber was invented, the first versions of tires were simply bands of metal that fitted around wooden wheels to prevent wear and tear. Today, the vast majority of tires are pneumatic inflatable structures, comprising a doughnut-shaped body of cords and wires encased in rubber and generally filled with compressed air to form an inflatable cushion. Pneumatic tires are used on many types of vehicles, such as cars, bicycles, motorcycles, trucks, earthmovers, and aircraft. Contents       1 Etymology and spelling 2 History 3 Manufacturing 4 Components 5 Associated components 6 Construction types            7 Specifications 8 Performance characteristics 9 Markings 10 Vehicle applications 11 Sound and vibration characteristics 12 Regulatory bodies 13 Safety 14 Asymmetric tire 15 See also 16 References 17 External links Etymology and spelling The Oxford English Dictionary suggests that the word derives from "attire",[1] while other sources suggest a connection with the verb "to tie".[2] From the 15th to the 17th centuries the spellings tire and tyre were used without distinction;[1] but by 1700 tyre had become obsolete and tire remained as the settled spelling.[1] In the UK, the spelling tyre was revived in the 19th century for pneumatic tires, though many continued to use tire for the iron variety. The Times newspaper in Britain was still using tire as late as 1905.[3] The 1911 edition of the Encyclopædia Britannica states that "[t]he spelling 'tyre' is not now accepted by the best English authorities, and is unrecognized in the US",[2] while Fowler's Modern English Usage of 1926 says that "there is nothing to be said for 'tyre', which is etymologically wrong, as well as needlessly divergent from our own [sc. British] older & the present American usage".[1] However, over the course of the 20th century tyre became established as the standard British spelling. History The earliest tires were bands of iron (later steel), placed on wooden wheels, used on carts and wagons. The tire would be heated in a forge fire, placed over the wheel and quenched, causing the metal to contract and fit tightly on the wheel. A skilled worker, known as a wheelwright, carried out this work. The outer ring served to "tie" the wheel segments together for use, providing also a wear-resistant surface to the perimeter of the wheel. The word "tire" thus emerged as a variant spelling to refer to the metal bands used to tie wheels. The first practical pneumatic tire was made by John Boyd Dunlop while working as a veterinarian in May Street, Belfast, Ireland in 1887 for his son's bicycle, in an effort to prevent the headaches his son had while riding on rough roads (Dunlop's patent was later declared invalid because of prior art by fellow Scot Robert William Thomson). Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience".[4] The development of this technology hinges on myriad engineering advances. In terms of materials, the vulcanization of natural rubber is credited to Charles Goodyear and Robert William Thomson. Synthetic rubbers were invented in the laboratories of Bayer in the 1920's.[5] Today, over 1 billion tires are produced annually in over 400 tire factories, see List of Tire Companies. Manufacturing Main article: Tire manufacturing Pneumatic tires are manufactured in around 450 tire factories in the world. Over 1 billion tires are manufactured annually, making the tire industry the major consumer of natural rubber. In 2015 1.72 billion tires are expected to be sold globally.[6] Tire production start with bulk raw materials such as rubber, carbon black, and chemicals and produce numerous specialized components that are assembled and cured. Many kinds of rubber are used, the most common being styrene-butadiene copolymer. This article describes the components assembled to make a tire, the various materials used, the manufacturing processes and machinery, and the overall business model. Styrene-butadiene copolymer is the most popular material used in the production of rubber tires.[5] In 2004, $80 billion of tires were sold worldwide,[7] in 2010 it was $140 billion.[8] The top five tire manufacturing companies by revenue are Bridgestone, Michelin, Goodyear, Continental, and Pirelli.[9] Components A tire carcass is composed of several parts. Tread Main article: Tread 2 bicycle tires with different tread patterns The tread is the part of the tire that comes in contact with the road surface. The portion that is in contact with the road at a given instant in time is the contact patch. The tread is a thick rubber, or rubber/composite compound formulated to provide an appropriate level of traction that does not wear away too quickly. The tread pattern is characterized by the geometrical shape of the grooves, lugs, voids and sipes. Grooves run circumferentially around the tire, and are needed to channel away water. Lugs are that portion of the tread design that contacts the road surface. Voids are spaces between lugs that allow the lugs to flex and evacuate water. Tread patterns feature non-symmetrical (or non-uniform) lug sizes circumferentially to minimize noise levels at discrete frequencies. Sipes are valleys cut across the tire, usually perpendicular to the grooves, which allow the water from the grooves to escape to the sides in an effort to prevent hydroplaning. Treads are often designed to meet specific product marketing positions. High performance tires have small void ratios to provide more rubber in contact with the road for higher traction, but may be compounded with softer rubber that provides better traction, but wears quickly. Mud and snow (M&S) tires are designed with higher void ratios to channel away rain and mud, while providing better gripping performance. Specialized tires will always work better than general/all purpose/all weather tires when being used in the conditions the specialized tires are designed for. Tread lug Tread lugs provide the contact surface necessary to provide traction. As the tread lug enters the road contact area, or footprint, it is compressed. As it rotates through the footprint it is deformed circumferentially. As it exits the footprint, it recovers to its original shape. During the deformation and recovery cycle the tire exerts variable forces into the vehicle.[citation needed] These forces are described as Force Variation.[citation needed] Tread void Tread voids provide space for the lug to flex and deform as it enters and exits the footprint. Voids also provide channels for rainwater, mud, and snow to be channeled away from the footprint. The void ratio is the void area of the tire divided by the entire tread area. Low void areas have high contact area and therefore higher traction on clean, dry pavement. Rain groove The rain groove is a design element of the tread pattern specifically arranged to channel water away from the footprint. Rain grooves are circumferential in most truck tires. Many high performance passenger tires feature rain grooves that are angled from the center toward the sides of the tire.[citation needed] Some tire manufacturers claim that their tread pattern is designed to actively pump water out from under the tire by the action of the tread flexing.[citation needed] This results in a smoother ride in different types of weather.[citation needed] however diminishing and extending braking distances on wet and dry pavement by a few feet on siped tires. When the tread lugs are worn to the point that the wear bars connect across the lugs. also supports the load of the vehicle. This reduces shear stress in the lug and reduces heat build up. The width of the rim in relationship to the tire is a factor in the handling characteristics of an automobile. because the rim supports the tire's profile. The bead is typically reinforced with steel wire and compounded of high strength. the tires are fully worn and should be taken out of service. The sidewall is largely rubber but reinforced with fabric or steel cords that provide for strength and flexibility. that improve the flexibility of the lug to deform as it traverses the footprint area. .063 in) and are deemed "worn out" at that point. in conjunction with the air inflation. as many manufacturers now offer already siped off-road-tires. Sidewall Uneven sidewall wear.Sipe Tread lugs often feature small narrow voids. due to significant under-inflation The sidewall is that part of the tire that bridges between the tread and bead. Most wear bars indicate a remaining tread depth of 1. Off-road tire enthusiasts have been siping tires for years for greater traction. Sidewalls are molded with manufacturer-specific detail. Wear bar Wear bars (or wear indicators) are raised features located at the bottom of the tread grooves that indicate the tire has reached its wear limit. and sometimes decorative ornamentation. government mandated warning labels. down to fabric plies. The sidewall transmits the torque applied by the drive axle to the tread to create traction. Testing of identical siped and unsiped tires showed measurable improvements in snow traction and ice braking performance. The bead seats tightly against the two rims on the wheel to ensure that a tubeless tire holds air without leakage. like whitewalls. and other consumer information.[10] Bead The bead is that part of the tire that contacts the rim on the wheel. low flexibility rubber. The bead fit is tight to ensure the tire does not shift circumferentially as the wheel rotates.6 millimetres (0. or sipes. The sidewall. to prevent air leakage. many motorcycle tires. and many tires for large vehicles such as buses. Wheel Main article: Wheel Tires are mounted onto wheels that have most often have integral rims on their outer edges to hold the tire. and tractors are designed for use with inner tubes. The inner tubes are inserted into the tire and inflated to retain air pressure. heavy trucks.[12] These outer edges are shaped to obtain a proper shape on each side. Inner tubes are torus-shaped balloons made from an impermeable material.Shoulder The shoulder is that part of the tire at the edge of the tread as it makes transition to the sidewall. A decorative hubcap and trim ring may be placed over the wheel. or the "outer edge" of a wheel. sledding. Large inner tubes. Rim Main article: Rim (wheel) The beads of the tire are held on the rim. having a radially cylindrical inclined inner wall on which the tire can be mounted.[14] Inner tube Most bicycle tires. Automotive wheels are typically made from pressed and welded steel. tubing (recreation). such as soft. or a composite of lightweight metal alloys. which are large inflatable toruses. Purpose-built .