This study has measured road grip on wet, salted asphalt road at freezing temperatures for used and new winter tyres, with the purpose to investigate how the road grip for the three different types of winter tyres that exist in Sweden degrade by age and degree of wear. Also summer tyres were included in the study.
In total, 84 tyres have been tested, of which 31 were completely new while 53 were used. The tyres have been tested on smooth ice and packed snow.
The results show that studded tyres and un-studded Nordic winter tyres have the same are road grip on the tested road surface. The difference between new and worn tyres for these two tyre types are for most of the investigated performance measures negligible. The new European winter tyres perform 10–13 per cent better than the two other types of winter tyres on wet asphalt in the current weather conditions. For the worn tyres, the advantage of the European tyres is smaller, 5–7 per cent better than the other two types of winter tyres. The summer tyres perform as good as, or better, than the European winter tyres. This applies to both new and worn tyres.