| 摘要 |
PROBLEM TO BE SOLVED: To improve partial wear resistance and crack resistance on a groove bottom, while ensuring the durability of a tread portion. SOLUTION: On the outside of second and third belt plies 7B, 7C wherein a belt cord is aligned at an angle of 10 to 45°, a fourth belt ply 7D spirally wound with the belt cord in a tire circumferential direction is provided. When the ply width of the belt plies 7B to 7D is W2 to W4 and the tread ground width is Tw, the following formulas are satisfied. 0.85Tw≤W2, W3, (W2-W3)≥14 mm, and W4≥40 mm. A distance K of an outer end of the fourth belt ply 7D from tire equator is made to be 35% to 40% of the tread ground width Tw. A reinforcing rubber layer 10 which is not less than 3.0 mm in the maximum thickness Tq and 6.0 to 12.0 MPa in complex modulus E* is arranged between the second and third belt plies 7B, 7C and at an outer end portion. COPYRIGHT: (C)2007,JPO&INPIT |