[13] Tires are mounted on the wheel by forcing its beads into the channel formed by the wheel's inner and outer rims. The orientations of the plies plays a large role in the performance of the tire and is one of the main ways that tires are categorized. elastic synthetic rubber. such as swimming and rafting (see swim ring). These alloy wheels may be either cast or forged. and skitching. Associated components Several additional components may be required in addition to just the tire to form a functional wheel. such as aluminum or magnesium. The mounted tire and wheel assembly is then bolted to the vehicle's hub. Ply Plies are layers of relatively inextensible cords embedded in the rubber[11] to hold its shape by preventing the rubber from stretching in response to the internal pressure. can be re-used for other purposes. The wheel's rim must be of the proper design and type to hold the bead of the appropriately sized tire. or a Presta valve on high-performance bicycles. with successive plies laid at opposing angles forming a crisscross pattern to which the tread is applied. Construction types A cross-section of a tire showing ply orientations Bias Bias tire (or cross ply) construction utilizes body ply cords that extend diagonally from bead to bead. and eliminating the protruding valve stem. and other accessories. typically a Schrader valve on automobiles and most bicycle tires. handles. offering choice of colors. with a check valve. The rubber in valve stems eventually degrades.inflatable toruses are also manufactured for these uses. and. usually at angles in the range of 30 to 40 degrees. in the case of tubeless tires. fabric covering. in the case of tubeless tires. through which the tire is inflated. replacement of the valve stem at regular intervals or with tire replacement reduces the chance of failure. or are an integral part of the inner tube. The design allows the entire tire . Valve stems usually protrude through the wheel for easy access. decks. Schrader valve stem with its cap removed Valve stem Main article: Valve stem The valve stem is a tube made of metal or rubber. They mount directly to the rim. The belts may be cord or steel. puncture proof. Besides the impossibility of going flat. decreased "self-cleaning" ability and lower grip ability at low speeds. skateboards. The plies and belts are at different angles. Semi-pneumatic Semi-pneumatic tires have a hollow center. The advantages of this construction include longer tread life. and parallel to each other. providing the main advantage of this construction. They can also be rugged. but the interior has special compressible polyurethane springs to contribute to a comfortable ride. and provide cushioning. carts. and wheelbarrows. Belted bias A belted bias tire starts with two or more bias-plies to which stabilizer belts are bonded directly beneath the tread. Solid tires include those used for lawn mowers. Tires that are hollow but are not pressurized have also been designed for automotive use. golf carts. better steering control. and trailers. which is an experimental tire design being developed at Michelin. which improves performance compared to non-belted bias tires. the tires are intended to combine the comfort offered by higher- . but they are not pressurized. typically used in industrial applications. as well as stabilizer belts directly beneath the tread. wheelchairs. The belts may be cord or steel. and many types of light industrial vehicles. such as the Tweel (a portmanteau of tire and wheel). They are light-weight.body to flex easily. They are used on lawn mowers. a smooth ride on rough surfaces. scooters. and lower rolling resistance.[17] and are designed to not pull off their rim under use. Such tires are installed by means of a hydraulic tire press. One of the most common applications for solid tires is for material handling equipment (forklifts). This cushioning characteristic also causes the major disadvantages of a bias tire: increased rolling resistance and less control and traction at higher speeds. and are manufactured from solid rubber and plastic compounds via molding operations. while lessening rolling resistance because the belts increase tread stiffness. The outer casing is rubber as in ordinary radial tires. This construction provides smoother ride that is similar to the bias tire. low-cost.[16] These tires often come as a complete assembly with the wheel and even integral ball bearings. Disadvantages of the radial tire include a harder ride at low speeds on rough roads and in the context of off-roading.[15] Solid Many tires used in industrial and commercial applications are non-pneumatic. Radial Main article: Radial tire Radial tire construction utilizes body ply cords extending from the beads and across the tread so that the cords are laid at approximately right angles to the centerline of the tread. the vehicle may drive into a pot-hole.profile tires (with tall sidewalls) with the resistance to cornering forces offered by low profile tires. resulting in a tire laceration and blow-out. this often leads to side wall blow-outs. it heats up the tire wall to possibly dangerous temperatures. Some actually measure the air pressure. Most tires are stamped with a maximum pressure rating. The reason for this is that it increases the amount of tire wall movement as a result of cornering forces. as well as a damaged wheel. and diminishes tire contact area on the negative side of the vector. as well as degrades the steel wire reinforcement.[18] High performance and dynamic drivers often increase the tire pressure to near the maximum pressure as printed on the sidewall. Tires should not generally be inflated to the pressure on the sidewall. and the tire may deform to such an extent that the side wall on the positive vector side becomes in contact with the road. This is done to sacrifice comfort for performance and safety. rather than being damaged itself. with low tire pressure—due to the side wall being more pliable—the tire will absorb more of the irregular forces from normal driving. this is the maximum pressure. It is definitely very dangerous to allow tire pressure to drop below the recommended placard vehicle pressure. Further. the tire wall will be more pliable than had it been of a higher pressure. High tire pressures are more inclined to keep its shape during any encounter. and alert the driver when the pressure goes below a warning limit. and with this constant bending of the side wall as it absorbs the contours of the road. and "feel" the driver perceives of the . such as gauging when the relative size of the tire changes due to lower air pressure. This increases the entire roll movement of the car. thereby wedging the tire between the wheel and road. There are several types of designs to monitor tire pressure. Should a low pressure tire be forced to perform an evasive maneuver. The probability of failing in the emergency maneuver is thus increased. This allows for an increased reaction speed. and thus it will "roll" under the wheel. although this is commonly done temporarily when driving on sand to reduce chance of bogging. Inflation pressure Tires are specified by the vehicle manufacturer with a recommended inflation pressure. or a hard elevation in the road. the tires should be inflated to what the vehicle manufacturer recommends. rather than the recommended pressure. the side wall at the contact area will temporarily collapse. In an extreme case of this phenomenon. and some make indirect measurements. For passenger vehicles and light trucks. Thus only half the tire is in contact with the road. and will thus transmit the forces of the road to the suspension. Due to the low tire pressure. which is usually located on a decal just inside the driver's door or in the vehicle owners handbook. which permits safe operation within the specified load rating and vehicle loading. They have not yet been delivered for broad market use. Specifications Tire pressure monitoring system Main article: Tire pressure monitoring system Tire pressure monitoring systems (TPMS) are electronic systems that monitor the tire pressures on individual wheels on a vehicle. see tire code. in an attempt to keep the tires at the proper inflation pressure longer. Most modern tires will wear evenly at very high tire pressures. the tire contact patch is changed more than if it were over-inflated. It may be. and it is for this reason that vehicle owners should keep a personal pressure gauge with them to validate the correct tire pressure. Many pressure gauges available at fuel stations have been de-calibrated by manhandling and the effect of time. leading to aberrant and shearing forces on the feathering area. Some drivers inflate tires with nitrogen. Modern tire designs allow for minimal tire contact surface deformity during high pressures.[20] Tires are not completely impermeable to air. and with current basic tires. Feathering occurs on the junction between the tire tread and side wall. This is as a result of the inability of the tire to perform appropriately during cornering forces. but will degrade prematurely due to low (or even standard) pressures. that an increased tire pressure almost exclusively results in shorter stopping distances.road. This increases rolling resistance. instead of simple air. and friction between the road and tire. During the early stages of tire engineering. which is already 78% nitrogen. Over-inflation may increase the wear on the center contact patch. and tread separation in severe cases. An increased tire pressure has many benefits. It has been found. the tire contact patch is readily reduced by both over-and-under inflation.[22][23][24] Load rating Tires are specified by the manufacturer with a maximum load rating. and as a result the traditional wear on the center of the tire due to reasonably high pressures is only known to very old or poorly designed tires.[19] If tire pressure is too low. and minimize side wall blow outs. This is due to the tire moving sideways underneath the wheel as the tire pressures are insufficient to transmit the forces to the wheel and suspension. Loads exceeding the rating can result in unsafe conditions that can lead to steering instability and even rupture. with perfect wear until the end. This may be of negative economic value to the rubber and tire companies. Under-inflation can lead to tire overheating. tire flexing. and under-inflation will cause a concave tread. premature tread wear. Speed rating .