A tire has at least two annular grooves which are formed at the buttress, which extend in a tire circumferential direction, which are ring-like in shape, and which also extend so as to be directed toward an interior in the tire width direction. The at least two annular grooves include a first annular groove which is nearest to the contact patch, and a second annular groove which is farther away from the contact patch than the first annular groove. The bottoms of the first annular groove and the second annular groove are formed so as to appear arcuate in shape as viewed in a tire meridional section. The radius of curvature of the bottom of the first annular groove is greater than radius of curvature of the bottom of the second annular groove.