Hydroplaning becomes more prevalent with wider tires

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Hydroplaning becomes more prevalent with wider tires (because of the lower weight per contact area) and especially at higher speeds; it is of virtually no concern to bicycle tires under normal riding conditions largely because of the lower speeds. The chance of car hydroplaning is also minimal at bicycle speeds as the weight per contact area of car tires is not much lower if any than bicycle tires.
25/12/2015 Tire ­ Wikipedia, the free encyclopedia 26/32 Tire showing weather­cracking over long­term exposure to the weather. A child plays in a playground made from recycled tires. Guelph, Ontario Dangers of aged tires Research and tests show that as tires age, they begin to dry out and become potentially dangerous, even if unused. Aged tires may appear to have similar properties to newly manufactured tires, but rubber degrades over time, and once the vehicle is traveling at high speeds (i.e. on a freeway) the tread could peel off, leading to severe loss of control. In tropical climates, tires degrade sooner than in temperate climates, and more care should be taken in these climates to ensure that tires do not fail. Also, tires on seldom­used trailers are at the greatest risk of age­failure, but some tires are built to withstand idleness, usually with nylon reinforcement. Many automakers recommend replacing tires after six years, and several tire manufacturers (Bridgestone, Michelin) have called for tires to be removed from service 10 years after the date of manufacture. However, an investigative report by Brian Ross on ABC's 20/20 news magazine found that many major retailers such as Goodyear, Wal­Mart, and Sears were selling tires that had been produced six or more years ago. Currently, no law for aged tires exists in the United States. [66][67] Scrap tires and environmental issues Once tires are discarded, they are considered scrap tires . Scrap tires are often re­used for things from bumper car barriers to weights to hold down tarps. Some facilities are permitted to recycle scrap tires through chipping, and processing into new products, or selling the material to licensed power plants for fuel. Some tires may also be retreaded for re­use. One group did "a study to evaluate the possibility of using scrap tires as a crash cushion system. The objective of this study was to evaluate the material properties of used tires and recycled tire­derived materials for use in low­cost, reusable crash cushions". [68] An interesting use, developed over 30 years back but not yet universally used, is to process scrap tires as raw material for roads. The process is removing the metal, granulating the rubber and then a chemical process where it is mixed with other usual materials for macadamised roads. The resulting roads have proved to have better waterproofing, more resilent resulting in a smoother ride and also longer tire life. Several countries (for example, South Korea) have regulations requiring its use, but most do not.

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