[21] though the effectiveness of this is debatable. except in some circumstances that may be attributed to the low sample size. and so lose pressure over time naturally. that very high tire pressures have only two downsides: The sacrifice in comfort. Many individuals have maintained their tire pressures at the maximum side wall printed value (inflated when cold) for the entire lifetime of the tire. as a result of too low tire pressures. including decreased rolling resistance. resulting in less center contact. and the increased chance of obtaining a puncture when driving over sharp objects. as high tire pressures decrease wear. For a table of load ratings. such as on a newly scraped gravel road. indicated on the side wall with an arrow-like symbol . caster and toe angles. Brand A's rating of 500 is not necessarily going to give you the same mileage rating as Brand B's tire of the same rating. Tires designed to run 500 miles (800 km) or more per day carrying heavy loads require special specifications. Tread wear. also known as tire wear. The "test tires" are all manufacturer-dependent. For passenger vehicles these ratings range from 99 to 186 miles per hour (159 to 299 km/h). Rotation Tires may exhibit irregular wear patterns once installed on a vehicle and partially worn. such as frontto-rear. Government legal standards prescribe the minimum allowable tread depth for safe operation. Wheel alignment is the procedure for checking and correcting this condition through adjustment of camber. then the irregular wear will become substantial if left uncorrected. Treadwear rating Main article: Treadwear rating The treadwear rating or treadwear grade describes how long the tire manufacturers expect the tire to last.) are often given service ratings. The testing is non-regulated and can vary greatly. If the discrepancy in alignment is large. Wheel alignment Main article: Wheel alignment When mounted on the vehicle. front-wheel drive vehicles tend to wear the front tires at a greater rate compared to the rears. and some for stop-start multi-drop type work. and therefore may exhibit irregular wear. These settings also affect the handling characteristics of the vehicle. . Tire rotation is the procedure of moving tires to different car positions. is caused by friction between the tire and the road surface. Some ratings are for long haul. However care must be taken with unidirectional tires (tires that are designed to rotate in one direction only. Service rating Tires (especially in the U.The speed rating denotes the maximum speed at which a tire is designed to be operated. thereby extending the life of the tire. in order to even out the wear.S. A Course Monitoring Tire (the standard tire that a test tire will be compared to) has a rating of "100".is maintained after the swap. mainly used on bus and truck tires. If a manufacturer assigns a treadwear rating of 200 to a new tire. Furthermore. see tire code. for a vehicle that is going forward) so that the correct rotational direction . Treadwear ratings are only useful for comparing Brand A's entire lineup against itself. the wheel and tire may not be perfectly aligned to the direction of travel. they are indicating that they expect the new tire to have a useful lifespan that is 200% of the life of a Course Monitoring Tire. For a table of speed ratings. or any run-flat or skidded tires. including truckers. the mold or hot cure method and the pre-cure or cold one. but favorable compared to high-end brands.Retread Main article: Retread Tires that are fully worn can be re-manufactured to replace the worn tread. corroded belts or sidewall damage.[27] Many commercial trucking companies put retreads only on trailers. the pre-cure method involves the application of a ready-made tread band on the buffed and prepared casing. This is known as retreading or recapping. imbalance. but many drivers. In most situations. Casings with problems such as capped tread.[26] The percentage of retread failures should be about the same as for new tire failures. then that tire (new or recapped) will fail. Tires are checked at the point of manufacture for excessive static imbalance and dynamic imbalance using automatic tire balance machines. will be rejected. underinflated. Many of the details are modeled in Pacejka's Magic Formula. Balance Main article: Tire balance When a wheel and tire rotate. During the retreading process. taking the tread shape of the matrix. they exert a centrifugal force on the axle that depends on the location of their center of mass and the orientation of their moment of inertia. During the curing period. Tires are . unrepairable cuts. a process of buffing away the worn tread and applying a new tread. Some are explained below.[25] Retreading is economical for truck tires because the cost of replacing the tread is less than the price of a new tire. and. which later is cured in an autoclave so that vulcanization can occur. retread technicians must ensure the casing is in the best condition possible to minimize the possibility of a casing failure. tread separation. or mismatched to the other tire on a set of duals). Retreading passenger tires is less economical because the cost of retreading is high compared to the price of new cheap tires. On the other hand. Worn tires can be retreaded by two methods. using only new tires on their steering and drive wheels. if a tire is abused (overloaded. which is later cured in matrices. retread tires can be driven under the same conditions and at the same speeds as new tires with no loss in safety or comfort. or unbalance. This is referred to as balance. This procedure increases the driver's chance of maintaining control in case of problems with a retreaded tire. are guilty of not maintaining proper air pressure on a regular basis. vulcanization takes place and the raw rubber bonds to the casing. Performance characteristics The interaction of a tire with the pavement is a very complex phenomenon. The mold cure method involves the application of raw rubber on the previously buffed and prepared casing. parallel to the road surface) force produced by a vehicle tire during cornering. Centrifugal growth A tire rotating at higher speeds tends to develop a larger diameter. or friction ellipse is a useful way to think about the dynamic interaction between a vehicle's tire and the road surface. traction circle.[citation needed] Circle of forces Main article: Circle of forces The circle of forces. To facilitate proper balancing. There are two methods of match-mounting high performance tire to wheel assemblies using these red (uniformity) or yellow (weight) marks.[28] Camber thrust Main article: Camber thrust Camber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its Camber angle and finite contact patch. As the tire diameter grows. most high performance tire manufacturers place red and yellow marks on the sidewalls to enable the best possible match-mounting of the tire/wheel assembly. friction circle. Motorcycle tires are often designed with reinforcements aimed at minimizing centrifugal growth. or footprint.checked again in the auto assembly plant or tire retail shop after mounting the tire to the wheel. Assemblies that exhibit excessive imbalance are corrected by applying balance weights to the wheels to counteract the tire/wheel imbalance.e. The length-to-width ratio of the contact patch affects steering and cornering behavior. . the tire width decreases. due to centrifugal forces that force the tread rubber away from the axis of rotation. This centrifugal growth can cause rubbing of the tire against the vehicle at high speeds. is the area of the tread that is in contact with the road surface. of the tire. Contact patch Main article: contact patch The contact patch. This may cause speedometer error. Cornering force Main article: Cornering force Cornering force or side force is the lateral (i. This area transmits forces between the tire and the road via friction. which is equipped with a load roller similar to the force variation machine used at the factory to grade tire uniformity. These variations are collectively referred to as tire uniformity. or grip. Since the rubber is elastomeric. In the late 1990s. it is deformed during this cycle. under dry conditions. are measured using a tire uniformity machine at the tire factory at the end of the manufacturing process as a quality check. This machine can find the best position for the tire on a given wheel so that the over-all assembly is as round as possible. Tires outside the specified limits for RFV and LFV are rejected.Dry traction Dry traction is measure of the tire's ability to deliver traction. lateral force variation (LFV) and tangential force variation. it is the distance that the resultant force of side-slip occurs behind the geometric center of the contact patch. More technically. Radial and lateral force variation is measured on a force variation machine at the end of the manufacturing process. Force variation The tire tread and sidewall elements undergo deformation and recovery as they enter and exit the footprint. it imparts cyclical forces into the vehicle. Load sensitivity Main article: Tire load sensitivity Load sensitivity is the behaviour of tires under load. and sidewall bulge. Rolling resistance . including radial runout. Pneumatic trail Main article: Pneumatic trail Pneumatic trail of a tire is the trail-like effect generated by compliant tires rolling on a hard surface and subject to side loads. increases. Tire uniformity is characterized by radial force variation (RFV). Relaxation length Main article: Relaxation length Relaxation length is the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value. the load sensitivity of most real tires in their typical operating range is such that the coefficient of friction decreases as the vertical load. Geometric parameters. As the rubber deforms and recovers. as in a turn. Fz. lateral runout. Conventional pneumatic tires do not behave as classical friction theory would suggest. Namely. Hunter Engineering introduced the GSP9700 Road Force balancer. Dry traction is a function of the tackiness of the rubber compound. As the tire rolls. which may lead to its premature failure. where rolling resistance accounts for a high proportion of fuel consumption. Tire makers seek lower rolling resistance tire constructions to improve fuel economy in cars and especially trucks. The measurement's appellation and units are the same. and so usually have a slightly shorter stopping distance.e. For this reason. Pneumatic tires also have a much lower rolling resistance than solid tires. The energy required to make the deformation depends on the inflation pressure. such as spring force and stiffness. Slip angle Main article: Slip angle Slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing (i. The recent shortage and increasing cost of tires for heavy equipment has made TKPH an important parameter in tire selection and equipment maintenance for the mining industry.Main article: Rolling resistance Rolling resistance is the resistance to rolling caused by deformation of the tire in contact with the road surface. Stopping distance Performance-oriented tires have a tread pattern and rubber compounds designed to grip the road surface.. The difference between the rolling resistance of a pneumatic and solid tire is easily felt when propelling wheelchairs or baby buggies fitted with either type so long as the terrain has a significant roughness in relation to the wheel diameter. Work load The work load of a tire is monitored so that it is not put under undue stress. as is the case with a solid (or foam-filled) tire. the angle of the vector sum of wheel translational velocity and sideslip velocity ).e. i. a pneumatic tire is able to "absorb" bumps in the road as it rolls over them without experiencing a reaction force opposite to the direction of travel. and numerous physical properties of the tire structure. specific braking tests are necessary for data beyond generalizations. .