A run-flat tire comprises a tread portion, sidewall portions, bead portions, and a carcass ply extending between the bead portions. The sidewall portions are each provided therein with a sidewall reinforcing rubber layer having a crescent-shaped cross sectional shape and disposed on the axially inside of the carcass ply. The sidewall portions are each provided in the axially outer surface thereof with a rim protector which projects radially outward most on the radially outside of the radially inner edge of the sidewall reinforcing rubber layer. The bead portions are each provided therein with an axially inside core and an axially outside core between which each radially inner edge portion of the carcass ply is secured. When measured along a normal line drawn normally to the carcass ply from an apex of the rim protector, the thickness of the sidewall reinforcing rubber layer is in a range of from 29% to 35% of the thickness of the tire.

A tire includes: a pair of bead portions in which a bead core is each embedded and that have a bead heel diameter that is from 0.42% to 0.72% smaller than a rim diameter of a standard rim; a carcass that spans a region between the pair of bead portions and that has end portion sides anchored to the bead cores; bead filler that extends from each bead core toward a tire radial direction outer side so as to run along an outer face of the carcass; and side reinforcing rubber that is provided at tire side portions, that extends in the tire radial direction along an inner face of the carcass, that has an end portion at each bead core side overlapping the bead filler with the carcass interposed therebetween, and that has elongation at break of 130% or greater.

In an apex 34 of a tire 2, a reinforcing portion 48 is located inward of a main body 46 in an axial direction. When a position on an outer surface of the tire 2 at which position a height from a BBL is 14 mm is defined as a first point P1 and a position on the outer surface of the tire 2 at which position a height from the BBL is 20 mm is defined as a second point P2, the reinforcing portion 48 overlaps the first point P1 and the second point P2 in a radial direction. A loss tangent of the reinforcing portion 48 is equal to a loss tangent of the main body 46 or less than the loss tangent. A hardness of the reinforcing portion 48 is equal to a hardness of the main body 46 or greater than the hardness.

The tire maximum width in the reference condition is the center value or more and the upper limit or less of the tire maximum width specified in the standard, and the tire maximum width position in the reference condition is located at the position, with a distance of more than 50% of the tire cross-sectional height, outward in the tire radial direction from the bead baseline.

A tire (10) comprises a crown block (12), two beads (32), and two sidewalls (30) connecting each bead (32) to the crown block (12). The crown block (12) comprises a crown reinforcement (16) comprising a corrugated crown layer (24, 26, 28) comprising corrugations. The tire (10) comprises a sidewall insert (90) comprising a rigid elastomeric composition (92, 93, 94) of which the radially exterior end (96) is arranged: radially to the outside of the equator (E) of the tyre, and axially to the inside of the axial end (241, 242) of the radially innermost crown layer (24) of the crown reinforcement (16) and at an axial distance ENG20 mm from the axial end (242).

A tire (10) not suitable for running flat comprises a crown block (12), two beads (32), and two sidewalls (30) connecting each bead (32) to the crown block (12). The crown block (12) comprises a crown reinforcement (16) comprising a corrugated crown layer (24, 26, 28) comprising corrugations. The sidewall (30) comprises a sidewall insert (90) comprising an elastomeric composition (92) referred to as a rigid elastomeric composition having a modulus at 10% extension greater than or equal to 6 MPa and a maximum thickness (Emax) less than or equal to 5.0 mm.

Provided is a run flat tire comprising a side reinforcing layer on a sidewall part, wherein a rubber composition of the side reinforcing layer has a complex elastic modulus at 100 C. (E*.sub.100) of 5.0 to 17 MPa and a loss tangent at 60 C. (60 C. tan ) of 0.020 to 0.100 MPa, and wherein, where a tire cross-sectional width is defined as Wt (mm) and a tire outer diameter is defined as Dt (mm), Wt and Dt satisfy any of the following inequality (1), (2), and (3):
Wt<225 and Dt59.078Wt{circumflex over ()}0.460(1)
225Wt<235 and Dt59.078Wt{circumflex over ()}0.620967.673(2)
235Wt and DtWt{circumflex over ()}0.6+750(3)