| 摘要 |
PURPOSE:To improve the safety in traveling by maintaining the grip performance and brake application performance for the traveling on a slippery ice snow road surface. CONSTITUTION:As for a groove sectional shape in the perpendicular direction for a lateal groove 4 on the lateral groove 4 which extends in the direction crossing with the tire circumferential direction on a tread surface and at least one end is opened at the tread edge or in the circumferential direction groove, the distance D2 which is larger than 1/2 times of the groove depth D of the lateral groove and smaller than 3/4 times is divided to the groove upper region 5 outside in the radial direction from a division pakt P separated inward in the radial direction from the tread surface and a groove lower region 6 inside. Accordingly, the groove wall surface 7 in the groove upper region consists of the redius R larger than the distance D2 and smaller than 1.5 times of the groove depth D1, and formed from an arcuate surface which bulges in a projection form toward the groove, and the groove width W2 at the division point P is larger than 1/3 times of the groove width W1 on the tread surface of the lareral groove and smaller than 1/2 times. |
