A standard grounding surface shape F0 becomes a maximum grounding length Lc at a tire equator C and becomes a shortest grounding length Lm between the tire equator C and a grounding edge TE. The shortest grounding length Lm is located in a region away from the tire equator C by a distance of 0.5 to 0.9 times of a tread half width TW. A rubber thickness t1 between the carcass cord and the belt cord is gradually increased outward in the axial direction of the tire from the tire equator, and the rubber thickness t1 in a half width position Q which is away from the tire equator by a distance of 0.55 times of the tread half width TW is set to 0.5 to 3.0 mm. A ratio t2q/t2c between a tread entire thickness t2c in the half width position Q and a tread entire thickness t2c in the tire equator is set to 1.010.05.