| 摘要 |
PURPOSE:To obtain a tire of excellent running performance further with a less damage trouble during manufacture, by using tread rubber with tear strength 18kg/cm or less at 170 deg.C. CONSTITUTION:If an angle alpha formed by a side wall 3 of a groove 2 and a plane 4 of the grounded part in a tread 1 is smaller than 92 deg., a catch of rubber is generated at mold releasing to cause demold splitting, while if reversely the anglc is larger than 135 deg., drainage is worsened to decrease brake performance and driving stability on a wet surface road, and the angle alpha is formed to a degree above 92 deg. and below 135 deg.. While for a radius of curvature R in the connection part between a groove bottom part 5 and the wall 3 not larger than 2mm., the demold splitting is easily caused, on the contrary for the radius not smaller than 5mm., a curved surface is discontinuously formed to easily generate a groove bottom crack by concentration of stress at running time, and the radius of curvature is set above 2mm. and below 5mm.. |
