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 each of the beads includes a core and an apex located radially outward of the core, the apex including an inner apex and an outer apex located radially outward of the inner apex, the carcass includes a carcass ply having a ply body which extends between the cores of the beads, the carcass ply includes a large number of carcass cords aligned with each other, each of the carcass cords is a steel cord, 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, and the first arc and the second arc are tangent to each other at the inflection point, characterized in that a ratio (X/W) of a distance in an axial direction from an equator plane of the tire to the inflection point to a distance in the axial direction from the equator plane to an axially outer end of the contour of the carcass is not less than 70 % and not greater than 85 %, a ratio (Y/H) of a distance in a radial direction from a bead base line of the tire to the inflection point to a distance in the radial direction from the bead base line to a point of intersection of the contour of the carcass and the equator plane is not less than 15 % and not greater than 22 %, 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 0.30 and not greater than 0.45, 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 normal rim, the internal pressure of the tire is adjusted to 50 kPa, and no load is applied to the tire. each of the beads includes a core and an apex located radially outward of the core, the apex including an inner apex and an outer apex located radially outward of the inner apex, the carcass includes a carcass ply having a ply body which extends between the cores of the beads, the carcass ply includes a large number of carcass cords aligned with each other, each of the carcass cords is a steel cord, 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, and the first arc and the second arc are tangent to each other at the inflection point, characterized in that a ratio (X/W) of a distance in an axial direction from an equator plane of the tire to the inflection point to a distance in the axial direction from the equator plane to an axially outer end of the contour of the carcass is not less than 70 % and not greater than 85 %, a ratio (Y/H) of a distance in a radial direction from a bead base line of the tire to the inflection point to a distance in the radial direction from the bead base line to a point of intersection of the contour of the carcass and the equator plane is not less than 15 % and not greater than 22 %, 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 0.30 and not greater than 0.45, 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 normal rim, the internal pressure of the tire is adjusted to 50 kPa, and no load is applied to the tire.