Abstract: A tire has a tread portion provided with circumferential grooves. The ground contact area of the tread portion has ground contact lengths in the tire circumferential direction which include a crown ground contact length LC at the tire equator C and a shoulder ground contact length LS at a position spaced apart from the tire equator C by 80% of a half tread width Tw. The crown ground contact length LC is 0.95 to 1.05 times the shoulder ground contact length LS. Groove depths of the circumferential grooves are proportional to ground contact lengths of the ground contact area at the respective axial positions of the circumferential grooves.