The tire provides a cushion between the vehicle and the road to reduce the transmission of road shocks. It also provides friction to allow the vehicle perform its normal operations.
Modern tyres are manufactured from a range of materials. The rubber is mainly synthetic.
Two types of tire construction are common - cross-ply and radial.
Most passenger cars now use radial tires, as do most 4-wheel-drives and heavy vehicles.
Tube tires require an inner tube to seal the air inside the tire.
Tubeless tires eliminate the inner tube by making the complete wheel and tire assembly air-tight.
A special, air-tight valve assembly is needed. This can be a tight fit into the rim, or it can be held with a nut and sealing washers.
Tires can be identified by markings on the sidewalls. This typically includes the maker’s name, the rim size, the type of tire construction, aspect ratio, maximum load and speed, and, in some cases, intended use.
Regulations cover the allowable dimensions for wheels and tires on a particular vehicle. These dimensions are usually set out on the tire placard attached to the vehicle.
Incorrectly selected wheels and tires can overload wheel bearings and change steering characteristics. The tire placard lists the wheel and tire sizes approved by the manufacturer for the vehicle. Using other wheels and tires may be illegal.
List allowable tire and wheel sizes for 3 different vehicles, using the tire placard recommendations.
Source: CDX Global
