The method determines both friction and wear resistance of tread compounds. Part I deals with wet traction. Surface structure, temperature and sliding speed determine the friction coefficient of a tread compound. Using the WLF trans form, mastercurves are obtained demonstrating that the log a(T)v-value in the contact area determines the friction properties. if temperature and sliding speed are adjusted to correspond to the log a(T)v-value in a tire test high correlations are obtained between spot laboratory and road test. Because the structure of the sliding surface influence the shape of the master curve, two laboratory surface of different roughness may be necessary to characterise a road surface. A double correlation weights the contribution of the two surfaces.