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Inspection and maintenance of tires is about inspecting for wear and damage on tires so that adjustments or measures can be made to take better care of the tires so that they last longer, or to detect or predict if repairs or replacement of the tires becomes necessary. Tire maintenance for motor vehicles is based on several factors. The chief reason for tire replacement is friction from moving contact with road surfaces, causing the tread on the outer perimeter of tires to eventually wear away. When the tread depth becomes too shallow, like for example below 3.2 mm (4/32 in), the tire is worn out and should be replaced. The same rims can usually be used throughout the lifetime of the car. Other problems encountered in tire maintenance include:
Sometimes a pneumatic tire gets a hole or a leak through which the air inside leaks out resulting in a flat tire, a condition which must be fixed before the car can be driven safely.
Vehicles typically carry a spare tire, already mounted on a wheel rim, to be used in the event of a flat tire or blowout. Spare tires (sometimes called "doughnuts") for modern cars are smaller than regular tires (to save trunk space, weight and cost) and should not be used to drive very far before replacement with a full-size tire. A few vehicle models use conventional size spare tires. Jacks and lug wrenches for emergency replacement of a flat tire with a spare are included with a new car. Not included, but available separately, are hand or foot pumps (like a bicycle pump) for filling a tire with air by the vehicle owner. Cans of pressurized air can sometimes be bought separately for convenient emergency refill of a tire.
Some cars and trucks are equipped with run flat tires that may be driven with a puncture over a distance of 80 km to 100 km. This eliminates the need for an immediate stop and tire change or calling for roadside assistance.
On dry surfaces, tires have more traction when they are bald, because there is more surface area making contact with the road. The reason regular tires have treads is to avoid hydroplaning when the surface of the road is wet. Therefore racing cars competing in dry conditions characteristically use tires without treads, often known as slicks. For example stock cars driven on professionally maintained NASCAR tracks use tires without treads, and with a thicker layer of rubber.
Front tires, especially on front wheel drive vehicles, have a tendency to wear out more quickly than rear tires. Routine maintenance including tire rotation (exchanging the front and rear tires with each other) is often done periodically to facilitate uniform tire wear.
There are simple hand-held tire-pressure gauges which can be temporarily attached to the valve stem to check a tire's interior air pressure. This measurement of tire inflation pressure should be made at least once a month. Since heat in the tires from driving can impact the temperature a lot, accurate readings can only be obtained when the tires are cold - that is at least three hours after the vehicle has been driven or driven less than 1 km (1/2 mi) since cold - tire pressures will not then be higher because of operating heat. The recommended inflation pressure is found in the owner's manual and on the vehicle's tire placard. Because of slow air leaks, changes in the weather and ambient temperature or other conditions, tire pressure will occasionally have to be corrected via the valve stem with compressed air which is often available at service stations.
Under-inflation of tires can cause premature and uneven tire wear, excess fuel usage, and carries an increased risk of explosive failure (blowout) especially after prolonged high speed operation at high temperatures. Overall, these factors decrease the life of a tire by up to 20%.Many vehicles have tire pressure monitoring systems; older cars are usually equipped with indirect monitoring systems while later cars are typically equipped with direct tire pressure monitoring systems.
It is extremely important for owners to have an understanding of what is safe and what is not when it comes to their tires. The three major areas to keep an eye on is the tread, sidewall, and air pressure of the tire. Having the correct air pressure in your vehicle's tires lets your vehicle perform in the most efficient way possible. When objects such as a screw or nail puncture a tire, it creates a small leak in the tire. This leads to under-inflation of the tire. When a tire is under-inflated, it causes the inside of the tire to heat up. This heat compromises the internal structure of the tire which can lead to a blowout. When a tire is over-inflated, it wears the tread down faster, and becomes more prone to catching nails or screws in the tire. The best way to check tire maintenance is to check the air pressure, because that will lead you to whatever problem your tire might have. There are several factors that may cause quicker tire wear, among them there are heavy braking and fast cornering, constant heavy cargo transportation and rough roads, improper pressure (under- or overinflation) or improper maintenance.[ clarification needed ] That's why for the older vehicles, that do not come equipped with TPMS sensors, it is highly recommended to check tire pressure at least once a month (National Highway Traffic Safety Administration recommendation).
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, which also provide a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over by providing a bearing pressure that will not deform the surface excessively.
A racing slick or slick tyre is a type of tyre that has a smooth tread used mostly in auto racing. The first production slick tyre was developed by M&H Tires in the early 1950s for use in drag racing. By eliminating any grooves cut into the tread, such tyres provide the largest possible contact patch to the road, and maximize dry traction for any given tyre dimension; see Performance. Slick tyres are used on race tracks and in road racing, where acceleration, steering and braking require maximum traction from each wheel. Slick tyres are typically used on only the driven (powered) wheels in drag racing, where the only concern is maximum traction to put power to the ground, and are not used in rallying.
Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or other wheeled vehicle occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. If it occurs to all wheels simultaneously, the vehicle becomes, in effect, an uncontrolled sled. Aquaplaning is a different phenomenon from when water on the surface of the roadway merely acts as a lubricant. Traction is diminished on wet pavement even when aquaplaning is not occurring.
