This study is part of an investigation concerning the possibilities of reducing road wear caused by studded tyres. The study evaluates the differences in driving characteristics between winter tyres with studs and non-studded winter tyres of friction tyre type. It was carried out in traffic in Stockholm by means of subjective rating by taxi drivers. The time period was from November 1, 1988 to April 1, 1989. As an objective reference, tyre data concerning stud protrusion, static stud force and friction on ice were measured on some of the tyres used in the study. The drivers were of the opinion that studded tyres were needed on icy roads during 26% of their driving periods. For the rest of the time the friction tyres were considered as equally good. It was noted that the friction tyres were less noisy than the studded tyres. The stud protrusion was about 1 mm at the start and between 0,5 and 0,7 mm at the end to the test period. During severe ice conditions the measured friction was about twice as high for the new studded tyres as for the friction tires. Worn studded tyres with about 0,6 mm stud protrusion had the about the same friction as non-studded tyres. (A)
Abstract