| 摘要 |
PURPOSE:To reduce heel and toe wear in proportion to the amount of wear and prolong the life of a tyre by providing a side wall which is varied to have a greater angle with respect to the turning axis of the tyre when a lateral groove proceeds to wear. CONSTITUTION:In a cross-sectional view A-A' relating to a central lateral groove close to the equator of a tyre, an inclination angle beta2 with respect to the reference line L perpendicular to the tread face of the side wall at the step-in side E2 is less than an inclination angle beta1 with respect to the reference line L of the side wall at the step-out side E1. In another cross-sectional view B-B' of a central lateral groove RG1, that is taken from the view point of the tread end, an inclination angle gamma2 of the side wall at the step-in side E2 is made greater than an inclination angle gamma1 of the side wall at the step-out side E1. An angle alpha of the central lateral groove RG1 with respect the turning axis of the tyre will therefore be varied to a greater value in proportion to the amount of wear on a tread part, whereby prolonging the life of the tyre. |
