Pneumatic tire

A pneumatic tire, comprising:

• a tread portion extending in a tire circumferential direction in an annular shape;
• a pair of sidewall portions disposed on either side of the tread portion;
• a pair of bead portions disposed on an inside in a tire radial direction of the sidewall portions;
• and at least one layer of a carcass layer disposed between the pair of bead portions;
• wherein
• a ratio SW/OD of a total tire width SW and a tire outer diameter OD satisfies a relationship SW/OD≤0.3, the total tire width SW being set in a range from 125 mm to 185 mm and the tire outer diameter OD being set in a range from 650 mm to 850 mm;
• in a tire meridian cross-section, a contour of the tread portion that forms a tread profile includes side arcs located on outermost sides in a tire width direction of the tread portion, and shoulder arcs located on an inner side in the tire width direction of the side arcs;
• a pair of first boundary lines is defined passing through an intersection point of an extension line of the side arcs and an extension line of the shoulder arcs and perpendicular to a tire inner surface;
• each sidewall portion has a rim check line extending in the tire circumferential direction;
• in a tire meridian cross-section, a pair of second boundary lines is defined passing through the rim check lines and perpendicular to the tire inner surface;
• a first region is partitioned between the pair of first boundary lines;
• a second region is partitioned between the first boundary line and a second boundary line;
• a third region is partitioned on a bead toe side of the second boundary line;
• when cross-sectional areas (mm2) of the first region through third region are SA, SB, and SC respectively, and peripheral lengths (mm) of the first region through third region along the tire inner surface are a, b, and c respectively, a ratio SA/a satisfies a relationship 7.5≤SA/a≤11.5;
• the tread portion has a tread pattern formed by grooves, and a groove area ratio GR in a ground contact region of the tread pattern is 25% or less;
• a linear density of carcass cords of the carcass layer is from 1200 dtex/2 to 1300 dtex/2, and a cord count per 50 mm unit width of the carcass layer is from 55 to 70 cords;
• a bead filler is disposed on an outer periphery side of each of the bead cores, a height of the bead filler in the tire radial direction being less than a height of the rim check line in the tire radial direction;
• and
• at least one inclined reinforcing layer including a plurality of reinforcing cords inclining with respect to the tire circumferential direction is disposed on an outer circumferential side of the carcass layer in the tread portion, an inclination angle of the reinforcing cords of the at least one inclined reinforcing layer with respect to the tire circumferential direction being from 40° to 45°.