Car Tires

Definition: Hoop that covers a wheel "automobile tires are usually made of rubber and filled with compressed air"

A tire is a strong, flexible rubber casing attached to the rim of a wheel. Tires provide a gripping surface for traction and serve as a cushion for the wheels of a moving vehicle. Tires are found on automobiles, trucks, buses, aircraft landing gear, tractors and other farm equipment, industrial vehicles such as forklifts, and common conveyances such as baby carriages, shopping carts, wheel chairs, bicycles, and motorcycles.

Tires for most vehicles are pneumatic; air is held under pressure inside the tire. Scottish inventor Robert Thomson developed the pneumatic tire with inner tube in 1845, but his design was ahead of its time and attracted little interest. The pneumatic tire was reinvented in the 1880s by another Scotsman, John Boyd Dunlop, and became immediately popular with bicyclists. In modern times, pneumatic tires are designed to form a pressure seal with the rim of the wheel.

Natural rubber is the main raw material used in manufacturing tires, although synthetic rubber is also used. In order to develop the proper characteristics of strength, resiliency, and wear-resistance, however, the rubber must be treated with a variety of chemicals and then heated. American inventor Charles Goodyear, once again, discovered the process of strengthening rubber, known as vulcanization or curing, by accident in 1839. He had been experimenting with rubber since 1830 but had been unable to develop a suitable curing process. During an experiment with a mixture of india rubber and sulfur, Goodyear dropped the mixture on a hot stove. A chemical reaction took place and, instead of melting, the rubber-sulfur mixture formed a hard lump. He continued his experiments until he could treat continuous sheets of rubber.