A pneumatic radial tire comprising: - a directional pattern specifying a rotation direction of the tire; and - at least one lateral groove provided in a tread surface of the tire extending from a tread end to the inside, in the width direction, of a widthwise midpoint P of a tread half having the tread end, wherein, in each tread widthwise half, the tire fulfills the following: - a groove wall on a kicking-out side of the at least one lateral groove has a protruding portion protruding toward a groove wall on a stepping side,: - with reference to a point Q representing a midpoint in a tread width direction between the tread end and the widthwise midpoint P, the protruding portion extends in the tread width direction from a position between the point P and the point Q to the inside of the point P in the width direction, - the lateral groove inclines to a side of the specified tire rotation direction from the tread end toward the inside in the tread width direction, - a width of the lateral groove in the area where the protruding portion extends is narrower than that in an area where the protruding portion does not extend, and - there is a plurality of protruding portions, the protruding portions all protruding in the same direction in the tire circumferential direction, - wherein the pneumatic radial tire comprises a circumferential groove extending on a tire equatorial plane in a tread circumferential direction, further comprising at least one transverse groove that extends outwardly from the circumferential groove in the tread width direction and ends in a land portion of the tread surface and does not end in any other groove. - a directional pattern specifying a rotation direction of the tire; and - at least one lateral groove provided in a tread surface of the tire extending from a tread end to the inside, in the width direction, of a widthwise midpoint P of a tread half having the tread end, wherein, in each tread widthwise half, the tire fulfills the following: - a groove wall on a kicking-out side of the at least one lateral groove has a protruding portion protruding toward a groove wall on a stepping side,: - with reference to a point Q representing a midpoint in a tread width direction between the tread end and the widthwise midpoint P, the protruding portion extends in the tread width direction from a position between the point P and the point Q to the inside of the point P in the width direction, - the lateral groove inclines to a side of the specified tire rotation direction from the tread end toward the inside in the tread width direction, - a width of the lateral groove in the area where the protruding portion extends is narrower than that in an area where the protruding portion does not extend, and - there is a plurality of protruding portions, the protruding portions all protruding in the same direction in the tire circumferential direction, - wherein the pneumatic radial tire comprises a circumferential groove extending on a tire equatorial plane in a tread circumferential direction, further comprising at least one transverse groove that extends outwardly from the circumferential groove in the tread width direction and ends in a land portion of the tread surface and does not end in any other groove. - a groove wall on a kicking-out side of the at least one lateral groove has a protruding portion protruding toward a groove wall on a stepping side,: - with reference to a point Q representing a midpoint in a tread width direction between the tread end and the widthwise midpoint P, the protruding portion extends in the tread width direction from a position between the point P and the point Q to the inside of the point P in the width direction, - the lateral groove inclines to a side of the specified tire rotation direction from the tread end toward the inside in the tread width direction, - a width of the lateral groove in the area where the protruding portion extends is narrower than that in an area where the protruding portion does not extend, and - there is a plurality of protruding portions, the protruding portions all protruding in the same direction in the tire circumferential direction, - with reference to a point Q representing a midpoint in a tread width direction between the tread end and the widthwise midpoint P, the protruding portion extends in the tread width direction from a position between the point P and the point Q to the inside of the point P in the width direction, - the lateral groove inclines to a side of the specified tire rotation direction from the tread end toward the inside in the tread width direction, - a width of the lateral groove in the area where the protruding portion extends is narrower than that in an area where the protruding portion does not extend, and - there is a plurality of protruding portions, the protruding portions all protruding in the same direction in the tire circumferential direction, - wherein the pneumatic radial tire comprises a circumferential groove extending on a tire equatorial plane in a tread circumferential direction, further comprising at least one transverse groove that extends outwardly from the circumferential groove in the tread width direction and ends in a land portion of the tread surface and does not end in any other groove.