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A tire (British tyre) is a roughly toroidal piece of, usually, rubber placed on a wheel to cushion it. Tires generally have reinforcing threadss in them; based on the orientation of the threads, they are classified as bias-ply or radial. A tire may have an inner tube or not. Air filled tires are known as pneumatic tires, and these are the type in almost universal use today. The air compresses as the wheel goes over a bump and acts as a shock absorber. Attempts have been made to make various types of solid tire but none has so far met with much success.

Tire maufacturing companies include:

Table of contents
1 History
2 Train tires
3 See also
4 External link


For most of history wheels had very little in the way of shock absorption and journeys were very bumpy and uncomfortable. The modern tire came about in stages in the 19th century.

In 1844, Charles Goodyear invented vulcanized rubber, the material that would later be used to produce tires.

John Boyd Dunlop, a vetinary surgeon living in Belfast Ireland, is widely recognized as the father of the modern tire, although he was not the first to come up with the idea.

In 1845 the first vulcanised rubber pneumatic (inflatable) tire was patented by Scottish engineer Robert William Thompson as the Aerial Wheel. This invention consisted of a canvas inner tube surrounded by a leather outer tire. The tire gave a good ride, but there were so many manufacturing and fitting problems that the idea had to be abandoned.

John Dunlop re-invented the tire for his ten year old son's tricycle in 1887 and was awarded a patent for his tire in 1888. Dunlop's tire had a modified leather hosepipe as an inner tube and rubber treads. It wasn't long before rubber inner tubes were invented.

Because neither bicycles nor automobiles had been invented when Thompson produced his tire, that tire was only applied to horse drawn carriages. By Dunlop's time, the bicycle had been fully developed (see Rover) and it proved a far more suitable application for pneumatic tires.

Dunlop partnered with Harvey du Cross, Jr to form a company which later became the Dunlop Rubber Company to produce his invention. The invention quickly caught on for bicycles and was later adapted for use on carss. Dunlop's company has since merged with the Goodyear company.

Train tires

The steel wheels of trains have tires too, steel tires.

(Some trains, mostly Metros, have rubber tires, including some lines of the Paris Metro, and the Montreal Metro).

Efficient though the rolling of steel wheel on steel rail is, wear still takes place - on acceleration, on braking, and on cornering. As well as the simple wearing away of the wheel surface, a wheel that wears begins to deviate from the correct profile. The shape of a train wheel is designed and specified precisely for the best possible riding and cornering characteristics, and too much wear can alter that. Wear can also take place unevenly if wheels lock up under heavy braking, causing flat spots.

Another, different form of damage to a train's wheels takes place if violent wheelslip occurs. The friction so caused can heat the wheel (and rail) enough to cause permanent heat damage.

Replacing a whole wheel because of a worn contact surface proves expensive, so the concept of fitting steel tires to train wheels came about. The tire is a hoop of steel that's fitted around the steel or iron wheel. No obvious form of fastening is generally used to attach it. Instead, the tire is held by an interference fit - it's made slightly smaller than the wheel on which it is supposed to fit. To fit a tire, it's heated up until it's glowing hot. Railroad workshops generally have special equipment to do so. As the tire heats, it expands until it's big enough to fit around the wheel. After placing it on the wheel, the tire is cooled, and it shrink fits onto the wheel. When cold, the tire won't budge even under quite extreme forces.

Removing a tire is done in reverse - the tire is heated while on the wheel until it loosens.

Tires are reasonably thick, up to about an inch thick or more, giving plenty of room to wear. If a tire wears out of shape, or gets flat-spotted, but has a reasonable amount of metal left, it can be turned on a wheel lathe to refinish it, reshaping it to the correct profile.

See also

External link