- Tires are made from a combination of rubber, fabric (e.g. polyester, nylon and rayon) and steel. Steel bead wires form the structure of the tire. Corded fabric and/or steel is encased in rubber and formed into sheets (plies) that wrap around the bead wires. The more plies there are, the stronger the tire is and the more weight the car can hold. On top of the plies are the rubber treads, designed with different patterns and depths to suit different vehicles or road and weather conditions. A soft, thin rubber liner inside the tire helps prevent air leaks. Cars must be fitted with the correct tire size and the tire must be balanced properly and inflated to the correct specification to ensure maximum performance, wear and safety.
- Unlike tires of the past, modern tires do not contain an inner tube that inflates. Instead the tire is fitted to the rim to form a leakproof chamber, which is filled with air through a valve stem in the rim.
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Cutaway of tire plies, c1970 Alexander Duduk, Wikimedia CommonsThe first known tire was a simple steel band that held the wood spokes of a wagon or cart wheel in place and provided a better wearing surface for the wheel. In the late nineteenth century, pneumatic (air-filled) tires were developed. The inner tube style gave way to tubeless tires in the mid-twentieth century. Traditional tubeless tires were bias ply (14,16), where fabric or steel plies were laid out over steel bead wires (18,19) in a crisscross pattern, diagonal to the center tread (C). Modern tires now employ the radial ply method (10,12), where sidewall plies wrap around the wheel, running parallel to each other but perpendicular to the tire tread centerline. On top of that, layers of stabilizer belts form a circle around the tire, directly underneath the tread centerline. This radial ply method provides better traction, more even tread wear and a softer ride. - The sidewall of a tire is labeled with three numbers that indicate the size of the tire (e.g. 225/50R16). The first number is the width of the tire in millimeters at its widest point from outer sidewall to inner sidewall. The second number tells us that the height of the sidewall from rim to tread, and is read as a percentage. In this example, it is 50 percent of the tire's width. The higher the percentage, the taller the sidewall. The third number is the diameter of the wheel rim the tire should be fitted to. Letter designations on the sidewall can indicate whether it is a passenger vehicle (P) or light truck (LT), and in this example the "R" indicates a radial tire.
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Low profile performance tire, c2008 John De Boer, stock xchng.There are a variety of tire types to suit performance, comfort and traction needs. Most passenger cars use all-weather tires with treads designed to work on a variety of road conditions, but deeper, wider spaced tread snow tires are also available for extreme winter climates. Higher profile (high sidewall) tires provide a more comfortable ride and are available in smooth ride and low-noise tread patterns. Performance tires have lower profiles and larger tire widths to provide better traction and turning capabilities, with some compromise on ride comfort. High performance racing tires also employ sidewall stabilizing layers and maximum road contact treads for the best speed, traction and handling options. Tires also come in different aesthetic styles, such as white walls or with raised lettering to create a special custom look. - Tires that have worn or uneven tread lead to reduced traction, braking and steering control, particularly in rain, ice or snowy conditions. Tires are dangerously worn when there is only 2/32 of an inch of tread left. However, for increased safety you may want to replace at 4/32 or 6/32 for snowy conditions.
Comments
kmobigplanet said
on 4/1/2009 good stuff 5*****