| 摘要 |
PROBLEM TO BE SOLVED: To provide a pneumatic tire having block groups demarcated by grooves and enhancing the steering stability on a dry road surface without degrading the on-ice performance. SOLUTION: A tread rubber 8 has a cap-and-base structure consisting of a cap rubber 9 located on the outer circumferential side and a base rubber 10 located on the inner circumferential side. A block group is provided at least on a part of a tread surface 7, in which a plurality of polygonal blocks 13 demarcated by linearly extending grooves, having corners more than those of a pentagon, and independent from each other are densely arranged. The block number density S per unit actual grounding area of the block group given by Formula 1 is within a range of 0.003-0.04 pieces/mm<SP>2</SP>, where P(mm) is the reference pitch length of the polygonal block in the block group, W(mm) is the width of the block group, a (pieces) is the number of blocks demarcated by the reference pitch length P and the width W and present in the reference area of the block group, and N(%) is the negative ratio in the reference area. The rubber hardness of the base rubber 10 is larger than the rubber hardness of the cap rubber. COPYRIGHT: (C)2011,JPO&INPIT |