[29] Work load is measured in ton kilometre per hour (TKPH). rotate it around its vertical axis.[citation needed] Self aligning torque Main article: Self aligning torque Self aligning torque. Because the internal air pressure acts in all directions. also known as the aligning torque. rotating speed. manufacturers of tires for large earth-moving and mining vehicles assign TKPH ratings to their tires based on their size. is the torque that a tire creates as it rolls along that tends to steer it. tread enters the contact area and is deformed flat to conform to the roadway. SAT or Mz. However. the code was switched to a 4-digit code. when properly inflated have a sufficiently small footprint to not be susceptible to hydroplaning. The last four numbers represent the week and year the tire was built. so for example. Gravel roads. and other rough terrain causes accelerated wear. a tire manufactured in the 17th week of 1998 would have the code 178Δ. In 2000. the DOT Code is an alphanumeric character sequence molded into the sidewall of the tire for purposes of tire identification. Thus. See also Work load above. In this case it means 1988. and heel-toe wear. For such tires. 178 means it was manufactured in the 17th week of 8th year of the decade. Same rules apply. under wet conditions. However. 3003 means the tire was manufactured in the 30th week of 2003. the placard pressure is too low and most tires are underinflated as a result. as the rotation may not be perfectly circular. Tire manufacturers and car companies have mutually established standards for tread wear testing that include measurement parameters for tread loss profile.[32] Markings DOT code In the United States.[citation needed] Unbalanced wheels can cause uneven tire wear. but there is a little triangle (Δ) after the DOT code. The DOT Code begins with the letters "DOT" followed by a plant code (two numbers or letters) that identifies where it was manufactured. tread type. Under-inflation causes excessive wear to the outer ribs. or grip. the same code holds true. tires with a circular cross-section.[30][31] The rating is based on the weight and speed that the tire can handle without overheating and causing it to deteriorate prematurely. it is observed that fully slick tires will give superior traction on both wet and dry pavement. A three-digit code was used for tires manufactured before 2000. The equivalent measure used in the United States is ton mile per hour (TMPH). For example.S. lug count. E-mark .construction. rocky terrain. The DOT Code is useful in identifying tires in a product recall. The DOT Code is mandated by the U. Over-inflation above the sidewall maximum can cause excessive wear to the center of the tread. Wet traction Wet traction is the tire's traction. and rubber compound. Often. Wet traction is improved by the tread design's ability to channel water out of the tire footprint and reduce hydroplaning. For tires manufactured in the 1990s. Tread wear There are several types of abnormal tread wear. Poor wheel alignment can cause excessive wear of the innermost or outermost ribs. Department of Transportation. Modern tires have steel belts built in to prevent this. Other numbers are marketing codes used at the manufacturer's discretion. such as those found on racing bicycles. A (lower case) "e" indicates that the tire is certified to comply with the dimensional. In most markets. and even among tire models of the same manufacturer. The mark itself is either an upper case "E" or lower case "e" – followed by a number in a circle or rectangle. factories that manufacture passenger and light truck radial tires are separate and distinct from those that make aircraft or off-the-road (OTR) tires. Since the manufacturing process. The number in the circle or rectangle denotes the country code of the government that granted the type approval. so that the tire. Mold serial number Tire manufacturers usually embed a mold serial number into the sidewall area of the mold. They feature a softer rubber compound for improved traction. performance and marking requirements of Directive 92/23/EEC. it is common for tire factories to specialize in one or more tire types. a more "sporty" driving style. based on the type of vehicle they serve. especially on high speed cornering. once molded. Codes Main article: Tire code Vehicle applications Tires are classified into several standard types. followed by a further number. and equipment vary according to the tire type. This is an area of active research and development. performance and marking requirements of ECE regulation 30. as well as marketing.[citation needed] The ability to provide a high level of performance on both wet and dry pavement varies widely among manufacturers. The last number outside the circle or rectangle is the number of the type approval certificate issued for that particular tire size and type. can be traced back to the mold of original manufacturer. Mud and snow Main article: Snow tires .[citation needed] Passenger vehicles and light truck High performance High performance tires are designed for use at higher speeds. raw materials.All tires sold for road use in Europe after July 1997 must carry an E-mark. The trade off of this softer rubber is shorter tread life. An (upper case) "E" indicates that the tire is certified to comply with the dimensional. High performance street tires sometimes sacrifice wet weather handling by having shallower water channels to provide more actual rubber tread surface area for dry weather performance. and more often. or M&S). There are no traction performance requirements which such a tire has to meet. Dedicated winter tires will bear the "Mountain/Snowflake Pictograph" if designated as a winter/snow tire by the American Society for Testing & Materials. below).g. M&S relates to the percentage of tread void area. compared to summer tires. Studded. The studs also roughen the ice. The tread compound is usually softer than that used in tires for summer conditions. but wears more quickly at higher temperatures. Other winter tires rely on factors other than studding for traction on ice.The examples and perspective in this section may not represent a worldwide view of the subject. Some jurisdictions may require snow tires or tire chains on vehicles driven in certain areas during extreme weather conditions. Please improve this article and discuss the issue on the talk page. Use of studs is restricted in most countries with the notable exception of the Nordic countries where they are commonly used during the winter season outside metropolitan areas. Winter tires will typically also carry the designation MS. winter tire Some winter tires may be designed to accept the installation of metal studs for additional traction on icy roads. or the words MUD AND SNOW (but see All-season tires. studs are never used on heavier vehicles. highly siped. Typically. . thus providing better grip on ice and snow. except ice resurfacers. The upper tier classes of ice racing[33] and rallying mandates the vehicles be equipped with studded tires. and even prohibited in some locales due to the increased road wear caused by studs. e. thus providing better friction between the ice and the soft rubber in winter tires. is a designation applied rather arbitrarily by manufacturers for all-season and winter tires designed to provide improved performance under low temperature conditions. highly porous or hydrophilic rubber that adheres to the wet film on the ice surface. M&S. (or M+S. Tires may have well above average numbers of sipes in the tread pattern to grip the ice. (July 2010) Mud and Snow. become ubiquitous as original and replacement equipment on automobiles marketed in the United States. open design also allows mud to clear quickly from between the lugs. thus allowing the tires to penetrate the snow layer and grip harder snow or road surface beneath. Spare Main article: spare tire Some vehicles carry a spare tire.Mud tires are speciality tires with large. Being thinner. However in reasonable amounts of mud and snow. Even so. chunky tread patterns designed to bite into muddy surfaces. in other parts of the world. tires should be thinner. or "space-saver spare" tires are smaller than normal tires to save on trunk/boot space. give good performance on snow and ice. weight. gas mileage. All season The All Season tire classification is a compromise between one developed for use on dry and wet roads during summer and one developed for use under winter conditions. Minispares have a short life expectancy and a low speed rating. The type of rubber and the tread pattern best suited for use under summer conditions cannot. like Germany. to be used in the event of flat tire or blowout. Run-flat Main article: Run-flat tire . already mounted on a wheel. it is common to have a designated tire set for winter and summer. where the vehicle will sink into the snow and plough the snow in front and eventually pack it beneath it until the wheels no longer have traction. often below 60 miles per hour (97 km/h). Many tires in the all-terrain category are designed primarily for on-road use. winter performance is usually poorer than a winter tire. Mud terrain tires also tend to be wider than other tires. All-terrain All-terrain tires are typically used on SUVs and light trucks. the tread pattern offers wider spacing than all-season tires to remove mud from the tread. as they have a larger contact patch and are better able to 'float' on top of the mud or snow. for technical reasons. Minispare. the tire will have more pressure on the road surface. This does not compensate when the snow is too deep for such penetration. The all-season tire is a compromise. Owing to the compromise with performance during summer. AllSeason tires are also marked for mud and snow the same as winter tires but rarely with a snowflake. due to their convenience and their adequate performance in most situations. They have. wider tires are preferred. particularly all-terrain tires that are originally sold with the vehicle. In this case. The large. These tires often have stiffer sidewalls for greater resistance against puncture when traveling off-road. however. to spread the weight of the vehicle over a greater area to prevent the vehicle from sinking too deeply into the mud. and is neither an excellent summer tire nor an excellent winter tire. and cost. Off-the-road . material compounds. dump trucks. The Super