A pneumatic radial tire for high-speed running vehicles has a directional tread pattern defined by one or two relatively wide circumferential grooves arranged in the central region and plural slant grooves arranged in each side region of the tread, and an aspect ratio of not more than 0.8. In this tire, the slant grooves are arranged in a herringbone form with respect to the equator without communicating with the circumferential groove, each of which extending from an initial end to a terminal end and being a folded line at a folding point corresponding to 0.3-0.45 times of the tread width that an inclination angle .alpha. of line segment inward from the folding point is 40.degree.-85.degree. with respect to the meridian of the tire and an inclination angle .beta. of line segment outward from the folding point is smaller than the inclination angle .alpha. and 0.degree.-50.degree. with respect to the meridian of the tire.