Abstract: A pneumatic tire having a plurality of main grooves extending in the circumferential direction of a tread surface, and a plurality of auxiliary grooves each of which is disposed in the shape of the letter "V" and extended in one of the circumferential directions of the tread surface, the apexes of the V-shaped auxiliary grooves being distributed in left and right regions each extending from the equator of the tire as much as 5-25% of the width of a ground contacting portion of the tread surface, in such a manner that the numbers of the apexes in the left and right regions become substantially equal to each other, characterized in that quasi-main grooves each of which connects at least two circumferentially arranged auxiliary grooves together are provided in left and right regions each extending from the equator of the tire as much as 25-50% of the width of a ground contacting portion of the tread surface, in such a manner that the quasi-main grooves are inclined at an angle of 5.degree.-25.degree.

Abstract: A pneumatic radial tire for heavy-duty vehicles in which reinforcement belts comprising metal cords are disposed in the tread portion, and a plurality of main grooves extending in the circumferential direction of the tire are provided in the tread surface. In addition, recessed and projecting portions are provided on the edges of the tread surface in a zig-zag fashion along the circumferential direction of the tire.

Abstract: A pneumatic tire wherein a plurality of main grooves are provided in a tread of the tire in the circumferential direction thereof with a plurality of sub-grooves connecting these main grooves with each other being provided in the width-wise direction of the tire, wherein each of these sub-grooves is bent in a convex shape facing in the same direction relative to the circumferential direction of the tire, and wherein bending points of the sub-grooves are distributed within those areas in the tread of the tire which extend, respectively, from a tire equator line toward opposite sides of the tire in the width-wise direction thereof over a distance equal to 5 to 25% of the tread ground-contacting width in such a manner that the number of the bending points become substantially equal on either side of the equator line.