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Snow tires - often also called winter tires - are tires designed for use in colder weather, snow and ice. Snow chains can be a slower-speed, temporary alternative in snowy conditions. Snow tires have more sipes than summer tires, increasing traction on snow and ice. Tires designed for winter conditions are optimized to drive at temperatures below . Studded tires with metal pins that protrude from the tire can greatly reduce skidding and accidents on snow or ice-covered roads. However, the metal studs make contact to the road pavement which eventually cut into the pavement allowing water to get in. The water can cause road damage and create hydroplaning hazard. ==Studded tires== In much of Scandinavia, Canada, and the US, snow tires may have metal studs to improve grip on packed snow or ice, but such tires are prohibited in certain other jurisdictions because of the damage they cause to the road surface. The metal studs are fabricated by encapsulating a hard pin in a softer material base, sometimes called the ''jacket''. The pin is often made of tungsten carbide, a very hard high performance ceramic. The softer base is the part that anchors the stud in the rubber of the tire. As the tire wears with use, the softer base wears so that its surface is at about the same level as the rubber, whereas the hard pin wears so that it continues to protrude from the tire. The pin should protrude at least 1 mm for the tire to function properly. Snow tires do not eliminate skidding on ice and snow, but they greatly reduce risks. Studdable tires are manufactured with molded holes on the rubber tire tread. Typically, there are 80 to 100 mole holes per tire for stud insertion. The insertion is done by using a special tool that spreads the rubber hole so that a stud jacket can be inserted and the flange at the bottom of the jacket can be fitted nicely to the bottom of the hole. The metal studs come in specific heights to match the depths of the holes molded into the tire tread based on the tread depths. For this reason, stud metals can only be inserted when the tires have not been driven on. A proper stud insertion results in the metal jacket that is flush with the surface of the tire tread having only the pin part that protrudes out.〔(【引用サイトリンク】url=http://www.tirerack.com/winter/tech/techpage.jsp?techid=151 )〕 There is a new development of tires with retractable studs. The concept is to allow the pin part of the stud to be able retractable based on the activation and deactivation with a press of a button by the driver. 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「Snow tire」の詳細全文を読む スポンサード リンク
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