A tire (in American English and Canadian English) or tyre (in British English, Australian English and others) 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 in order to prevent wear and tear. Today, the vast majority of tires are pneumatic, 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 bicycles, motorcycles, cars, trucks, earthmovers, and aircraft.

Etymology and spelling

The Oxford English Dictionary suggests that the word derives from "attire", while other sources suggest a connection with the verb "to tie". From the 15th to the 17th centuries the spellings tire and tyre were used without distinction; but by 1700 tyre had become obsolete and tire remained as the settled spelling. 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. 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", 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". However, over the course of the 20th century tyre became established as the standard British spelling.

Iron tires

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.[citation needed]

Rubber tires

The first practical pneumatic tire was made by John Boyd Dunlop, born in Scotland, while working as a veterinarian in May Street, Belfast, 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]

Pneumatic tires are made of a flexible elastomer material, such as rubber, with reinforcing materials such as fabric and wire. Tire companies were first started in the early 20th century, and grew in tandem with the auto industry. Today, over 1 billion tires are produced annually, in over 400 tire factories, with the three top tire makers commanding a 60% global market share.

Manufacturing

Pneumatic tires are manufactured according to relatively standardized processes and machinery, in around 450 tire factories in the world. Over 1 billion tires are manufactured annually, making the tire industry the majority consumer of natural rubber. Tire factories start with bulk raw materials such as rubber, carbon black, and chemicals and produce numerous specialized components that are assembled and cured. This article describes the components assembled to make a tire, the various materials used, the manufacturing processes and machinery, and the overall business model.

The biggest tyre manufacturers (by revenue) are Bridgestone, Michelin, Good Year and Continental AG.[9]