Alloy wheels are wheels that are made from an alloy of aluminium or magnesium. Alloys are mixtures of a metal and other elements. They generally provide greater strength over pure metals, which are usually much softer and more ductile. Alloys of aluminium or magnesium are typically lighter for the same strength, provide better heat conduction, and often produce improved cosmetic appearance over steel wheels. Although steel, the most common material used in wheel production, is an alloy of iron and carbon, the term "alloy wheel" is usually reserved for wheels made from nonferrous alloys. The earliest light-alloy wheels were made of magnesium alloys. Although they lost favor on common vehicles, they remained popular through the 1960s, albeit in very limited numbers. In the mid-to-late 1960s, aluminum-casting refinements allowed the manufacture of safer wheels that were not as brittle. Until this time, most aluminum wheels suffered from low ductility, usually ranging from 2-3% elongation. Because light-alloy wheels at the time that were often made of magnesium (often referred to as "mags"), these early wheel failures were later attributed to magnesium's low ductility, when in many instances these wheels were poorly cast aluminum alloy wheels. Once these aluminum casting improvements were more widely adopted, the aluminum wheel took the place of magnesium as low cost, high-performance wheels for motorsports. Tubeless tires or tyres (in some Commonwealth Nations) are pneumatic tires that do not require a separate inner tube. Unlike pneumatic tires which use a separate inner tube, tubeless tires have continuous ribs molded integrally into the bead of the tire so that they are forced by the pressure of the air inside the tire to seal with the flanges of the metal rim of the wheel. Contents 1 History 2 Safety 3 Tire sealants 4 Bicycle tires 4.1 UST 4.2 Road tubeless 5 See also 6 References 7 External links History Many patents had been filed covering tubeless tires. Killen Tire applied for a patent in 1928 and was granted GB patent 329955 in the UK in 1930. The Wingfoot Corporation, a subsidiary of Goodyear Tire were granted a patent in South Africa in 1944. Due to technical problems, most of these designs only saw limited production or were abandoned. Frank Herzegh working for BF Goodrich applied for a patent in 1946 and eventually received US patent 2587470 in 1952 in the United States. By 1955 tubeless tires became standard equipment on new cars.[1] BF Goodrich had to defend their patent in court several times, due to the similarities of previous designs. The primary difference between the BF Goodrich design and their predecessors was the usage of butyl rubber, which was more resistant to air leakage than the natural rubber used in the other designs.[2][3] Safety Traditional designs of pneumatic tires required a separate inner tube which could fail for a number of reasons, such as incorrect tire fit, friction between the tire wall and inner tube generating excess heat, or a puncture. Tubeless tire technology does away with the need for an inner tube thereby increasing safety.[1][4][citation needed] In a tubeless tire, the tire and the rim of the wheel form an airtight seal, with the valve being directly mounted on the rim. If a tubeless tire gets a small puncture, air escapes only through the hole, leading to a gentle deflation. Conversely, an inner tube could potentially burst like a balloon, leading to deflation of the tire which could result in sudden loss of control of the vehicle. However, the "bursting like a balloon" scenario is highly unlikely due to fact that the inner tube is inside of the tire and will deflate at a rate proportional to the puncture hole size. Tire sealants Liquid tire sealant can be injected into tubeless tires to prevent deflation in case of small punctures, although there is controversy regarding its compatibility with direct tire pressure monitoring systems (TPMS) that employ sensors mounted inside the tire. Some manufacturers of sealants assert that their products are indeed compatible,[5] but others warned that, e.g., the "sealant may come in contact with the sensor in a way that renders the sensor TEMPORARILY inoperable until it is properly cleaned, inspected and re-installed by a tyre care professional".[6] Such doubts are also reported by others.[7][8] Use of such sealants may void the TPMS sensor warranty.[5]

• published: 29 Dec 2016
• views: 511