Run-flat tire

A run-flat tire with a tire section height of at least 129 mm, the run-flat tire comprising:

• a carcass bridging between a pair of bead portions;
• a tire side portion that links the bead portions with a tread portion, a carcass maximum width position of the tire side portion, at which a width of the carcass is at a maximum, being disposed at the tire radial direction outer side relative to a position at 40% of the tire section height;
• a side reinforcement layer provided at a tire width direction inner side of the carcass, a thickness of the side reinforcement layer at the position at 40% of the tire section height being at most 65% of a thickness thereof at the carcass maximum width position;
• first and second tread circumferential grooves that are disposed in the tread portion and adjacent to each other such that a space between the first and second grooves is entirely on one side of a tire equatorial plane, the first groove being closer to the equatorial plane than the second groove;
• a plurality of tread reinforcement layers disposed so that, as viewed from the tire radial direction, all of the tread reinforcement layers overlap with the second groove;
• wherein a tire width direction most inner end, of a tread reinforcement layer that is disposed at a tire radial direction most outer side, is disposed in the space between the first and second grooves;
• wherein each bead portion comprises (1) a bead core such that each bead core is embedded in each bead portion, and (2) a bead filler such that each bead filler is embedded in each bead portion;
• wherein the bead filler extends from the bead core toward the tire radial direction outer side along an outer face of the carcass, and wherein a height of the bead filler is within a range from 30% to 50% of the tire section height;
• wherein an end portion of the bead filler is disposed at the tire radial direction inner side relative to the maximum width position of the carcass;
• and
• wherein a distance in the tire radial direction between a lower end portion of the bead core and a lower end portion of the side reinforcement layer is from 50% to 80% of the height of the bead filler.

A run-flat tire with a tire section height of at least 129 mm, the run-flat tire comprising:

• a carcass bridging between a pair of bead portions;
• a tire side portion that links the bead portions with a tread portion, a carcass maximum width position of the tire side portion, at which a width of the carcass is at a maximum, being disposed at the tire radial direction outer side relative to a position at 40% of the tire section height;
• a side reinforcement layer provided at a tire width direction inner side of the carcass, a thickness of the side reinforcement layer at the position at 40% of the tire section height being at most 65% of a thickness thereof at the carcass maximum width position;
• first and second tread circumferential grooves that are disposed in the tread portion and adjacent to each other such that a space between the first and second grooves is entirely on one side of a tire equatorial plane, the first groove being closer to the equatorial plane than the second groove;
• a plurality of tread reinforcement layers disposed so that, as viewed from the tire radial direction, all of the tread reinforcement layers overlap with the second groove;
• wherein a tire width direction most inner end, of a tread reinforcement layer that is disposed at a tire radial direction most outer side, is disposed in the space between the first and second grooves;
• wherein each bead portion comprises (1) a bead core such that each bead core is embedded in each bead portion, and (2) a bead filler such that each bead filler is embedded in each bead portion;
• wherein the bead filler extends from the bead core toward the tire radial direction outer side along an outer face of the carcass, and wherein a height of the bead filler is within a range from 30% to 50% of the tire section height;
• wherein an end portion of the bead filler is disposed at the tire radial direction inner side relative to the maximum width position of the carcass;
• wherein a distance in the tire radial direction between a lower end portion of the bead core and a lower end portion of the side reinforcement layer is from 50% to 80% of the height of the bead filler;
• wherein the side reinforcement layer comprises a rubber member that (1) structures the tire width direction outer side relative to the side reinforcement layer and the carcass, and (2) possess the characteristics that a JIS hardness measured at 20° C. using a durometer hardness tester is 70-85, and a loss coefficient tan δ measured using a viscoelasticity spectrometer is not more than 0.10 under conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ±2%, and a temperature of 60° C.;
• and
• wherein a thickness of the side reinforcement layer at position at 40% of the tire section height, is formed to be a thickness that is at least 10% of the thickness of the side reinforcement layer at the carcass maximum width position.