Patent ID: 7182113

Claim:
A pneumatic tire, comprising: a tread portion in which at least one rib groove extended in a tire circumferential direction is formed on a tread surface portion, and portions discontinuous in terms of rigidity are formed in a circumferential direction of rib lines formed by the rib groove, the discontinuous portions causing variations of tire axle force, wherein rigidity changing portions which cancel the variations of the tire axle force, caused by the discontinuous portions, are provided in the rib groove, wherein the rigidity changing portions include protruding portions which are formed on a wall surface of the rib groove and increase rigidity against tread compression, and wherein each protruding portion is protruded from the wall surface so that a planar shape of the protruding portion forms a substantially circular arc with a planar surface on a tip and a cross-section of the protruding portion forms a substantially triangular shape in a manner that a protruding amount is gradually reduced from a bottom surface of the rib groove toward an opening portion of the rib groove.