Heavy duty pneumatic tire

A heavy duty pneumatic tire, comprising:

• a tread;
• a pair of side walls extending from edges of the tread substantially inward in a radial direction, respectively;
• a pair of beads positioned inward with respect to the side walls in an axial direction, respectively;
• a carcass extending between the beads along an inner side of the tread and inner sides of the side walls;
• a pair of bead fillers laminated outward with respect to the beads in the axial direction, respectively;
• and
• a pair of fitting portions configured to fit to a rim such that each of the fitting portions comprises a chafer configured to make contact with the rim and a clinch positioned outward with respect to a respective one of the bead fillers in the axial direction,
• wherein each of the beads includes a core and an apex extending outward with respect to the core in a radial direction, the carcass includes a carcass ply folded back around the core from an inner side of the core toward an outer side of the core in the axial direction such that the carcass ply has a main portion positioned between the beads and a folding-back portion positioned outward with respect to the beads in the axial direction, each of the bead fillers is laminated outward with respect to the folding-back portion of the carcass ply in the axial direction and has an outer edge positioned outward with respect to a bead base line in the radial direction and an inner edge positioned inward with respect to the bead base line and outward with respect to a bead toe in the radial direction, each of the fitting portions includes a bottom surface configured to make contact with a seat surface of the rim and an outer-side contact surface extending from the bottom surface outward in the radial direction and configured to make contact with a flange of the rim, the outer-side contact surface has an inner-side portion, an outer-side portion and a middle portion formed between the inner-side portion and the outer-side portion in the radial direction such that when the heavy duty pneumatic tire is not mounted to the rim, the middle portion is recessed inward with respect to an imaginary straight line L1 passing through an outer edge Pa of the inner-side portion and an outer edge Pb of the outer-side portion in the axial direction, each of the fitting portions satisfies a ratio Tb/Tc in a range of 1.5 to 3.0 where Tb represents a thickness of the clinch at the outer edge Pb of the outer-side portion, Tc represents a thickness of the clinch at a point Pc of the middle portion corresponding to a midpoint between the outer edge Pa of the inner-side portion and the outer edge Pb of the outer-side portion, and each of the fitting portions has the middle portion recessed in an arc shape at a depth D in a cross section perpendicular to a circumferential direction such that a ratio D/Rd is in a range of from 0.05 to 0.09 where Rd represents a curvature radius of the arc shape.