A run flat radial tire having a tire cross-section height of 115 mm or greater, comprising: a pair of bead portions, respective bead cores being embedded in the pair of bead portions; a pair of tire side portions respectively extending from the pair of bead portions toward the tire radial direction outside; a tread portion extending from one tire side portion to the other tire side portion; a carcass straddling the pair of bead cores, end portion sides of the carcass being anchored to the bead cores; a bead filler extending from the respective bead core toward the tire radial direction outside along an outer face of the carcass being embedded inside each bead portion, wherein each bead filler decreases in thickness on progression toward the tire radial direction outside and wherein a tire radial direction outside end portion of each bead filler enters into the respective tire side portion; a side reinforcing rubber layer that is provided to a tire side portion and that extends in a tire radial direction along an inner face of the carcass, the side reinforcing rubber layer decreasing in thickness on progression toward the bead core side and on progression toward the tread portion side; and at least one inclined belt layer (24A, 24B) that is provided at a tire radial direction outside of the carcass, that comprises plural steel cords, which are laid parallel to each other and coated with rubber, extending in a direction inclined to a tire circumferential direction, and in which, at least at one end portion side in the tire axial direction of a maximum width inclined belt layer having a largest width in the tire axial direction, the maximum width inclined belt layer and the side reinforcing rubber layer have an overlap width in the tire axial direction of 15% or greater of the tire axial direction width of the maximum width inclined belt layer, wherein an end portion on the tread portion side of the side reinforcing rubber layer overlaps with the maximum width inclined belt layer, with the carcass interposed therebetween, and an end portion on the bead core side of the side reinforcing rubber layer overlaps with one bead filler, with the carcass interposed therebetween, characterised in that a thickness of the side reinforcing rubber layer as measured along a normal line to the carcass passing through a center point between the tire radial direction outside end portion of said one bead filler and the end portion on the bead core side of the side reinforcing rubber layer in the extension direction of the carcass is 50% or less of a thickness of the side reinforcing rubber layer at a maximum width position of the carcass. a pair of bead portions, respective bead cores being embedded in the pair of bead portions; a pair of tire side portions respectively extending from the pair of bead portions toward the tire radial direction outside; a tread portion extending from one tire side portion to the other tire side portion; a carcass straddling the pair of bead cores, end portion sides of the carcass being anchored to the bead cores; a bead filler extending from the respective bead core toward the tire radial direction outside along an outer face of the carcass being embedded inside each bead portion, wherein each bead filler decreases in thickness on progression toward the tire radial direction outside and wherein a tire radial direction outside end portion of each bead filler enters into the respective tire side portion; a side reinforcing rubber layer that is provided to a tire side portion and that extends in a tire radial direction along an inner face of the carcass, the side reinforcing rubber layer decreasing in thickness on progression toward the bead core side and on progression toward the tread portion side; and at least one inclined belt layer (24A, 24B) that is provided at a tire radial direction outside of the carcass, that comprises plural steel cords, which are laid parallel to each other and coated with rubber, extending in a direction inclined to a tire circumferential direction, and in which, at least at one end portion side in the tire axial direction of a maximum width inclined belt layer having a largest width in the tire axial direction, the maximum width inclined belt layer and the side reinforcing rubber layer have an overlap width in the tire axial direction of 15% or greater of the tire axial direction width of the maximum width inclined belt layer, wherein an end portion on the tread portion side of the side reinforcing rubber layer overlaps with the maximum width inclined belt layer, with the carcass interposed therebetween, and an end portion on the bead core side of the side reinforcing rubber layer overlaps with one bead filler, with the carcass interposed therebetween, characterised in that a thickness of the side reinforcing rubber layer as measured along a normal line to the carcass passing through a center point between the tire radial direction outside end portion of said one bead filler and the end portion on the bead core side of the side reinforcing rubber layer in the extension direction of the carcass is 50% or less of a thickness of the side reinforcing rubber layer at a maximum width position of the carcass.