Single replaces these with a single tire. usually 455 mm wide. load-supporting sidewalls. These tires typically feature strong. each between 275 mm295 mm wide. This allows for less tread to be contacting the ground and also eliminates 2 sidewalls per position. An infamous example of an alternate run-flat technology has plastic load-bearing inserts attached to the rim instead of the reinforced sidewalls. and passenger buses.Several innovative designs have been introduced that permit tires to run safely with no air for a limited range at a limited speed. A relatively new concept is the use of "Super Singles" or Wide Singles. A disadvantage is that run-flat tires cannot be repaired if a puncture occurs. and trailer. Truck tires are subcategorized into specialties according to vehicle position such as steering. Heavy duty truck Heavy load may require multiple tires Heavy duty tires are also referred to as Truck/Bus tires. These are the tire sizes used on vehicles such as commercial freight trucks. this is due to manufacturer's informing the automotive industry that you cannot tell what kind of state the sidewall is in due to the compacted sidewall of rubber. and tread patterns that best optimize the tire performance. Each type is designed with the reinforcements. this enables vehicles using these to improve fuel economy. there are 2 tires per position. Along with the weight savings of about 91 kilograms (200 lb) per axle. Generally in a dual configuration. drive axle. the technician must inspect the tire. repairing defects. multi-million dollar trucks can be idled for lack of tires. High flotation tires are used in swampy environments and where soil compaction is a concern. Racing . a new OTR tire can cost up to $50. "skiving" follows this. trenchers. widely spaced lugs to allow the tire to grip soil easily. Lastly. OTR tires can be of either bias or radial construction although the industry is trending toward increasing use of radial. Driven wheels have very deep. applies a cement gum adhesive. by hand. of material the buffing misses. Next. featuring large footprints at low inflation pressures. as well as large mining trucks. This has led to a stronger effort to recycle old OTR tires. Dramatically increasing commodity prices has led to shortages of new tires.000. As a consequence. backhoes. the technician fills holes in the tire with rubber. and places the tire on a machine that will apply a new tread. typically tractors and specialty vehicles like harvesters. First. and the like.[34] Retreading an OTR tire is labor intensive. which is the removal. retread tires are sold at half the price of new tires. graders.Off-the-road (OTR) tires being transported Off-the-road (OTR) tires include tires for construction vehicles such as wheel loaders. Bias OTR tires are built with a large number of reinforcing plies to withstand severe service conditions and high loads.[35] Agricultural The agricultural tire classification includes tires used on farm vehicles. As of 2008. costing mines millions of dollars in lost productivity. the retreading technician must place the old tire in a buffing machine to remove what remains of the old tread. and last 80% as long. Tires are specially engineered for specific race tracks according to surface conditions. and track temperature. rallying. MotoGP and the like. IndyCar. Racing tires often are not legal for normal highway use. Racing tires often are engineered to minimum weight targets. NASCAR. drifting. Time Attack. cornering loads. Road Racing – as well as the large-market race tires for Formula One. Bicycle Main article: Bicycle tire . so tires for a 500 miles (800 km) race may run only 100 miles (160 km) before a tire change. Auto-x. Some tire makers invest heavily in race tire development as part of the company's marketing strategy and a means of advertising to attract customers.NASCAR tires Racing tires are highly specialized according to vehicle and race track conditions. Industrial Airless tire The Industrial tire classification is a bit of a catch-all category and includes pneumatic and nonpneumatic tires for specialty industrial and construction equipment such as skid loaders and fork lift trucks. This classification includes tires for drag racing. Aircraft Changing a tire on a P-3C Orion aircraft Aircraft tires are designed to withstand extremely heavy loads for short durations. 1. Tests of airline aircraft tires have shown that they are able to sustain pressures of maximum 800 pounds per square inch (55 bar. and for braking effect. but common compressed air sources may contain moisture. up to 200 pounds per square inch (14 bar. Aircraft tire tread patterns are designed to facilitate stability in high crosswind conditions. mountain bike tires.[citation needed] Aircraft tires generally operate at high pressures. Aircraft tires are usually inflated with nitrogen or helium to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight. 5. instead of helium or nitrogen. which increases the expansion rate with temperature. used also with other human-powered vehicles (see Category:Human-powered vehicles). and tubular tires. snow tires.[citation needed] Dry nitrogen expands at the same rate as other dry atmospheric gases. to channel water away to prevent hydroplaning. and even higher for business jets.500 kPa) before bursting. . The number of tires required for aircraft increases with the weight of the plane (because the weight of the airplane has to be distributed better). During the test the tires have to be filled with water. which is the common content of aircraft tires.400 kPa) for airliners.A bicycle tire in the style of a cruiser This classification includes all forms of bicycle tires. to prevent the test room being blown apart by the energy when the tire bursts. including road racing tires. be used instead of air for inflation of tires on certain transport category airplanes was prompted by at least three cases in which the oxygen in air-filled tires combined with volatile gases given off by a severely overheated tire and exploded upon reaching autoignition temperature. Street and sport street tires have good traction even when cold. but when warmed too much. thus minimizing damage to aircraft and objects in the surrounding environment. Racing slicks are also made of a harder rubber compound and do not provide as much traction as street tires until warmed to a higher internal temperature than street tires normally operate at. there will be less contact patch in the center. They have more of a triangular form. Sound and vibration characteristics Main article: Roadway noise The design of treads and the interaction of specific tire types with the roadway surface type produces considerable effect upon sound levels or noise pollution emanating from moving vehicles. causing the tire to develop a flat spot quicker when used to ride on straightaways for long periods of time and have no tread so they lose almost all grip in wet conditions. These tires are not recommended for the street by manufacturers. such as nitrogen. Most street riding will not put a sufficient amount of friction on the tire to maintain the optimal tire temperature.[36] Motorcycle Main article: Motorcycle tyre There are many different types of motorcycle tires: This section's factual accuracy is disputed. Due to the triangulation of the tire. and are known to have a shorter life on the street. (April 2008) Sport Touring – these tires are generally not used for high cornering loads. The requirement that an inert gas. can actually lose traction as their internal temperature increases. especially in colder climates and in spring and fall. These sound intensities increase with higher vehicle speeds. These tires do not have a long life. The fuses provide a safer failure mode that prevents tire explosions by deflating in a controlled manner. Tires often overheat if maximum braking is applied during an aborted takeoff or an emergency landing. The use of an inert gas for tire inflation will eliminate the possibility of a tire explosion. Track or Slick – these tires are for track days or races. which in turn gives a larger contact patch while leaned over. but for long straights. good for riding across the country.Aircraft tires also include heat fuses.[37] The acoustic intensity . Sport Street – these tires are for aggressive street riders that spend most of their time carving corners on public roadways. but in turn have better traction in high speed cornering. designed to melt at a certain temperature. T&RA The Tire and Rim Association (T&RA) is a voluntary U. ETRTO The European Tyre and Rim Technical Organization (ETRTO) is the European standards organization "to establish engineering dimensions. and temperature. load/pressure characteristics and operating guidelines" . rims and valves. governmental body authorized by the U. is a system for comparing the performance of tires.S.[38] Regulatory bodies DOT The United States Department of Transportation (DOT) is the U.[39] for tires.S.produced varies considerably depending on the tire tread design and the road surface type.S.104. Of particular interest.S. standards organization to promote the interchangeability of tires and rim and allied parts. and load / inflation standards. key rim contour dimension standards. There is a study "under development" that aims predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle". UTQG The Uniform Tire Quality Grading System (UTQG). traction. Congress to establish and regulate transportation safety in the United States of America. TREAD Act . JATMA The Japanese Automobile Tire Manufacturers Association (JATMA) is the Japanese standards organization for tires. NHTSA The National Highway and Traffic Safety Administration (NHTSA) is a U. The UTQG regulation requires labeling of tires for tread wear. they published key tire dimension standards. established by the United States National Highway Traffic Safety Administration according to the Code of Federal Regulations 49 CFR 575. government body within the Department of Transportation tasked with regulating automotive safety in the United States. It is analogous to T&RA. key tire valve dimension standards. rims and valves. It is analogous to T&RA and ETRTO. including the manufacturer's name. Accountability and Documentation Act (TREAD Act) is a United States federal law that sets standards for testing and the reporting of information related to products involved with transportation such as cars and tires. With China's entrance into the WTO. manufacturing date. and in some cases test data. Before CCC. RFID transponders can remotely read this data automatically. After the termination of a one-year grace period in August 2003. RFID tags are used by auto assemblers to identify tires at the point of assembly to the vehicle. On the other hand. there were two certification systems in China: CCIB and CCEE. and may also be illegal. Safety Proper vehicle safety requires specific attention to inflation pressure. certain combinations of cross ply and radial tires on different wheels of the same vehicle can lead to vehicle instability. location of manufacture. CCC (China Compulsory Certification) is a mandatory certification system concerning product safety in China that went into effect in August 2002. Also. Over-inflated tires run the risk of explosive decompression (they may pop). tread depth. tire type. Vehicle and tire manufacturers provide owners' manuals with instructions on how to check and maintain tires. the system became compulsory. Excessive tire wear will reduce steering and braking response.