| 摘要 |
PROBLEM TO BE SOLVED: To suppress both of river wear and heal and toe abrasion and to prevent biting of a stone in the circumference groove by arranging a projection with an appropriate dimension in the groove bottom of the circumference groove and properly forming a tread face shape in a block land part. SOLUTION: A plurality of circumference grooves 2 and lateral grooves 3 are arranged in a tread 1, and by means of these grooves, multiple sectioned block land parts 4a, 4b, 4c are formed, while a low part, 8 is provided in the proper position in each of the block land parts 4a, 4b, 4c, and a projection 9 is arranged in the groove bottom of the circumference groove 2. A length between a tread opening end (a) position in the circumference groove 2 and a width end position (c) of the tread opening end (a) position side on a projection upper face 10 and a length between a tread opening end (b) position in the circumference groove 2 and a width position (d) of the tread opening end (b) position side on the projection upper face 10 are projected on a straight line along the tire diameter direction and on a straight line along the tire width direction, and distances D1 , D2 are provided by measurement of the projected lengths on the straight line along the tire diameter direction, while distances W1 , W2 are provided by measurement of the projected length on the straight line along the tire width direction. The distances D1 , D2 , W1 , W2 satisfy the following relationship: D1 >0.5×W1 , D2 >0.5×W2 . |
