PURPOSE: To sufficiently prevent generation of riven wear and generation of pebble-holding.

CONSTITUTION: Respective opposite groove walls 4, 5 of a zigzag groove 3 located in close proximity to at least a tread end are curved in the outside area in the radial direction of a tire, and the depth (h) of the curved positions is taken as 0.25 ≤h/H≤0.5 eith respect to the depth H of the zigzag groove. Angles of intersection of each part in the outer area and the inside area in the tire-radial direction of the respective groove walls 4, 5 with the tread normal line at the part curved in the tread-shoulder direction in a projected manner of the zigzag groove 3, and at the part curved in the tread-center direction in a projected manner, are specified.