A pneumatic radial tire having a tread surface divided into a first half portion and a second half portion across a tire equator as a boundary, the first half portion having a first circumferential main groove extending in the tread circumferential direction, the second half portion having two circumferential main grooves (2b, 2c) including a second circumferential main groove and a third circumferential main groove both extending in the tread circumferential direction, the first half portion having only one circumferential main groove, and the second half portion having only two circumferential main grooves (2b, 2c), wherein the circumferential main groove of the first half portion and the two circumferential main grooves (2b, 2c) of the second half portion each have a groove width (W1, W2, W3) of 7 mm to 15 mm, wherein the first circumferential main groove in the first half portion has a groove wall on the tread width direction outside which is inclined relative to the tire radial direction at a larger inclination angle (β1) as compared to an inclination angle (α1) relative to the tire radial direction of a groove wall on the tread width direction inside, wherein, the second circumferential main groove in the second half portion lies inside in the tread width direction and the third circumferential main groove in the second half portion lies outside in the tread width direction, wherein, of the two circumferential main grooves (2b, 2c) in the second half portion, the second circumferential main groove has a groove wall on the tread width direction outside which is inclined relative to the tire radial direction at a larger inclination angle (β2) as compared to an inclination angle (α2) relative to the tire radial direction of a groove wall on the tread width direction inside, wherein, of the two circumferential main grooves (2b, 2c) in the second half portion, the third circumferential main groove has a groove wall on the tread width direction inside which is inclined at a larger inclination angle (β3) relative to the tire radial direction as compared to an inclination angle (α3) relative to the tire radial direction of a groove wall on the tread width direction outside, wherein "inside" and "outside" are defined with respect to the tire equator, wherein, in the first circumferential main groove in the first half portion, a tapered portion having a large inclination angle (γ1) relative to the tire radial direction is provided only on the groove wall on the tread width direction inside of the first circumferential main groove in the first half portion, the inclination angle (γ1) of the tapered portion of the first circumferential main groove being defined as 15° to 40°, wherein, in the second circumferential main groove of the two circumferential main grooves (2b, 2c) in the second half portion, a tapered portion having a large inclination angle (γ2) relative to the tire radial direction is provided only on the groove wall on the tread width direction inside of the second circumferential main groove in the second half portion, the inclination angle (γ2) of the tapered portion of the second circumferential main groove being defined as 15° to 40°, wherein, in the third circumferential main groove of the two circumferential main grooves (2b, 2c) in the second half portion, a tapered portion having an inclination angle (γ3) relative to the tire radial direction is provided only on the groove wall on the tread width direction outside of the third circumferential main groove in the second half portion, the inclination angle (γ3) of the tapered portion of the third circumferential main groove being defined as 15° to 40°, and wherein the inclination angles (α1, α2, α3) of the groove walls (5b, 6a, 7b) provided with the tapered portions (5c, 6c, 7c) are inclination angles of the groove walls (5b, 6a, 7b) on the most inner side in the radial direction rather than inclination angles (γ1, γ2, γ3) of the tapered portions (5c, 6c, 7c).