PNEUMATIC TIRE FOR USE ON ICE-SNOW ROAD

摘要

PURPOSE:To enhance motion performance on a road of ice and snow without deteriorating dry performance by specifying a snow traction index of a tire across the whole of tread surfaces while specifying the index to such a ratio as increasing more in the center part of the tread surface than in its shoulder part. CONSTITUTION:A tread pattern of a tire is formed of a plurality of blocks 3 divided by a plurality of main grooves 1 extended in a tire peripheral direction and a plurality of subgrooves 2 crossing with these main grooves 1. A plurality of sipe 4, respectively extending in a tire width direction, are formed in each block 3. A snow traction index STI, shown by an expression I, is set to 190 to 210 in the whole of tread surfaces. Here a ratio of the snow traction index STIs of a tread shoulder part to the snow traction index STIc of a tread center part is set within a range from 0.75 to 0.90.