What is "snow chains"

n. (snow chain English)

n. chains attached to wheels to increase traction on ice or snow [syn: tire chains]

Snow chains, or tire chains, are devices fitted to the tires of vehicles to provide maximum traction when driving through snow and ice.

Snow chains attach to the drive wheels of a vehicle or special systems deploy chains which swing under the tires automatically. Although named after steel chain, snow chains may be made of other materials and in a variety of patterns and strengths. Chains are usually sold in pairs and must be purchased to match a particular tire size (tire diameter and tread width). Driving with chains reduces fuel efficiency, and can reduce the allowable speed of the automobile to approximately 50 km/h (30 mph), but increase traction and braking. Some regions require chains to be used under some weather conditions but some areas prohibit the use of chains which can deteriorate road surfaces.