High wet braking performance is obtained without causing deterioration to other aspects of performance.Circumferential direction grooves 14 are configured with first groove portions 16 of zigzag shape formed at the road surface side and second groove portions 18 of straight line shape formed at the groove bottom side. Accordingly, an effect (edge effect) is effectively exhibited by the edges of the first groove portions 16 catching on the road surface when running on a comparatively shallow water depth. High wet braking performance is accordingly obtained. Water in the grooves flows smoothly due to the presence of the second groove portions 18 at the groove bottom side when running on a comparatively deep water depth. Reliable ground contact performance of the tread surface of the tread 12 to the road surface and high wet braking performance is accordingly obtained. High wet braking performance can be secured irrespective of whether there is shallow or deep water due to the edge effect of the first groove portions 16 and due to the water expelling effect of the second groove portions 18.