A pneumatic tire, comprising: a tread portion, a pair of sidewall portions and a pair of bead portions formed to be continuous with each other; a carcass constituted of at least one ply including a ply main body provided to extend in a toroidal shape across a pair of bead cores respectively embedded in the bead portions and respective wound-up portions each extending from the ply main body to be wound up around the corresponding bead core from the inner side toward the outer side in the tire width direction; and a recessed portion formed to be recessed on the inner side in the tire width direction at an outer surface of each sidewall portion in a region between a rim separating point and the tire maximum width position (P 1) in the sidewall portion, wherein: the maximum width in the tire width direction of the carcass is 120 % to 135 % of a distance between a pair of bead heals in a state where the tire has been assembled with a prescribed rim and inflated at the normal maximum internal pressure with no load exerted thereon; the outermost end (P 2) in the tire width direction of the carcass is disposed within a region defined in the tire radial direction between a position distanced from the innermost end in the tire radial direction of the carcass toward the outer side in the tire radial direction by 45 % of the carcass height and a position distanced from the innermost end in the tire radial direction of the carcass toward the outer side in the tire radial direction by 60 % of the carcass height in the tire-rim assembled state; thickness of each sidewall portion in the region is constant and within the range of 3.0 mm to 5.0 mm; provided that R represents a radius of curvature of the carcass at the outermost end (P 2) in the tire width direction of the carcass and H represents the carcass height in the tire-rim assembled state, R/H ≥ 0.45; and provided that R' represents a radius of curvature of the carcass and H represents the carcass height, R'/H ≥ 0.45 over the entirety of a region defined in the tire radial direction between a position distanced from the innermost end (P 3) in the tire radial direction of the carcass toward the outer side in the tire radial direction by 40 % of the carcass height H and a position distanced from the innermost end (P 3) in the tire radial direction of the carcass toward the outer side in the tire radial direction by 70 % of the carcass height H in the tire-rim assembled state. the maximum width in the tire width direction of the carcass is 120 % to 135 % of a distance between a pair of bead heals in a state where the tire has been assembled with a prescribed rim and inflated at the normal maximum internal pressure with no load exerted thereon; the outermost end (P 2) in the tire width direction of the carcass is disposed within a region defined in the tire radial direction between a position distanced from the innermost end in the tire radial direction of the carcass toward the outer side in the tire radial direction by 45 % of the carcass height and a position distanced from the innermost end in the tire radial direction of the carcass toward the outer side in the tire radial direction by 60 % of the carcass height in the tire-rim assembled state; thickness of each sidewall portion in the region is constant and within the range of 3.0 mm to 5.0 mm; provided that R represents a radius of curvature of the carcass at the outermost end (P 2) in the tire width direction of the carcass and H represents the carcass height in the tire-rim assembled state, R/H ≥ 0.45; and provided that R' represents a radius of curvature of the carcass and H represents the carcass height, R'/H ≥ 0.45 over the entirety of a region defined in the tire radial direction between a position distanced from the innermost end (P 3) in the tire radial direction of the carcass toward the outer side in the tire radial direction by 40 % of the carcass height H and a position distanced from the innermost end (P 3) in the tire radial direction of the carcass toward the outer side in the tire radial direction by 70 % of the carcass height H in the tire-rim assembled state.