Snow tires have more sipes than summer tires, increasing traction on snow and ice, but reducing grip on dry and wet roads. Tires designed for winter conditions are optimized to drive at temperatures below 7°C (ca 46 Fahrenheit).
In much of Scandinavia, snow tires may have metal studs to improve grip on packed snow or ice, but such tires are prohibited in most other countries because of the damage they cause to the road surface. The metal studs are fabricated by encapsulating a hard pin in a softer material. The pin is often made of tungsten (wolfram) carbide, (hard metal). 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 stick out of the tire. The pin should stick out 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.
Regional symbols and rules
In the United States and Canada, a "3PMSF ("Three Peak Mountain Snow Flake")" symbol means that the tire has exceeded the industry requirement from a reference (non-snow) tire.
In Europe, requirements for snow tires vary by country: in the Czech republic, Estonia, Finland, Germany, Lithuania, Latvia, Norway, Romania, Slovenia, Austria,Luxembourg and Sweden, the use of snow tires is a legal requirement during winter months (usually November to mid-April) or if snow or slush is present on road surfaces; failure to comply can result in on-the-spot fines from the police. Andorra, Italy and Switzerland all recommend snow tires but they are not a requirement.
Since July 2008, the Czech Republic uses the Europe-wide road sign requiring the use of snow tires in marked mountainous areas during winter. The duration of obligatory snow tire use was originally November – April (Ordinance 208/2008 Sb.). This was later changed to November – March (Ord. 91/2009 Sb.).
- "The Benefits of Winter Tires". thoughtsbypilvi.com. Retrieved 2012-10-24.
- ScienceDaily (6 January 2011). "How Studded Winter Tires May Damage Public Health, as Well as Pavement". Retrieved 26 January 2011.
- Nordström, Olle (2004). VTI Meddelande 965 - 2004 (Report).
- Gustafsson, M., et al. (2006). VTI rapport 543 - Effekter av vinterdäck - en kunskapsöversikt (Report).
- "Winterausrüstungspflicht - was gilt?". ÖAMTC. Retrieved 22 January 2013.
- "Winter tyres mandatory in Luxembourg" Rezulteo tyres, Retrieved 6 February 2013
- "Driving to Europe in winter". The Automobile Association. Retrieved 16 January 2013.
- "Winterreifenpflicht bei Glatteis, Schneeglätte, Schneematsch, Eis- oder Reifglätte". Bayerische Polizei. Retrieved 16 January 2013.
- "Winter tire and snow chain requirements". UK: The Automobile Association. Retrieved 11 December 2010.[dead link]