[citation needed] Fleet operators utilize RFID as part of tire maintenance operations.[citation needed] Tags are encoded with various types of manufacturing data. these two systems were unified into the CCC certification system. Flat Main article: Flat tire . under-inflated tires have a higher rolling resistance and suffer from overheating and rapid tread wear particularly on the edges of the tread. RFID tags Radio Frequency IDentification tags (RFID) are passive transponders affixed to the inside of the tire for purposes of automatic identification. and general condition of the tires.The Transportation Recall Enhancement.The CCC certification system is operated by the State General Administration for Quality Supervision and Inspection and Quarantine of the People's Republic of China (AQSIQ) and the Certification and Accreditation Administration of the People's Republic of China (CNCA).[citation needed] and tires worn down past their safety margins and into the casing run the very real risk of rupturing. Tire designers have tried to make new tires fail-safe so that the failure of the operator to maintain the tire pressure won't cause a major safety concern. A tire that has lost sufficient pressure will impair the stability of the vehicle and may damage the tire further if it is driven in this condition. and put the occupants and other vehicles in danger. Hydroplaning (or aquaplaning) Main article: Hydroplaning (road vehicle) Hydroplaning. on a freeway) the tread could peel off. In tropical climates.A flat tire A flat tire occurs when a tire deflates. and more care should be taken in these climates to ensure that tires do not fail. usually at reduced speed. also known as aquaplaning. and once the vehicle is traveling at high speeds (i. it is of virtually no concern to bicycle tires under normal riding conditions largely because of the lower speeds.e.[citation needed] Also. Dangers of aged tires Research and tests show that as tires age. When hydroplaning occurs. they begin to dry out and become potentially dangerous. but rubber degrades over time. Some tires. (This is especially true of tires with a low aspect ratio. A modern radial tire may not be visibly distorted even with dangerously low inflation pressure. leading to severe loss of control. have either extremely stiff sidewalls or a resilient filler to allow driving a limited distance while flat. The tire should be changed and/or repaired before it becomes completely flat. a leak. such as Singapore. creating a very unsafe driving condition. tires degrade sooner than in temperate climates. requiring immediate attention. there is considerably less responsiveness of the steering wheel. but there are limitations on this. The correction of this unsafe condition is to gradually reduce speed. the tire effectively "floats" above the road surface on a cushion of water – and loses traction. When hydroplaning occurs. by merely lifting off the accelerator/gas pedal. This can occur as a result of normal wear-and-tear. tires on . is the condition where a layer of water builds up between the tire and road surface.) Thus maintenance of adequate tire pressure can have important safety implications despite the fact that most car owners neglect it. known as "run-flat tires". possibly damage the rim and vehicle. Hydroplaning occurs when the tread pattern cannot channel away enough water at an adequate rate to ensure a semi-dry footprint area. braking and steering. Hydroplaning becomes more prevalent with wider tires (because of the lower weight per contact area) and especially at higher speeds. even if unused. Aged tires may appear to have similar properties to newly manufactured tires. sometimes known as "low profile" tires. A flat tire or low-pressure tire should be considered an emergency situation. or more serious damage. Continuing to drive a vehicle with a flat tire will damage the tire beyond repair. without permanent damage or hazard. The chance of car hydroplaning is also minimal at bicycle speeds as the weight per contact area of car tires is not much lower if any than bicycle tires. developed over 30 years back but not yet universally used. since the tires often hold water inside and remain warm enough for mosquito breeding. releasing hydrocarbons and other contaminants to the . granulating the rubber and then a chemical process where it is mixed with other usual materials for macadamised roads.[43] Many states have regulations as to the number of scrap tires that you may have on site.seldom-used trailers are at the greatest risk of age-failure. an investigative report by Brian Ross on ABC's 20/20 news magazine found that many major retailers such as Goodyear. due to concerns with dumping. Wal-Mart. more resilent resulting in a smoother ride and also longer tire life. Guelph. but most do not. It also creates a fire danger. but some tires are built to withstand idleness.[40][41] Scrap tires and environmental issues A child plays in a playground made from recycled tires. Many automakers recommend replacing tires after six years. Currently. reusable crash cushions". since water does not adequately penetrate or cool the burning tires. and processing into new products. Tires have been known to liquefy. Canada Once tires are discarded. Some facilities are permitted to recycle scrap tires through chipping. Mosquitoes create a nuisance and may increase the likelihood of spreading disease. Several countries (for example. In the past. is to process scrap tires as raw material for roads. Some tires may also be retreaded for re-use. Scrap tires are often re-used for things from bumper car barriers to weights to hold down tarps. The resulting roads have proved to have better waterproofing. The process is removing the metal. and several tire manufacturers (Bridgestone. and Sears were selling tires that had been produced six or more years ago.[42] An interesting use. Michelin) have called for tires to be removed from service 10 years after the date of manufacture. South Korea) have regulations requiring its use. However. they are considered scrap tires. This creates a breeding ground for mosquitoes. since such a large tire pile is a lot of fuel. Americans generate about 285 million scrap tires per year. usually with nylon reinforcement. One group did "a study to evaluate the possibility of using scrap tires as a crash cushion system. no law for aged tires exists in the United States. or selling the material to licensed power plants for fuel. The objective of this study was to evaluate the material properties of used tires and recycled tire-derived materials for use in low-cost. and mosquitoes. millions of tires have been discarded into open fields. fire hazards. Some tire fires have burned for months. under extreme heat and temperatures from a fire. This usually takes the form of v-shaped grooves that help to disperse water from the center to the edge of the tread. The use of scrap tire chips for landscaping has become controversial. which will tend to be steered off course. See also  Camber thrust  Ground pressure  Tire-pressure gauge . braking performance. since tread contact changes according to the change in alignment during travel. and turning performance.[44] Of particular concern is evidence that some of the compounds that leach from tires into water. This type of tires is used in many cases to promote tire performance. contain hormone disruptors and cause liver lesions. Stabilizing belts An asymmetric tire may refer to a passenger car radial tire in which asymmetric structure stabilizing belts are built. Tires may also be directional. where the tread pattern favors operation in one direction. Symmetric directional tires can be used on both sides. Some directional tires are also asymmetric.[45] Asymmetric tire An asymmetric tire is a term used to describe some specific stabilization methods used in cars. which results in safer driving. They may be mounted on either side of the vehicle. However. Generally the stabilizing belts give a self-aligning torque when a motor vehicle is running straight ahead as well as when it is cornering. in which case there will be specific left and right-handed versions. The progressive change will harden the sidewalls to produce an immediate response to steering. This restricts tire rotation. The lateral force will be transmitted from the front wheel to the rear of the vehicle. Since the tread pattern of many ordinary tires do not form symmetry in relation to design or pattern noise.ground and even ground water. thus having a distinct inside and outside edge. Tire tread An asymmetric tire may refer to a tire whose tread pattern does not form in line symmetry or point symmetry vis-à-vis its central line. Whereas the asymmetric belts bring a gradual change in the lateral displacement of the tire tread corresponding to the rim while the cornering load grows. the sidewalls of the radial tire are so flexible that there will be a delay in the lateral reaction between the tread of the tire and the rim of its wheel as the vehicle is being steered positively. since the tread pattern will be in the wrong direction. Zinc is concentrated (up to 2% by weight) to levels high enough to be highly toxic to aquatic life and plants. but once mounted on a rim cannot be moved to the other side. The black smoke from a tire fire causes air pollution and is a hazard to down wind properties. due to the leaching of metals and other contaminants from the tire pieces. the method of mounting tires is specially prescribed. 3. ^ Dunlop. John Boyd (2008). 11. "How can I tell when my tyres need changing?". called plies. 5. Emulsion Rubbers" in Ullmann's Encyclopedia of Industrial Chemistry. A Dictionary of Modern English Usage: The Classic First Edition. Occupational Safety and Health Administration. ^ Jones. Retrieved 2012-03-14.) (2009). 14. Retrieved 2009-01-16. 2011. Retrieved 2011-03-16. and wheels". 13. ^ Global tire industry hits $80 billion. 2010-2011 Market Research Report . Christiane Oppenheimer-Stix. Elizabeth.com. David Crystal (ed.7 Billion Units by 2015. p. AccessScience. 2. 26. ISSN 0161-7370. 