Pneumatic tire with ground contact surface of land portion having circular arcs

A pneumatic tire includes a tread surface having a plurality of main grooves extending straight in a circumferential direction of the tire. The plurality of main grooves defines land portions extending in the tire circumferential direction. The land portions each have a ground contact surface comprising a first circular are having a single curvature radius in tire meridian cross section. The ground contact surface of at least the land portion which is located second when counted from the outer side of a vehicle when the tire is mounted thereon, is arranged so as to have the first circular are and at least a second circular are connected thereto on the vehicle outer side thereof. The circular are located closer to the vehicle outer side has a smaller curvature radius and is positioned more inwardly away from the tread surface. The ratio d/D of the depth d of an intersection of the circular are located closest to the vehicle outer side with a vehicle outer sidewall surface of the at least second land portion to the groove depth D of the main groove facing to the vehicle outer sidewall surface is 0.02 to 0.1.