abstract |
A pneumatic radial tire possesses good drainage property on wet roads without adversely affecting steering stability and the like and has a tread pattern of a tread portion defined by a plurality of main slant grooves (2) each extending from a pattern centre (C) toward a tread end in a gradually expanding direction and comprised of a steeply slant segment (4) and a gently slant segment (5) extending in a region near to a side end of the tread portion without crossing any other grooves. Further, a fork-shaped groove (6) is bifurcated from the steeply slant segment (4) at a position ranging from the pattern centre (C) within 1/4 of a width (TW) of the tread portion and provided with at least two branch groove segments (7, 8) each extending without crossing any other grooves. Each of land portions (10, 11) defined between the main slant groove (2) and the fork-shaped groove (6) and between the branch groove segments (7, 8) of the fork-shaped groove (6) and tapered toward the pattern center has an included angle of 5-40°, and a surface height of a tapered zone of each of the land portions (10, 11) is gradually decreased toward a top side thereof. |