The Tweel is an airless tire design developed by the French tire company Michelin. Its significant advantage over pneumatic tires is that the Tweel does not use a bladder full of compressed air, and therefore cannot burst, leak pressure, or become flat. Instead, the Tweel's hub is connected to the rim via flexible polyurethane spokes which fulfil the shock-absorbing role provided by the compressed air in a traditional tire.
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation of the wheel, roadbed, etc., is recovered when the pressure is removed. Two forms of this are hysteresis losses, and permanent (plastic) deformation of the object or the surface. Note that the slippage between the wheel and the surface also results in energy dissipation. Although some researchers have included this term in rolling resistance, some suggest that this dissipation term should be treated separately from rolling resistance because it is due to the applied torque to the wheel and the resultant slip between the wheel and ground, which is called slip loss or slip resistance. In addition, only the so-called slip resistance involves friction, therefore the name "rolling friction" is to an extent a misnomer.
A beadlock or bead lock is a mechanical device that secures the bead of a tire to the wheel of a vehicle. Tires and wheels are designed so that when the tire is inflated, the tire pressure pushes the bead of the tire against the inside of the wheel rim so that the tire stays on the wheel and the two rotate together. In situations where tire pressure is insufficient to hold the bead of the tire in place, a beadlock is needed.
BFGoodrich is an American tire company. Originally part of the industrial conglomerate Goodrich Corporation, it was acquired in 1990 by the French tire maker Michelin. BFGoodrich was the first American tire manufacturer to make radial tires. It made tires for the then new Winton car from Winton Motor Carriage Company.
A run-flat tire is a pneumatic vehicle tire designed to resist the effects of deflation when punctured, allowing the vehicle to continue to be driven at reduced speeds for limited distances. First developed by tire manufacturer Michelin in the 1930s, run-flat tires were introduced to the public market in the 1980s. They have increased in popularity over time.
Automotive tires are described by an alphanumeric tire code or tyre code, which is generally molded into the sidewall of the tire. This code specifies the dimensions of the tire, and some of its key limitations, such as load-bearing ability, and maximum speed. Sometimes the inner sidewall contains information not included on the outer sidewall, and vice versa.
A tire-pressure monitoring system (TPMS) monitors the air pressure inside the pneumatic tires on vehicles. A TPMS reports real-time tire-pressure information to the driver, using either a gauge, a pictogram display, or a simple low-pressure warning light. TPMS can be divided into two different types – direct (dTPMS) and indirect (iTPMS).
A flat tire is a deflated pneumatic tire, which can cause the rim of the wheel to ride on the tire tread or the ground potentially resulting in loss of control of the vehicle or irreparable damage to the tire. The most common cause of a flat tire is puncturing of the tire by a sharp object, such as a nail or pin, letting the air escape. Depending on the size of the puncture, the tire may deflate slowly or rapidly.
Airless tires, non-pneumatic tires (NPT), or flat-free tires are tires that are not supported by air pressure. They can be used on small vehicles such as ride-on lawn mowers and motorized golf carts. They also are used on heavy equipment required to operate on sites where risk of tire punctures is high. Tires composed of closed-cell polyurethane foam are also made for bicycles and wheelchairs.
A tubeless tire is a pneumatic tire that does not require a separate inner tube.
A spare tire is an additional tire carried in a motor vehicle as a replacement for one that goes flat, has a blowout, or has another emergency. Spare tire is generally a misnomer, as almost all vehicles actually carry an entire wheel with a tire mounted on it as a spare rather than just a tire, as fitting a tire to a wheel would require a motorist to carry additional, specialized equipment. However, some spare tires are not meant to be driven long distances. Space-savers have a maximum speed of around 50 mph (80 km/h).
A bicycle tire is a tire that fits on the wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for racing. Bicycle tires provide an important source of suspension, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically the second largest source, after wind resistance, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle.
The Michelin PAX is an automobile run-flat tire system that utilizes a special type of rim and tire to allow temporary use of a wheel if its tire is punctured. The core of Michelin's PAX system is the semi-rigid ring installed onto the rim using special equipment. It provides support to the tire and its sidewall to allow emergency operation at limited speed until such time as the tire can be replaced. Cars that use the system include supercars like the Bugatti Veyron EB 16.4, luxury cars like the Rolls-Royce Phantom, and more common vehicles like the Honda Odyssey and Nissan Quest.
A flat spot, or wheel flat, also called spalling or shelling, is a fault in railroad wheel shape. A flat spot occurs when a rail vehicle's wheelset is dragged along the rail after the wheel/axle has stopped rotating. Flat spots are usually caused by use of the emergency brake, or slip and slide conditions that cause wheels to lock up while the train is still moving. Flat spots are more common in the autumn and winter when the rails are slippery. Flat spots can also be caused by faulty brakes or wheelset bearings.
Direct TPMS, or direct tire pressure monitoring systems refers to the use of a pressure sensor directly mounted on the wheels or tires of a vehicle. The pressure inside the tire is measured using a pressure transducer with the pressure information being subsequently sent to the vehicle to warn the driver of under or over inflation of a tire. The pressure information is commonly transmitted to the vehicle using radio frequency (RF) technology, though systems using mechanical, electrical or magnetic methods have been used over recent years.
The following outline is provided as an overview of and topical guide to tires:
Stemco is a Longview, Texas, based company that manufactures and distributes products for the global commercial vehicle market. Its major product categories include wheel end products, brake products, intelligent transportation systems and suspension components.