A heavy duty tire (1) comprising at least three rib-like land portions (7) with a block row where blocks (6) defined by circumferential main grooves (3) extending in the circumferential direction and lateral grooves (5) are arranged in the circumferential direction, wherein the lateral grooves (5) are provided, in their bottoms (S), with a sipe-forming region (Sy) having a sipe (20) which extends along the groove center line and has a width of 0.5 to 2.0 mm, and wherein the depth (DY) in the sipe-forming region (Sy) of the lateral grooves (5) is from 0.5 to 0.75 times the depth (H) of the circumferential main grooves (3), and the depth (DS) of the sipe (20) is from 0.75 to 1.0 times the depth (H) of the circumferential main grooves.