A heavy duty tire comprising a pair of beads and a carcass extending on and between a first bead and a second bead out of the pair of beads, wherein the bead includes a core and an apex located radially outward of the core and including an inner apex and an outer apex, the carcass includes a carcass ply having a ply body which extends between the cores of the beads, in a meridian cross-section of the tire, a contour of the carcass includes an outwardly bulging curved portion and an inwardly recessed inversely curved portion located radially inward of the curved portion, the inversely curved portion is connected to the curved portion, a boundary between the curved portion and the inversely curved portion is an inflection point, a part or an entirety of the curved portion is represented by a first arc including the inflection point, a part or an entirety of the inversely curved portion is represented by a second arc including the inflection point, the first arc and the second arc are tangent to each other at the inflection point, each side surface of the tire includes a recess recessed inwardly, an outer portion located radially outward of the recess, and an inner portion located radially inward of the recess, and the recess is located radially outward of the inflection point, characterized in that the carcass ply includes a large number of carcass cords aligned with each other, each of the carcass cords is a steel cord, and a ratio (TU/TA) of a thickness of the inner apex at the inflection point measured along a normal line to a thickness of the apex at the inflection point measured along the normal line is not less than 30 % and not greater than 45 %, the normal line being normal to an interface between the ply body of the carcass and the apex and passing through the inflection point specified in the contour in a reference state, in which the tire is fitted on a standardized rim, the internal pressure of the tire is adjusted to 50 kPa, and no load is applied to the tire. the bead includes a core and an apex located radially outward of the core and including an inner apex and an outer apex, the carcass includes a carcass ply having a ply body which extends between the cores of the beads, in a meridian cross-section of the tire, a contour of the carcass includes an outwardly bulging curved portion and an inwardly recessed inversely curved portion located radially inward of the curved portion, the inversely curved portion is connected to the curved portion, a boundary between the curved portion and the inversely curved portion is an inflection point, a part or an entirety of the curved portion is represented by a first arc including the inflection point, a part or an entirety of the inversely curved portion is represented by a second arc including the inflection point, the first arc and the second arc are tangent to each other at the inflection point, each side surface of the tire includes a recess recessed inwardly, an outer portion located radially outward of the recess, and an inner portion located radially inward of the recess, and the recess is located radially outward of the inflection point, characterized in that the carcass ply includes a large number of carcass cords aligned with each other, each of the carcass cords is a steel cord, and a ratio (TU/TA) of a thickness of the inner apex at the inflection point measured along a normal line to a thickness of the apex at the inflection point measured along the normal line is not less than 30 % and not greater than 45 %, the normal line being normal to an interface between the ply body of the carcass and the apex and passing through the inflection point specified in the contour in a reference state, in which the tire is fitted on a standardized rim, the internal pressure of the tire is adjusted to 50 kPa, and no load is applied to the tire.