Patent ID: 6786257
Filing Date: 2004-09-07
Classification: B60C,Y10S

Abstract:
A pneumatic tire comprising:a plurality of reinforcing layers in each of which cords, which are inclined at a predetermined angle with respect to a tire circumferential direction, are provided parallel to each other; a tread provided on a top of said reinforcing layers which are laminated; and a block-shaped land portion having a sipe, said block-shaped land portion being defined on a tread surface by main grooves formed in the tire circumferential direction and by lug grooves formed in a direction intersecting with the main grooves; wherein said sipe is shaped so as to be twisted around a first central axis of twisting extending in a tire radial direction in the block shaped land portion and a second central axis of twisting extending substantially in a tire transverse direction, a position P1 of said first central axis of twisting in a region between one end surface of the block-shaped land portion and another end surface in the tire transverse direction and a position P2 of said central axis of twisting in a region between a contact patch area and a bottom of the sipe in the tire radial direction being within ranges satisfying the following expressions: 0.2 W&lE;P1&lE;0.8 W 0.2 F&lE;P2&lE;0.6 F wherein P1, P2 represent the position of the first and second central axes of twisting; W represents a distance from one end surface to the other end surface of the block-shaped land portion in the tire transverse direction; and F represents a distance from the contact patch area to the bottom of the sipe in the tire radial direction; wherein the sipe is twisted such that a self alignment torque is generated by the block so as to reduce a self alignment torque generated due to the cords provided parallel to each other in an outermost reinforcing layer of the plurality of reinforcing layers; wherein the block-shaped land portion is twisted from the contact patch area toward the bottom portion, and wherein a direction of twisting of the block shaped land portion is opposite to a direction of twisting of the sipe from the contact patch area toward the bottom of the sipe.