Abstract
The effect of studded tyres on traffic accidents is investigated. The investigation covers the whole of Sweden and is based upon 24000 accidents and 202000 inquiries concerning the previous day’s driving distance. Given the weather conditions the direct effect of studded tyres is 0.72 according to the gross method and 0.86 according to the net method. Under these conditions, when the mean frequency of studs was 51%, the prohibition of studs would have caused the number of accidents to increase by between 7 and 17%.