| 摘要 |
PROBLEM TO BE SOLVED: To significantly improve performance on ice and snow by achieving an appropriate tread pattern. SOLUTION: A block group G<SB>B</SB>formed by mutually and densely arranging a plurality of independent blocks 3 is provided at part of a tread part 1. When a reference pitch length of each block 3 in the block group G<SB>B</SB>is set as P (mm), the width of the block group G<SB>B</SB>as W (mm), the number of the blocks 3 existing in a reference zone Z, partitioned by the reference pitch length P and the width W, of the block group G<SB>B</SB>as a (piece), and the negative rate in the reference zone Z as N(%), a block-number density S per unit actual grounding area of the block group G<SB>B</SB>given by a/(P×W×(1-N/100)) is within the range of 0.003 to 0.04 pieces/mm<SP>2</SP>. Each block 3 is formed into a quadrangle whose each angle is all 45 degrees or more. Each block 3 is formed to have the same size. All of the four sides constituting the surface contour of each block 3 is inclined with respect to both of the tread circumferential direction and the tread width direction. COPYRIGHT: (C)2010,JPO&INPIT |
