Tire, Pneumatic
The pneumatic tire was invented in 1845 by the Scotsman Robert Thomson. Vehicles of that time had wooden wheels with steel tires, which wore well but produced a jolting, vibrating ride were subject to skidding. Thomson designed a great improvement, a non-stretchable cover over a rubber inner tube pumped up with air. Although Thomson's " Aerial Wheels" did give a much smoother ride, they attracted little interest and were soon forgotten.
Solid rubber tires began replacing steel tires in 1870 in England, but they didn't solve the vibration problem. As the bicycle craze grew in the 1880s, the need to improve the ride of these "boneshakers" became more pressing. A Scottish veterinarian practicing in Ireland, John Boyd Dunlop, found the solution for his son's tricycle. He put together a rubber tube with a one-way valve for inflating, covered it with a rubber casing, and attached it to the trike's rear wheels with wrappings of tape. Dunlop patented his new pneumatic tire in 1888, unaware of Thomson's similar patent design of 1845.
These fat "mummy" tires were ridiculed at first, but they rapidly gained favor with racing cyclists, who appreciated both the smoother ride and the easier pedaling pneumatics produced. Dunlop-type tires soon became standard for bicycles. In 1890 Charles K. Welch of Tottenham patented an improved method of fastening the tire to the rim using wire embedded in the casing, and William Erskine Bartlett, an American expatriate living in England, invented the bead on the edge of the casing. The French brothers, Edouard and André Michelin, introduced the removable pneumatic tire in 1891, which allowed the driver rather than a mechanic to fix a blowout quickly and efficiently.
The greatest application and importance of the pneumatic tire was for something Dunlop had not envisioned. It made possible the automobile age--cars couldn't run successfully without pneumatic tires. The Michelins surprised competitors by using pneumatics on an automobile for the first time in 1895, in the great Paris to Bordeaux race. Later that year pneumatics made their first appearance on an American car in the Chicago-Evanston race. The United States tire industry soon established itself at Akron, Ohio: Benjamin F. Goodrich (1841-1888) had moved there in 1870 and made its first pneumatic tires in 1896; Goodyear Tire Company was incorporated there in 1898; Harvey Firestone (1868-1938) started tire manufacturing in Akron in 1903.
Two-part high-pressure pneumatic tires appeared in the early 1900s, being a casing with a flexible rubber inner tube inside. Low-pressure balloon tires were introduced in 1922, pioneered by Firestone. The tubeless tire with an airtight casing came in 1948 and by the mid-1950s became the industry standard. Recently, tires have been developed that seal themselves and can continue to run when punctured.
For many years, bias-ply tires were the standard type of pneumatic tire. In a bias-ply tire, fabric cords in the inner lining of the tire are laid at angles to the wheel axle and run in layers over each other. In radial-ply tires, the cords run from one bead to another, parallel to the axle. Conventional bias-ply tires have fabric cords; belted bias-ply tires have fiberglass belts that circle the tire, over the cords; belted radial-ply tires have steel mesh belts. A belted radial ply tire design was patented in 1914 by Christain H. Gray and Thomas Sloper of England, but the tire was not marketed. The Michelin company applied for the patent on today's modern radial-ply belted tire in 1946; the tires themselves went into production early in 1948. They soon became standard in Europe, but were not commonly used in the United States until the 1970s.
Radial tires proved to give roughly 20 % less rolling resistance (or friction) than bias-ply tires, and therefore provided a significant reduction in fuel consumption. In the United States from 1970 to 1992, radial tires were responsible for saving approximately 77 billion gallons of gasoline. Once radials were generally adopted, tire engineers in the 1980s concentrated on further decreasing their rolling resistance by eliminating any excess mass in the shape of the tire itself. Tires of the 1980s thus had a slimmer look that replaced the wide-shouldered "macho" tires of the 1970s. In the 1990s, engineers concentrated on increasing a tire's efficiency, and eventually turned their attention to composite materials.
Tires have long been made out of a combination of many different natural and synthetic materials, one of which is called carbon black. This necessary oil by-product stiffens or hardens a tire's tread, but it also creates unnecessarily high friction. In the late 1980s, engineers began experimenting with different materials and tried silica -- the basic component of ordinary beach sand -- to replace carbon black. It was found to reduce friction remarkably well. Eventually, once the problems of lower durability, decreased traction in wet weather, high cost, and complicated manufacture were solved by the Michelin tire company, it began to produce a new silica-blend tire by the end of the 1990s. These new tires reduce friction with no sacrifice of any other factor, and are only slightly more expensive. It is estimated that once America converts to silica-blend tires, 2.4 billion gallons of fuel will be saved each year, with a related reduction of carbon dioxide emissions.
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