Patent ID: 7270161
Filing Date: 2007-09-18
Classification: B60C

Abstract:
1. A pneumatic tire for a motorcycle, comprising: a tread which has a tread surface portion whose external surface curvature is comparatively large; a pair of zigzag circumferential direction grooves for defining a central continuous circumferential rib which is positioned at a central portion in a tire axial direction of the tread and which extends in a zigzag shape continuously in a tire circumferential direction, which extend in a zigzag shape along the tire circumferential direction; and a plurality of pairs of inclining grooves, the inclining grooves being provided in the tire circumferential direction so as to be separated from each other at an interval at both sides in a tire transverse direction of the pair of zigzag circumferential direction grooves and being inclined with respect to the tire transverse direction such that each inclining groove extends from a tread end toward a tire equatorial plane and terminates near the zigzag circumferential direction groove without contacting therewith, and an end portion of the inclining groove at a tire equatorial plane side is positioned further to a tire rotational direction side, than an end portion of the inclining groove at a tread end side, characterized in that the inclining groove has a sharp inclining groove portion which is positioned at the tire equatorial plane side, and whose angle with respect to the tire circumferential direction is within a range of 0 to 20 degrees, and a loose inclining groove portion which is positioned at an external side in the tire transverse direction of the sharp inclining groove portion and whose angle with respect to a tire circumferential direction is set larger than the angle of the sharp inclining groove portion, a first longitudinal land portion having a substantially uniform width and a second longitudinal land portion having a width which gradually increases in a direction opposite to the tire rotational direction are alternately connected to each other and arranged in the tire circumferential direction between sides forming a zigzag shape of the zigzag circumferential direction groove and the sharp inclining groove portions, due to that a main portion of the sharp inclining groove portion at the tire equatorial plane side is positioned so as to face the side forming a zigzag shape of the zigzag circumferential direction groove, and portions of one sharp inclining groove portion and another sharp inclining groove portion of the inclining grooves adjacent to each other in the tire circumferential direction are made to overlap one another in the tire transverse direction.