Tire
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
The materials of modern pneumatic tires are synthetic rubber, natural rubber, fabric, and wire, along with carbon black and other chemical compounds. They consist of a tread and a body. The tread provides traction while the body provides containment for a quantity of compressed air. Before rubber was developed, tires were metal bands fitted around wooden wheels to hold the wheel together under load and to prevent wear and tear. Early rubber tires were solid. Pneumatic tires are used on many vehicles, including cars, bicycles, motorcycles, buses, trucks, heavy equipment, and aircraft. Metal tires are used on locomotives and railcars, and solid rubber tires are also used in various non-automotive applications, such as casters, carts, lawnmowers, and wheelbarrows.
Unmaintained tires can lead to severe hazards for vehicles and people, ranging from flat tires making the vehicle inoperable to blowouts, where tires explode during operation and possibly damage vehicles and injure people. The manufacture of tires is often highly regulated for this reason. Because of the widespread use of tires for motor vehicles, tire waste is a substantial portion of global waste. There is a need for tire recycling through mechanical recycling and reuse, such as for crumb rubber and other tire-derived aggregate, and pyrolysis for chemical reuse, such as for tire-derived fuel. If not recycled properly or burned, waste tires release toxic chemicals into the environment. Moreover, the regular use of tires produces micro-plastic particles that contain these chemicals that both enter the environment and affect human health.
Etymology and spelling
The word tire is a short form of attire, from the idea that a wheel with a tire is a dressed wheel.Tyre is the oldest spelling, and both tyre and tire were used during the 15th and 16th centuries. During the 17th and 18th centuries, tire became more common in print. The spelling tyre did not reappear until the 1840s when the English began shrink-fitting railway car wheels with malleable iron. Nevertheless, many publishers continued using tire. The Times newspaper in London was still using tire as late as 1905. The spelling tyre began to be commonly used in the 19th century for pneumatic tires in the UK. The 1911 edition of the Encyclopædia Britannica states that "The 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 describes that "there is nothing to be said for 'tyre', which is etymologically wrong, as well as needlessly divergent from our own older & the present American usage". However, over the 20th century, tyre became established as the standard British spelling.
History
The earliest tires were bands of leather in Sumer, then iron placed on wooden wheels used on carts and wagons. A skilled worker, known as a wheelwright, would cause the tire to expand by heating it in a forge fire, placing it over the wheel, and quenching it, causing the metal to contract back to its original size to fit tightly on the wheel.The first patent for what appears to be a standard pneumatic tire appeared in 1847 and was lodged by Scottish inventor Robert William Thomson. However, this idea never went into production. The first practical pneumatic tire was made in 1888 on May Street, Belfast, by Scots-born John Boyd Dunlop, owner of one of Ireland's most prosperous veterinary practices. It was an effort to prevent the headaches of his 10-year-old son Johnnie while riding his tricycle on rough pavements. His doctor Sir John Fagan, had prescribed cycling as an exercise for the boy and was a regular visitor. Fagan participated in designing the first pneumatic tires. Cyclist Willie Hume demonstrated the supremacy of Dunlop's tires in 1889, winning the tire's first-ever races in Ireland and then England. In Dunlop's tire patent specification dated 31 October 1888, his interest is only in its use in cycles and light vehicles. In September 1890, he was made aware of an earlier development, but the company kept the information to itself. In 1892, Dunlop's patent was declared invalid because of the prior art by forgotten fellow Scot Robert William Thomson of London. However, Dunlop is credited with "realizing rubber could withstand the wear and tear of being a tire while retaining its resilience". John Boyd Dunlop and Harvey du Cros worked through the ensuing considerable difficulties. They employed inventor Charles Kingston Welch and acquired other rights and patents, which allowed them some limited protection of their Pneumatic Tyre business's position. Pneumatic Tyre would become Dunlop Rubber and Dunlop Tyres. The development of this technology hinged on myriad engineering advances, including the vulcanization of natural rubber using sulfur, as well as the development of the "clincher" rim for holding the tire in place laterally on the wheel rim.
