Passenger car tyres come in three types: summer, winter and all-season. The tread can be symmetric, asymmetric or directional. Summer tyres can be used from spring till autumn, when temperatures are higher than 7°C. Lower temperatures reduce the effectiveness of the tyres' properties, making it worth fitting winter tyres in the colder months. Winter tyres have a rubber compound and tread which are designed to drive in winter conditions. Winter tyres have more grooves and lamelles, which provide better traction on snow. Summer tyres use all possible tread patterns; however, in winter tyres only two are used: asymmetric and directional. All-season tyres have some of the features of both winter and summer tyres. These tyres are usable all year round, regardless of weather conditions. All-season tyres are recommended for drivers with a calm driving style, who drive over 6,000 km a year. Summer tyres are suitable for drivers who clock 5-6,000 km a year with a dynamic or aggressive driving style. Tyre manufactures aim to produce tyres which have excellent grip on both wet and dry surfaces, short braking distance, fuel economy and high comfort. The real challenge is to design winter tyres which have a good grip on snow, slush and wet surfaces while not generating excessive noise.