Tire Seasons
Most cars sold in the UK are factory fitted with summer tires. These tires are designed to work in all conditions, however they're optimised for warmer temperates. When the temperature drops outside of the optimum zone the rubber hardens up offering reduced grip in both dry and wet conditions.Winter tires, also known as cold weather tires are designed to work in cooler, sub 7c conditions. These are a legal requirement in certain countries and offer far superior handling and grip in winter conditions.
All season tires are designed to be used year round. They're neither optimum for summer or winter, they do however offer reasonable performance in all conditions without the draw backs of summer tires in the cold, or winter tires in warm conditions.