Abstract: A circumferential narrow main groove extending in a circumferential direction in a tread of a pneumatic tire. The circumferential narrow main groove includes a narrow portion opening to a road contact surface of the tread and a widened portion having a wider groove width than the narrow portion. The widened portion is at a groove bottom. A groove width ratio (W2/W1) of a maximum groove width W2 of the widened portion to a groove width W1 of the narrow groove portion is in a range 1.5?(W2/W1)?4.0, and a cross-sectional area ratio (A2/A1) of a groove bottom-side cross-sectional area A2 to a groove opening-side cross-sectional area A1 in a meridian cross-section is within a range 1.2<(A2/A1)<4.0 when the circumferential narrow main groove is divided into two parts at 50% of a maximum groove depth of the circumferential narrow main groove. The cross-sectional area ratio changes along the circumferential direction.

Abstract: A pneumatic tire includes the belt layer that is formed by laminating the circumferential reinforcing layer and the pair of cross belts. Also, the tire external diameter R at the point of intersection O of the tire equatorial plane CL and the tread profile, the distance D1 in the tire radial direction between the tire ground contact edge T and the point of intersection O, and the distance D2 in the tire radial direction between the foot X of the line drawn from the end portion on the outer side in the tire width direction of the circumferential reinforcing layer 145 normal to the tread profile and the point of intersection O have a relationship such that 0.010?D1/R?0.015 and 0.27?D2/D1?0.3.

Abstract: A pneumatic tire includes the belt layer that is formed by laminating the circumferential reinforcing layer and the pair of cross belts. Also, the tire external diameter R at the point of intersection O of the tire equatorial plane CL and the tread profile, the distance D1 in the tire radial direction between the tire ground contact edge T and the point of intersection O, and the distance D2 in the tire radial direction between the foot X of the line drawn from the end portion on the outer side in the tire width direction of the circumferential reinforcing layer 145 normal to the tread profile and the point of intersection O have a relationship such that 0.010?D1/R?0.015 and 0.27?D2/D1?0.3.