Pneumatic tire having sipes

A pneumatic tire having a plurality of blocks defined on a tread surface by main grooves extending in a circumferential direction of the pneumatic tire and side grooves extending in a width direction of the pneumatic tire, at least one block having at least a first sipe and a second sipe extending on the tread surface of the at least one block in zigzag and in the width direction of the tire independently of each other to communicate with the defining main grooves and spaced apart from one another to define a zigzagged block portion therebetween having a substantially uniform width disposed between opposing edges of the zigzagged block portion, wherein both wall surfaces of each sipe, the wall surfaces facing to each other, are inclined with respect to a diameter direction of the tire, constituted of triangular wall surfaces, each having two sides expanding toward a sipe bottom with a bending point of a zigzag of the sipe as an apex disposed on a contact surface of the tire and of inverse triangular wall surfaces, each having two sides narrowed toward the sipe bottom with one side of the zigzag of the sipe defining a base bending point disposed on the contact surface of the tire, and a pair of the triangular wall surfaces adjacent to each other and a pair of the inverse triangular wall surfaces adjacent to each other are alternately arranged, the zigzagged block portion having, as viewed in cross section, a first inclined section protruding from a ground contact surface of the tire that inclines outwardly relative to the diameter direction of the tire between consecutive apexes from the at least first sipe to the second sipe and a second inclined section protruding from the ground contact surface of the tire that inclines inwardly relative to the diameter direction of the tire between consecutive base bending points from the at least first sipe to the second sipe.