Salt is also hard on bridges and such. Some of the newer studies on studded tires have found that banning studs results in a net loss to society, due to the other measures that are needed to increase traction and to increased accident rates. Japan found that when use of studded tires dropped below some threshhold, something like 20%, road maintenance increased by a factor of 20 as everyone was actually polishing the ice on the road while the studded tire users were keeping it roughened. People in Finland who use the studless winter tires drive slower and still have a higher accident rate.