Winter tyres are commonly used in countries around the world that have severe winter weather conditions of snow, ice, rain and slush. The majority of large manufacturers sell rubber designed specifically for winter conditions, which are known as either winter or snow to reflect their standard times of use. A small snowflake or snow covered mountain is depicted on the tyre-wall to ensure confusion does not arise between winter and summer compounds.
Rubber designs have been created as a compound that maintains its flexibility in temperatures falling below 7C; these compare favourably with summer designs that are harder, and can become brittle in freezing winter conditions. Winter versions can be designed as narrower than regular summer wheels that cut through deep, unploughed snow; other designs include those that are wider than summer wheels that increase the amount of rubber available to grip snow covered roads. Alongside the more flexible rubber, the tread is often deeper to allow the rubber to spread across patches of snow and ice for increased grip. Braking and stopping times are often increased with a winter compound.
Many drivers believe the inclusion of electronic traction and gripping devices of their vehicles will increase the ability of the vehicle to stay on the road on snow covered roads. Although the ability of a vehicle to keep control is increased, it is not possible for a motor vehicle to stay safe on a winter road when the rubber used cannot grip the road surface. One of the main advantages of using winter compounds is the increased grip offered during dangerous driving conditions.
In some countries in Europe it is law that winter designs should be used during certain periods of the year. In other countries, such as the U.K. and U.S., a winter compound can be used throughout the year, although this is not advised by motoring organizations. Summer compounds are designed to reduce wear during regular driving conditions above 7C and reduce noise levels on motorways. A winter compound will not act as efficiently in terms of braking during summer months, and will be noisier when the vehicle is driven at high speeds.
During winter months the best option is to install a full set of snow compound rubber to increase the grip on winter roads. When a pair of tyres is installed the vehicle may be thrown out of balance and become difficult to control on snow or ice covered roads. Coupling the installation of winter tyres with winter driving techniques the safety of drivers and passengers can be increased. During snow or ice conditions drivers should double or triple their usual distance to a car ahead; braking should be limited to emergency situations, with speeds kept to a sensible level.