In 1895, Michelin created the world's first pneumatic tyres for automobiles, using them in a car called L'Eclair competing in the 1895 Paris-Bordeaux-Paris race.
Synthetic rubbers were invented in the laboratories of Bayer in the 1920s. Rubber shortages in the United Kingdom during WWII prompted research on alternatives to rubber tires with suggestions including leather, compressed asbestos, rayon, felt, bristles, and paper.
In 1946, Michelin developed the radial tire method of construction. Michelin had bought the bankrupt Citroën automobile company in 1934 to utilize this new technology. Because of its superiority in handling and fuel economy, use of this technology quickly spread throughout Europe and Asia. In the US, the outdated bias-ply tire construction persisted until the Ford Motor Company adopted radial tires in the early 1970s, following a 1968 article in an influential American magazine, Consumer Reports, highlighting the superiority of radial construction. The US tire industry lost its market share to Japanese and European manufacturers, which bought out US companies.
Applications
Tires may be classified according to the type of vehicle they serve. They may be distinguished by the load they carry and by their application, e.g. to a motor vehicle, aircraft, or bicycle.Automotive
Light–medium duty
Light-duty tires for passenger vehicles carry loads in the range of on the drive wheel. Light-to-medium duty trucks and vans carry loads in the range of on the drive wheel. They are differentiated by speed rating for different vehicles, including : winter tires, light truck tires, entry-level car tires, sedans and vans, sport sedans, and high-performance cars. Apart from road tires, there are special categories:- Snow tires are designed for use on snow and ice. They have a tread design with larger gaps than those on summer tires, increasing traction on snow and ice. Such tires that have passed a specific winter traction performance test are entitled to display a "Three-Peak Mountain Snow Flake" symbol on their sidewalls. Tires designed for winter conditions are optimized to drive at temperatures below. Some snow tires have metal or ceramic studs that protrude from the tire to increase traction on hard-packed snow or ice. Studs abrade dry pavement, causing dust and creating wear in the wheel path. Regulations that require the use of snow tires or permit the use of studs vary by country in Asia and Europe, and by state or province in North America.
- All-season tires are typically rated for mud and snow. These tires have tread gaps that are smaller than snow tires and larger than conventional tires. They are quieter than snow tires on clear roads, but less capable on snow or ice.
- All-terrain tires are designed to have adequate traction off-road, yet have benign handling and noise characteristics for highway driving. Such tires are rated better on snow and rain than street tires and "good" on ice, rock, and sand.
- Mud-terrain tires have a deeper, more open tread for good grip in mud, than all-terrain tires, but perform less well on pavement.
- High-performance tires are rated for speeds up to and ultra-high-performance tires are rated for speeds up to, but have harsher ride characteristics and durability.
- Electric vehicles have unique demands on tires due to the combination of weight, higher torque, and requirements for lower rolling resistance.
- Run-flat tires eliminates the need for a spare tire because they can be traveled on at a reduced speed in the event of a puncture, using a stiff sidewall to prevent damage to the tire rim. Vehicles without run-flat tires rely on a spare tire, which may be a compact tire, to replace a damaged tire.
- Race car tires come in three main categories, DOT, slick, and rain. Race car tires are designed to maximize cornering and acceleration friction at the expense of longevity. Racing slicks have no tread to maximize contact with the pavement and rain tires have channels to eject water to avoid hydroplaning.
Heavy duty
- Truck tires come in a variety of profiles that include "low profile" with a section height that is 70 to 45% of the tread width, "wide-base" for heavy vehicles, and a "super-single" tire that has the same total contact pressure as a dual-mounted tire combination.
- Off-road tires are used on construction vehicles, agricultural and forestry equipment, and other applications that take place on soft terrain. The category also includes machinery that travels over hardened surfaces at industrial sites, ports, and airports. Tires designed for soft terrain have a deep, wide tread to provide traction in loose dirt, mud, sand, or gravel.