In short winter tyres will improve traction, grip and braking in slippery conditions. They are designed to work better than summer tyres in temperatures below 7°C also their special tread pattern means they will perform better in the wet reducing aquaplaning as their extra-deep tread help the tyre disperse more surface water. In the UK there is always a gamble on this investment as our winters can be quite mild, on the other hand, if we have a hard winter they are worth every penny. Although, once temperatures rise above 7°C performance can be significantly weaker. You will experience increased braking distances, and less grip on bends increased road noise and increased wear rates, so make sure once the weather has improved towards spring you exchange the winter tyres for summer tyres.