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Motorcycle tyres (tires in American English) are the outer part of motorcycle wheels, attached to the rims, providing traction, resisting wear, absorbing surface irregularities, and allowing the motorcycle to turn via countersteering. The two tyres' contact patches are the motorcycle's connection to the ground, and so are fundamental to the motorcycle's suspension behaviour, and critically affect safety, braking, fuel economy, noise, and rider comfort.〔〔 ==History== The history of motorcycle tyres is a clear progression of steady improvement in grip, allowing better acceleration, braking, and turning, along with improved comfort, safety, durability, and reliability. This progression has generally meant a steady increase in tyre width, so much so that Kevin Cameron noted the assumption among riders that "bigger must be better in every way", leading to, "the temptation to overwhelm motorcycles with the biggest tyres the owner can find."〔 While many advances in tyre materials and construction have yielded unalloyed benefits, at a given level of technological sophistication, every design choice, such as tyre width, diameter, cross-section curvature, and the geometry of the motorcycle the tyres are intended for is a trade-off and a compromise.〔 Pneumatic tyres were invented by John Boyd Dunlop in 1888, and were in widespread use on bicycles and some early motorcycle prototypes by 1895.〔 They were used on the first production motorcycle, the 1894–1897 Hildebrand & Wolfmüller, and have been on nearly all production and special motorcycles ever since.〔〔 During this period tyre sizes were usually diameter and wide.〔 The early wheels were spoked, made of all metal, or wood and metal, and used inner tubes to hold air.〔 Flats were a constant problem; largely the fault of poor roads and not necessarily tyres.〔 For easier repair, butt-ended or open ended inner tubes were used on some models, and some brands made rear wheels easier to detach.〔 Spoked wheels with tubes remained standard until the 1970s, when solid, usually alloy, wheels began to appear and eventually dominate street motorcycles, making lighter tubeless tyres practical. As the early motorcycle industry progressed, larger tyre sizes accompanied larger engine displacements, so that by 1909–1914, section, diameter tyres were used on motorcycles, and section tyres appeared on motorcycles with displacements over 350 cc.〔 Indian tyres reached , giving even greater rider comfort but with a taller seat height.〔 From 1915 to 1929, tyre quality continued to increase, and beaded edge tyres began to be replaced by wired-on beads, which used steel loops embedded in the tyre's edge to prevent it from expanding under pressure, so the bead no longer needed a grooved rim to hold it in place.〔 Banded-edge tyre were obsolete and replaced entirely by the wired-on type by 1930.〔 In the period 1956–1964, typical tyre grip increased by 40%, resulting in better cornering, shorter stopping distance and overall improved safety.〔 This was the result of a greater range of tyre sizes appearing on the market, from small scooter tyres through heavyweight motorcycle tyres. A variety of rubber compounds and tread patterns further expanded the options, specialized for wet roads, smooth dry roads, racing, off-road use, and sidecars.〔 Both natural and synthetic rubber were used, and tyres included fibres of cotton, nylon, and rayon for various structural benefits.〔 During the 1970s, the increasing widths of tyres led to major changes in road racing cornering technique, leading to riders ''hanging off'' or ''knee dragging'', in which the rider moves their body far off centre for the purpose of changing the combined centre of gravity of the rider plus bike, in order to turn at a given radius and speed at less of a lean angle.〔 Racer John Surtees had been hanging off his MV Agusta as far back as the 1950s, in spite of resistance to the practice at that time from other riders, saying, "The idea is to keep the machine as upright as possible for maximum traction." Tyres of the 1960s and early 1970s had a rounder profile, but as they grew in width from the mid-1970s, the cross section became more oval, and the greater width of the tyre meant the contact patch was further off centre, increasing either steering effort or turn radius, at a given lean angle and speed, than it would have been with a rounder profile.〔 To compensate, riders leaned out, moving their body's centre of gravity away from the motorcycle, eventually leaning out so far that their knee would skid along the pavement.〔 Ablative ''knee pucks'' or ''knee sliders'' were then added to the riders' racing leathers to allow their knees to scrape smoothly along the tarmac through turns.〔 The first radial tyres for cars appeared in 1943,〔 but motorcyclists waited forty more years for this technology to come to motorcycles. These were the 1983 Pirelli MP7 radials, introduced on the European version of the 1984 Honda VF1000R, a limited edition exotic motorcycle that showcased a number of new technologies including carbon fibre reinforced bodywork and air-adjustable anti-dive front forks.〔〔 The new radial tyres had to provide race-replica handling for the very heavy dry weight chassis, up to a top speed of , making it the fastest production motorcycle of its day.〔 The MP7 radials came to the US market in 1985.〔 Radial construction uses textile or steel belts arranged at 90 degrees to the direction of travel, along with a layer of belts running around the tyre's circumference, with motorcycle radials deviating from the true radial design by adding belts running at angles to the radial belts, in the manner of bias-ply tyres, allowing the grip, durability, feel, and other characteristics to be adjusted to suit the tyre's design.〔 The benefit of radial tyres is that the tyres run cooler yet maintain great flexibility, allowing engineers to coax significant increases in both grip and tread life, without compromise, under a broader range of conditions than bias-ply tyres.〔 Changing tyre technology continued to influence riding style in 2013 in MotoGP, when rider Marc Márquez adjusted the knee-down cornering style begun by Mike Hailwood to a more extreme knee-and-elbow down turning, with much of his upper body off center. Márquez was working to use to best advantage the characteristics of the spec Bridgestone tyres all teams had been assigned since 2011, moving off center to keep the bike as upright as possible in the corner apex, and off the relatively flexible edge of tread area.〔 To keep pace, other riders had to learn this physically demanding maneuver, requiring practice to change body position smoothly without upsetting the bike, a properly set up suspension keyed for this style of riding, and targeted muscle development to hold body position.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Motorcycle tyre」の詳細全文を読む スポンサード リンク
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