553. Thomas H. Jean-Pierre Lambert. Wiley-VCH. vol. Reza N.02 December 2010 10. (2006). The Pocket Oxford Dictionary and Thesaurus.1002/14356007. Retrieved 2010-10-23. ISBN 978-0-19953534-7. ^ "Bias vs Radial Tires". ^ KwikFit. p. 19. ^ "Demounting and Mounting Procedures". 15. ed. 2012. (1911). "Get things moving with casters. ^ "Thomas Net sources for industrial use 'Semi-Pneumatic Wheels'"." 12. . ^ Global Tire Shipments to Reach 1.o23_o01 6. 11. "Inner layers are made of different fabrics. ^ "Car Talk Service Advice: Tire Pressure". Encyclopædia Britannica. doi:10. Retrieved 2009-01-16. (2008). Volume 40. 17. 722. 20. Encyclopædia Britannica. According to a New Report by Global Industry Analysts. ISBN 978-0-521-62181-6. 655. ISBN 978-0-19-530715-3. p.com. Mud-throwers. 16. pp. Retrieved 9 July 2009. Hugh. Springer. Weinheim. W.. | Goliath Business News 8. ^ Peters. Cambridge University Press. ^ [1][dead link] 9. (1980). Retrieved 2010-10-23. John Dunn and Ralf Krüger "Rubber. ed. The Cambridge Guide to English Usage. 1914-04-02. ^ Research Report on World's Top 50 Tire Enterprises. ^ American Machinist. 1007. Michael Happ. Retrieved 2010-10-23. 597–598. 18. 4.     Central Tire Inflation System Cornering force Direct tire pressure monitoring system Dry steering Groove wander      Low-rolling resistance tires Pneumatic trail Relaxation length Skid mark Slip (vehicle dynamics)     Tire-pressure monitoring system Tire label Tire recycling Tramlining References 1. H. 4. Retrieved 2010-10-23. ^ "NHTSA test". ISBN 978-0-387-74243-4. ^ "FEA Chapter III: Tire pressure survey and test results". Hutchinson Dictionary of Scientific Biography. Pam (2004). Retrieved 2009-01-16. glides. Thomasnet. ^ Jewel. ^ a b Chisholm. Vehicle dynamics: theory and applications. ^ a b c d Fowler. Retrieved 2012-03-14. p. ^ a b Werner Obrecht. ^ Jazar. Retrieved 2012-03-14. Oxford University Press. Oxford University Press. Popular Science 216 (5): 148. Inc 7. p. "Bottom line: Overall. ^ Brown. ^ "ABC News: Aged Tires Sold as 'New' by Big Retailers". Consumer Reports. Abcnews. 43. "An Assessment of Environmental Toxicity and Potential Contamination from Artificial Turf using Shredded or Crumb Rubber" (PDF). 23. ^ Hogan. ^ Brodsky. ^ "Tire-Derived Fuel". ^ Lecomte. Archived from the original on November 6. ^ My Kingdom for a Tire. Retrieved 2008-07-01. ^ "Understanding Retreading". Tire Science & Technology 37. ^ Hossain. 2008. .21. Retrieved October 7. Scientific American. 40. "Aged Tires: A Driving Hazard?". Belgium: ETRTO. "Tires . 30. ^ My Kingdom for a Tire. Environmental Protection Agency.Nitrogen air loss study". Business Week. Retrieved 2011-12-10. ^ Petersen. Retrieved 2010-10-23. Retrieved 2008-0930.1007/BF00159677. ^ SAE. 2008. (2006). Retrieved 201010-23. International Tire & Rubber Association. "Dear Tom and Ray". 36. pp. Retrieved 2010-10-23. "TKPH application". Retrieved 2010-06-29. Journal of Materials in Civil Engineering. Retrieved 201010-23. Retrieved 2010-06-29. 48 36. p. 32." 25. consumers can use nitrogen and might enjoy the slight improvement in air retention provided. ISSN 0049-6979. Nabors. 2006. Daniel (Jan–Feb 2005). U. Air. U. 2007. Retrieved 2011-12-29. & Soil Pollution (Springer Verlag) 2 (3): 387–392. 2006. ^ Bridgestone. pp. 42. April 21. Archived from the original on September 27. ^ Tom and Ray Magliozzi (February 2005).[dead link] 28. Business Week. Retrieved October 7. Retrieved 1 July 2009.go. 33. Michael (September 1973). "Analysis of highway noise". Ross (2010-05-21). Retrieved October 7. 2008-09-24. ^ ETRTO Standards Manual 2007. "How to use TKPH". 2008. Gene (October 4.com. Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire. ^ Lydall.2.go. ^ 05/09/2008 (2008-05-09). Environmental Protection Agency. ^ Markus. "Federal Government Endorses the Use of Retreaded Tires". Retrieved 2010-10-23. September 30. 2007. I. 44. 38. Testing and evaluation of used automobile tires and recycled tire-derived materials for low-cost crash cushions. ^ "Do Nitrogen-Filled Tires Enhance Fuel-Efficiency?". CarTalk. 34. 46–48 35. ^ Federal Aviation Administration. ^ "Retread Tires". Bruxelles.S. ^ Yokohama 29. Sheldon. 2007.com. C. 22. Use of Nitrogen or Other Inert Gas for Tire Inflation in Lieu of Air 37. 41. but it's not a substitute for regular inflation checks. doi:10.S. "Racing Fast 'n' Cheap: Ice Racing". 27. Retrieved 2009-06-01. Motor Trend.com. ^ Goodyear. 2007.[dead link] 26. "New temperature prediction model improves on current TKPH formula". Retrieved 2010-06-29. ^ Sullivan. "Taking a ride on Boris's hot wheels hire bikes". Frank. April 21. "Sheldon Brown on tires". London Evening Standard. Journal of Water. C (2009). Joseph P. 24. Abcnews. 2007). Tire Retread Information Bureau. Mustaque. 39. 31. Harvey. Retrieved 2010-10-23. Look up tire or tyre in Wiktionary. the free dictionary. Wikimedia Commons has media related to: Tires   National Highway Traffic Safety Adm "Tire Safety" Brochure U.45. Government tire rating and maintenance site. Retrieved 200906-01. the free dictionary. [show]    v t e Automotive design [show]    v t e Automotive handling related articles View page ratings Rate this page What's this? Trustworthy Objective Complete Well-written I am highly knowledgeable about this topic (optional) Categories:    Scottish inventions Tires Tire manufacturers . External links Look up inner tube in Wiktionary. "The Myth of Rubberized Landscapes" (PDF). ^ Chalker-Scott. Linda.S.         Auto parts Create account Log in Article Talk Read Edit View history       Main page Contents Featured content Current events Random article Donate to Wikipedia Interaction      Toolbox Print/export Languages            Help About Wikipedia Community portal Recent changes Contact Wikipedia ‫ال عرب ية‬ Aragonés Беларуская Български Català Česky Dansk Deutsch Español Esperanto ‫ف ار سی‬ . . See Terms of use for details.                                       Français 한국어 हिन्दी Bahasa Indonesia Italiano ‫עברית‬ Basa Jawa Kurdî Latviešu Lingála Magyar മലയാളം Bahasa Melayu Nederlands 日本語 norsk ( okm l) norsk (nynorsk) Occitan Polski Português Română Runa Simi Русский Simple English Slovenčina Slovenščina Basa Sunda Suomi Svenska தமிழ் ไทย Türkçe Українська ‫اردو‬ Winaray 粵語 中文 This page was last modified on 5 August 2012 at 12:55. Contact us  . Inc. a non-profit organization. Text is available under the Creative Commons Attribution-ShareAlike License. additional terms may apply. Wikipedia® is a registered trademark of the Wikimedia Foundation.     Privacy policy About Wikipedia Disclaimers Mobile view   . . Tire factories start with bulk raw materials such as rubber. Please help improve it by rewriting it in an encyclopedic style. and the overall business model. Unsourced material may be challenged and removed. the manufacturing processes and machinery. (April 2009) Pneumatic tires are manufactured according to relatively standardized processes and machinery. This article describes the components assembled to make a tire. search This article is written like a personal reflection or essay rather than an encyclopedic description of the subject. the free encyclopedia Jump to: navigation. . and chemicals and produce numerous specialized components that are assembled and cured. With over 1 billion tires manufactured worldwide annually. (July 2012) This article needs additional citations for verification. the tire industry is the major consumer of natural rubber.Tire manufacturing From Wikipedia. carbon black. the various materials used. Please help improve this article by adding citations to reliable sources. in around 450 tire factories in the world. Typical components used in tire assembly are listed below.4 Curing o 11.5 Final finish 12 Tire manufacturing companies 13 See also 14 References 15 External links . Heat facilitates a polymerization reaction that crosslinks rubber monomers to create long elastic molecules. Contents                1 Inner liner 2 Body ply 3 Sidewall 4 Beads 5 Apex 6 Belt package 7 Tread 8 Cushion gum 9 Other components 10 Materials 11 Manufacturing process o 11.The tire is an assembly of numerous components that are built up on a drum and then cured in a press under heat and pressure.3 Tire building o 11. These polymers create the elastic quality that permits the tire to be compressed in the area where the tire contacts the road surface and spring back to its original shape under high-frequency cycles.2 Component preparation o 11.1 Compounding and mixing o 11. Additives used in sidewall compounds include antioxidants and antiozonants. Alternatively called "filler" (as in the diagram above). The inner liner assures that the tire will hold high-pressure air inside. which improves bonding of the bead to the rubber.Inner liner The inner liner is an extruded halobutyl rubber sheet compounded with additives that result in low air permeability.[1] Body ply The body ply is a calendered sheet consisting of one layer of rubber. and Kevlar. Belt package . Beads are inflexible and inelastic. The earliest textile used was cotton. one layer of reinforcing fabric. Passenger tires typically have one or two body plies. and aircraft tires have progressively more plies. and provide the mechanical strength to fit the tire to the wheel. Coatings protect the steel from corrosion. Body plies give the tire structure strength. The apex provides a cushion between the rigid bead and the flexible inner liner and body ply assembly. Bead wire is coated with special alloys of bronze or brass. later materials include rayon. nylon. Truck tires. Sidewall Sidewalls are non-reinforced extruded profiles with additives to give the sides of the tire good abrasion resistance and environmental resistance. Sidewall extrusions are nonsymmetrical and provide a thick rubber area to enable molding of raised letters and sidewall ornamentation. and a second layer of rubber. The fabric cords are highly flexible but relatively inelastic. Beads Beads are bands of high tensile-strength steel wire encased in a rubber compound. off-road tires. Copper in the alloy and sulfur in the rubber cross-link to produce copper sulfide. without the air gradually diffusing through the rubber structure. Apex The apex is a triangular extruded profile that mates against the bead. Bead rubber includes additives to maximize strength and toughness. polyester. Materials     Natural rubber. and at opposing angles in bias tire construction. and a second layer of rubber. because of its low air permeability. Bromobutyl is superior to chlorobutyl. a layer of closely spaced steel cords. as hard compounds have long wear characteristics but poor traction whereas soft compounds have good traction but poor wear characteristics. Other components Tire construction methods vary somewhat in the number and type of components. Cushion gum Many higher-performing tires include an extruded component between the belt package and the tread to isolate the tread from mechanical wear from the steel belts. Tire makers continuously introduce new materials and construction methods in order to achieve higher performance at lower cost. Passenger tires are usually made with two or three belts. The steel cords are oriented radially in radial tire construction.Belts are calendered sheets consisting of a layer of rubber. or polyisoprene is the basic elastomer used in tire making Styrene-butadiene co-polymer (SBR) is a synthetic rubber which is often substituted in part for natural rubber based on the comparative raw materials cost Polybutadiene is used in combination with other rubbers because of its low heat-buildup properties Halobutyl rubber is used for the tubeless inner liner compounds. Belts give the tire strength and dent resistance while allowing it to remain flexible. as well as the compound formulations for each component. Tread The tread is a thick extruded profile that surrounds the tire carcass. Tread compounds include additives to impart wear resistance and traction in addition to environmental resistance. but is more expensive . Tread compound development is an exercise in compromise. The halogen atoms provide a bond with the carcass compounds which are mainly natural rubber. according to the tire use and price point. carbon 220 50 k. Each component has a different mix of ingredients according to the properties required for that component. The sheet is pulled off the rollers in the form of a strip. and laid down into a pallet bin. A mill consists of twin counter-rotating rolls. dusted with talc. Alternatively. 