Patent ID: 8578985

Claim:
A pneumatic tire comprising a tread portion having a plurality of circumferential main grooves extending continuously in a circumferential direction of the tire, a plurality of lateral grooves extending in a direction intersecting said circumferential main grooves to divide said tread portion into a plurality of blocks, and sipes having a zigzag part and provided in said blocks, and a pair of shoulder portions each including a tread ground contact edge of the tread portion and having a round shoulder shape such that a profile line in the meridian section of the tire comprises a circular arc curve having a radius of curvature of at least 25 mm, said plurality of circumferential main grooves including a pair of axially outermost circumferential grooves dividing said tread portion into shoulder regions located axially outward of said outermost circumferential grooves and a crown region located between said outermost circumferential grooves, wherein said zigzag part of each of said sipes disposed in said shoulder regions has an amplitude Wsh and a pitch Psh and said zigzag part of each of said sipes disposed in said crown region has an amplitude Wcr and a pitch Pcr which are smaller than said amplitude Wsh and said pitch Psh, respectively, said sipes disposed in said shoulder regions are inclined at an angle θsh with respect to an axial direction of the tire and said sipes disposed in said crown region are inclined at an angle θcr with respect to the axial direction which is larger than said angle θsh, and in each said shoulder region, the lateral grooves disposed therein are inclined to one direction with respect to the axial direction and a zigzag center line of the zigzag part of each said sipe disposed therein is inclined with respect to the axial direction to the same direction as the inclination direction of the lateral grooves, wherein the zigzag part has a sawtooth form formed by alternately arranged first zigzag sides and second zigzag sides, the first zigzag sides intersect with said zigzag center line at a larger angle α and are inclined with respect to the axial direction to a direction opposite to the inclination direction of said zigzag center line with respect to the axial direction, and the second zigzag sides intersect with said zigzag center line at a smaller angle α than that of the first zigzag sides and are inclined with respect to the axial direction to the same inclination direction as said zigzag center line with respect to the axial direction.