Abstract: A heavy duty pneumatic radial tire is disclosed, which comprises a tread portion, a pair of side portions, a pair of bead portions each reinforced with a bead ring, a radial carcass ply, a metal cord reinforcing layer and a composite rubber filler. In this tire, the carcass ply is a rubberized layer of aromatic polyamide fiber cords and a tip of its turnup portion terminates at a position lower than an upper end of a rim flange when the tire is mounted on a rim. In the metal cord reinforcing layer, one end facing the turnup portion terminates over the tip of the turnup portion and the other end facing the carcass ply extends toward the side portion over a position corresponding to the above-mentioned one end facing the turnup portion.