5. The strip is cooled.g. The main one is zinc oxide Antioxidants and antiozonants prevent sidewall cracking due to the action of sunlight and ozone Textile fabric reinforces the carcass of the tire Manufacturing process Tire plants are traditionally divided into five departments that perform special operations. The mixing is done in three or four stages to incorporate the ingredients in the desired order.g. 2. accelerator 1. Large tire makers may set up independent factories on a single site.g. Internal mixers are often equipped with two counter-rotating rotors in a large housing that shear the rubber charge along with the additives. These usually act as independent factories within a factory. Oil 3. 3. used together with carbon black in high performance tires.       Carbon Black.2 k. one serrated. Mixing is the process of applying mechanical work to the ingredients in order to blend them into a homogeneous substance.5 k.g. The shearing action generates considerable heat. so both rotors and housing are water-cooled to maintain a temperature low enough to assure that vulcanization does not begin. or cluster the factories locally across a region. . forms a high percentage of the rubber compound. After mixing. as a low heat build up reinforcement Sulphur crosslinks the rubber molecules in the vulcanization process Vulcanizing Accelerators are complex organic compounds that speed up the vulcanization Activators assist the vulcanization.g.5 k. zinc oxide 2. Compounding is the operation of bringing together all the ingredients required to mix a batch of rubber compound. that provide additional mechanical working to the rubber and produce a thick rubber sheet. the rubber charge is dropped into a chute and fed by an extruding screw into a roller die. 6. This gives reinforcement and abrasion resistance Silica.g.5 k. the batch can be dropped onto an open rubber mill batchoff system. Compounding and mixing SB R rubber compound to with chemicals formulations 1. SB Rubber 100 k. 4. static acid 1. A creel room is a facility that houses hundreds of fabric or wire spools that are fed into the calender. and a die. Tire treads are often extruded with four components in a quadraplex extruder. and sidewalls are wrapped around the drum. extrusion. Splices that are too light or . As a result. Belts are spliced end to end with no overlap. Tirebuilding machines (TBM) can be manually operated or fully automatic. Fabric calenders produce an upper and lower rubber sheet with a layer of fabric in between. and the assembly turned up over the bead. Calenders are used to produce body plies and belts. Extrusion is also used for sidewall profiles and inner liners. along with a few clumps of carbon black elsewhere. Calenders utilize downstream equipment for shearing and splicing calendered components. excessive rotor clearance. and the mixing terminated upon reaching a specified total amount of mix energy imparted to the batch. Steel calenders do so with steel cords. that are not well mixed with the rubber or the additives. This is due to several causes. Component preparation Components fall into three classes based on manufacturing process: calendering. Mixers are often controlled according to the power integration method. Splices that are too heavy or non-symmetrical will generate defects in force variation. The extruder applies two conditions to the compound: heat and pressure. In the second stage operation the belt package and tread are applied and the green tire is inflated and shaped. The extruder screw also provides for additional mixing of the compound through the shearing action of the screw. usually of the order of 2 metres wide. where the current flow to the mixer motor is measured. Typical TBM operations include the first-stage operation. The extruder machine consists of a screw and barrel. however in practice there is considerable non-uniformity to the dispersion. heaters. where the joining ends are bevel-cut. balance. and a little less there.The ideal compound at this point would have a highly uniform material dispersion. core compound. tread compound. Inner liner and body plies are spliced with a square-ended overlap. The calender is a set of multiple large-diameter rolls that squeeze rubber compound into a thin sheet. and either rolled up on a spool or cut to length. The compound is pushed through a die. or bulge parameters. where inner liner. and bead building. the beads are placed. screw drive. rotor wear. including hot and cold spots in the mixer housing and rotors. there can be a little more carbon black here. cooled to terminate the vulcanization process. Tread and sidewall are joined with a skived splice. All components require splicing. and poorly circulating flow paths. Tire building Tire building is the process of assembling all the components onto a tire building drum. one with four screws processing four different compounds. after which the extruded profile is vulcanized in a continuous oven. usually a base compound. and wing compound. body plies. Nevertheless there is a large base of machine builders who produce tire-building machines. Large off-road tires are often cured in ovens with cure times approaching 24 hours. The bladder is filled with a recirculating heat transfer medium. high production yield. In this process the green tire is automatically transferred onto the lower mold bead seat. This permits the equipment to build different tire sizes in consecutive operations without the need to change tooling or setups. and reduced labor. Curing Curing is the process of applying pressure to the green tire in a mold in order to give it its final shape. Tire balance measurement is a test where the tire is automatically placed on wheel halves. There are two generic mold types. mechanical and hydraulic. Large commercial truck/bus tires. two-piece molds and segmental molds. Pirelli Tire developed a special process called MIRS that uses robots to position and rotate the building drums under stations that apply the various components. a rubber bladder is inserted into the green tire. and lock the mold with a breech-lock mechanism. taking on the tread pattern and sidewall lettering engraved into the mold. rotated at a high speed and measured for imbalance. such as steam. Temperatures are in the area of 350 degrees Fahrenheit with pressures around 350 PSI. while hydraulic presses use hydraulic oil as the prime mover for machine motion. and the mold closes while the bladder inflates. Hydraulic presses have emerged as the most costeffective because the press structure does not have to withstand the mold-opening pressure and can therefore be relatively lightweight. The largest tire makers have internally developed automated tire-assembly machines in an effort to create competitive advantages in tire construction precision. As the mold closes and is locked the bladder pressure increases so as to make the green tire flow into the mold. inflated. hot water. or inert gas. and the tire stripped out of the mold. usually via extrusion and strip winding methods. The tire may be placed on a PCI. At the end of cure the pressure is bled down. Mechanical presses hold the mold closed via toggle linkages. and applying heat energy to stimulate the chemical reaction between the rubber and other materials. This process is well suited to small volume production with frequent size changes. there are several additional operations. The final product of the TBM process is called a green tire. are inspected by X-ray machines that can penetrate the rubber to analyze the steel cord structure. the mold opened. or postcure inflator. where green refers to the uncured state. run against a simulated road surface.open can lead to visual defects and in some cases tire failure. Tire uniformity measurement is a test where the tire is automatically mounted on wheel halves. . Final finish After the tire has been cured. that will hold the tire fully inflated while it cools. Passenger tires cure in approximately 15 minutes. There are two generic curing press types. and measured for force variation. as well as some passenger and light truck tires. exposed cords. tires are inspected by human eyes for numerous visual defects such as incomplete mold fill.html External links  The Tire Society View page ratings Rate this page What's this? Trustworthy Objective Complete Well-written I am highly knowledgeable about this topic (optional) Categories:           Tire manufacturers Tires Manufacturing Create account Log in Article Talk Read Edit View history . See also  Retread References 1.In the final step. and others. blemishes. List of tire companies.com/about/diversity/how_built. ^ http://www.goodyeartires. blisters. Tire manufacturing companies For a list of tire companies. Contact us Privacy policy About Wikipedia Disclaimers Mobile view        .. additional terms may apply. Inc. Wikipedia® is a registered trademark of the Wikimedia Foundation. a non-profit organization.      Main page Contents Featured content Current events Random article Donate to Wikipedia Interaction      Toolbox Print/export Languages    Help About Wikipedia Community portal Recent changes Contact Wikipedia Magyar This page was last modified on 26 July 2012 at 11:06. Text is available under the Creative Commons Attribution-ShareAlike License. See Terms of use for details.