In a heavy duty pneumatic bias tire having a ply rating of not less than 58 and an aspect ratio of not more than 80%, a rubber volume as the product of the sum of each distance between ply cords in an inner mutually adjoining carcass ply per 50 mm, the sum of each distance between ply cords in an outer mutually adjoining carcass ply per 50 mm, and a distance between ply cords of mutually adjoining inner and outer carcass plies with respect to three or more inside carcass plies of an innermost ply group in at least a portion corresponding to a position of a maximum tire width is 500-1350 mm3, more preferably 700-1000 mm3.