| 摘要 |
PURPOSE:To elongate the critical limit of a tire by making the depth of a groove at a position separating as far as a specified dimension from an equator face less than a reference groove depth denoted by dimensions in a normal direction on the equator face, and increasing the depth of a groove bottom and decreasing the sectional area of the groove toward a tread center to form a lateral groove. CONSTITUTION:At a point P separating as far as 65-100% of the half width of a tread from the equator face of a tire in a lateral groove 2, the depth Dn of a groove in the direction of a tread normal is made shallower than the reference depth DN of the groove denoted by a size in the direction of the tread normal on an equator and gradually increased from the point P toward a tread center. The sectional area AP of the groove cut by a plane containing a tread tangent and its normal at the point P is established extremely larger in comparison with the sectional area AQ of the groove cut similarly as the area AP at a position Q where the depth of the groove is the maximum, namely Dnmax, and moreover AP is gradually decreased toward the point Q. |
