Patent ID: 7527082
Filing Date: 2009-05-05
Classification: B60C

Abstract:
1. A pneumatic tire in which at least a pair of circumferential grooves extending continuously along the tire circumferential direction are disposed at a tread portion, an inner land portion and an outer land portion are defined by disposition of the outermost circumferential grooves, which are the circumferential grooves located at the outermost in the tire width direction among these circumferential grooves, a plurality of transverse grooves extending with inclination with respect to the tire circumferential direction are disposed on at least the outer land portion and the outer land portion is divided and formed into a large number of blocks by these transverse grooves, said tire being characterized in that the outermost circumferential groove has its both opening end edges extending along the tire circumferential direction, the width of the groove bottom is narrower than the opening width, the groove bottom extends between adjacent transverse grooves disposed on the outer land portion with inclination with respect to the tire circumferential direction so that it substantially continues to one of the transverse grooves of the adjacent transverse grooves, the groove bottom forms the zigzag shape as a whole and a chamfered part is provided on both groove walls of the outer groove walls disposed on the blocks between the transverse grooves and the inner groove walls opposing to the outer groove walls which is inclined with a certain angle from the opening end edge toward the groove bottom, respectively and whose chamfered width is gradually increased in the opposing orientations in the circumferential direction; wherein, the groove bottom which forms the zigzag shape has a substantially uniform bottom width along its length; and wherein the groove including the groove bottom has a first portion of substantially uniform width extending upwardly from the groove bottom and a second portion which is above the first portion and in which the width of the groove gradually increases; and wherein the chamfered surface of the inner and the outer chamfered parts have a flat plane in an inverted triangle shape.