Estimating the traffic safety effect of studded tires.

Swedish accident and exposure data from December 1989 to February 1990 are used to estimate the risk of involvement in an accident on a slippery road when using studded tires compared with the risk when driving with summer tires. Two methods have been used, one involving both accident and exposure data, the other using only accident data. Both methods give similar estimates, indicating that studded tires reduce the risk of involvement in slippery road accidents by 20%-50%.