A heavy duty pneumatic tire comprises a tread portion provided with a circumferentially continuously extending longitudinal groove disposed on each side of the tire equator, and oblique grooves extending axially inwardly from the longitudinal groove at an inclination angle of 20 to 40 degrees with respect to the tire axial direction. The longitudinal groove is provided with a sound insulation wall disposed therein so as to rise from the groove bottom. The sound insulation wall extends continuously in the circumferential direction in a zigzag manner so as to have axially inner points and axially outer points at turning points of the zigzag. The distance between the sound insulation wall and the axially inner edge of the longitudinal groove is varied periodically in the tire circumferential direction so that the distance becomes minimal at the junctions of the longitudinal groove with the axially inner oblique grooves.