Nya och begagnade vinterdäcks isfriktion [Elektronisk resurs] sammanfattningsrapport. undersökning avseende inverkan av ålder, mönsterdjup, slitbanehårdhet, dubbutstick och dubbkraft

• It has been argued that the grip of winter tyres on ice and snow deteriorates with age to such an extent that winter tyres above a certain age e. g 10 years should be forbidden to use. Little research data do however exist. This investigation has been carried out by VTI in order to get a better background for legal decisions. The results would also be of use for ordinary consumers as a guidance. It comprises three part studies on different surfaces, wet ice, smooth ice -3ºC and rough ice -3ºC. The aim of the investigation is to investigate the correlation between ice grip of winter tyres and their age, tread depth and tread rubber hardness and for studded tyres also stud protrusion and stud force. The investigation comprises 20-23 studded and 33-43 non studded winter tyres and four summer tyres mainly of the in Sweden popular brands Gislaved, Michelin and Good Year of size 185/65-15, 195/65/-15, 185/70-14, 165-15. All were radial tyres manufactured between 1981 and 2003. Most of the tyres had been driven in ordinary traffic. A small number of new winter tyres were also tested. As reference some new summer tyres were tested as well. The steering and braking performance of the tyres has been measured in a special climate controlled indoor high speed flat bed test facility developed by the VTI. Very good correlation has earlier been found between results from the facility and lap time results from ice track circuit tests with cars as well as pure braking and cornering tests with cars on ice tracks. The new winter tyres were clearly better than the average of the older tyres. In the age range 5 to 15 years however no significant influence of age on the ice friction of winter tyres could be found regardless of if they were studded or not. The results also show that on this surface studded tyres as a group still are superior to non studded tyres including the specialised studless winter tyres often called "friction tyres". The differences in friction are largest on wet ice and smallest on rough ice. The test results from this investigation do not answer the question whether or how the performance of a stored unused tyre is reduced with time. Results from an earlier investigation by VTI showed no deterioration within three years of storage. 

Ämnesord

Road: Components of the vehicle  (vti)

Road: Components of the vehicle  (vti)

Indexterm och SAB-rubrik

Swedish

Sweden

Studded tyre

Icy road

Wet road

Friction

Deterioration

Age

Depth

Winter

Rubber