Traction prediction equations for radial ply tyres

Abstract Three radial tyres (16.9R38, 18.4R38 and 24.5R32) were tested in two different soil types (Capay clay and Yolo loam), five different soil treatments (conditions) in each of the two soils, at three different axle loads and two different inflation pressures to obtain traction prediction equations for radial tyres. The field data were analysed to obtain traction prediction equations under varying soil and loading (vertical load, inflation pressure) conditions for radial ply tyres. Simulation studies were conducted to determine the effect of soil conditions, dynamic load on the axle and inflation pressure on the tractive performance of radial ply tyres. The results indicate that (i) changes in soil conditions influence tyre performance much more than changes in tyre loading and dimensions; (ii) in a given soil condition the 24.5R32 tyre appears to perform better than the other two tyres; (iii) the performance of the 18.4R38 tyre was similar to that of the 16.9R38 tyre, although at lower soil cone index values, the 18.4R38 tyre performed slightly better than the 16.9R38 tyre.