In a side reinforced type run-flat tire, a relationship between a distance (Do) from a center position of a circumferential primary groove that is positioned outermost in the tire width direction in a vehicle outer side region to a tire equatorial plane and a rim width (Wr) is such that 0.20Do/Wr0.30, and a relationship between a distance (Di) from a center position of a circumferential primary groove that is positioned outermost in the tire width direction in a vehicle inner side region to the tire equatorial plane and the rim width (Wr) is such that 0.25Di/Wr0.35.

A run flat tire is provided having a line L1 connecting point P1 having height H1 of 17 mm; and point P2 at which a thickness from point P1 is minimum thickness Ts. Point C represents a point which is distant from point P2 on line L1 by a distance that is 0.4 times Ts. A point B represents a point of intersection of: line L2 that extends in the axial direction through radially outer end of core 36; and line L3 that extends in the radial direction through an axially outer end of core side portion 46a of turned-up portion 46. A line L4 passes through point C and point B. The thickness Ts is greater than or equal to 10 mm, and not greater than 17 mm. The turned-up portion 46 extends through a region surrounded by an axially outer surface of main portion 44, and lines L2-L4.

A run flat tire having a side reinforcing rubber part is disclosed. The side reinforcing rubber part is formed by a rubber composition having a ratio (M50H/M50N) of tensile stress (M50H) in 50% elongation at a measurement temperature of 100 C. to tensile stress (M50N) in 50% elongation at a measurement temperature of 23 C. of from 1.0 to 1.3. A ratio (M50H/M50F) of tensile stress (M50H) in 50% elongation at a measurement temperature of 100 C. of the rubber composition forming the side reinforcing rubber part to tensile stress (M50F) in 50% elongation at a measurement temperature of 100 C. of a rubber composition forming a bead filler is from 0.5 to 1.3.

A tire includes a tread formed in a crown region of the tire and sidewall regions extending from the crown region to bead areas. The tire further includes a toroidal element extending across a crown region of the tire, and further extending along at least a portion of each sidewall region of the tire. The toroidal element has a central region located between inner and outer regions. The central region is more elastic than the inner and outer regions.

A run flat tire having a side reinforcing rubber part is disclosed. The side reinforcing rubber part is formed by a rubber composition having a ratio (M50H/M50N) of tensile stress (M50H) in 50% elongation at a measurement temperature of 100 C. to tensile stress (M50N) in 50% elongation at a measurement temperature of 23 C. of from 1.0 to 1.3. Ratio (t.sub.b10/t.sub.p10) of 10% vulcanization time (t.sub.b10) at a vulcanization temperature of 160 C. of a rubber composition for a bead filler to 10% vulcanization time (t.sub.p10) at a vulcanization temperature of 160 C. of a rubber composition for a covering rubber of a carcass ply is from 0.5 to 1.0.

A run-flat tire 1 comprises a carcass 6, a pair of side reinforcing rubber layers 9, and a pair of sidewall rubber components 10. At a tire maximum-width position, a first side reinforcing rubber layer 9A disposed in the side of a first bead portion has a thickness B1 greater than a thickness B2 of a second side reinforcing rubber layer disposed in the side of a second bead portion, and a first sidewall rubber component disposed in the side of the first bead portion has a thickness A1 smaller than a thickness A2 of a second sidewall rubber component disposed in the side of the second bead portion.

In a side reinforcing type run flat tire, a minimum wall thickness portion is arranged between an end portion of each belt layer and a position at 70% of a tire cross-sectional height SH. A relationship between a thickness G.sub.min of the minimum wall thickness portion and a thickness G.sub.max of a maximum wall thickness portion 17 is 0.5G.sub.maxG.sub.min0.8G.sub.max. A relationship between a length L min of a thin wall region and the tire cross-sectional height SH is 0.18SHL.sub.min0.26SH. A relationship among a weight Wr of a side reinforcing layer, a total weight Wt of the tire, and a tire flattening rate R is 0.08Wt(10.2(1R/50))Wr0.18Wt(10.2(1R/50)). A relationship between a thickness Ga at a rim check line position of an outer side rubber portion more to the outer side than a carcass layer and a maximum thickness Gb thereof is 0.8GbGa1.0Gb.

The present invention provides a tire improved in the run flat durability, having at least one member selected from the group consisting of a side reinforcing rubber layer and a bead filler using a rubber composition having a tensile stress at 50% elongation at 180 C. (M50) of 6.2 MPa or more as a vulcanized rubber physical property.

In a tire 2, each load support layer 22 extends from a side portion 24 of the tire 2 to a radially inner side of a belt 14 at an inner side of a carcass 12. A ratio (SP/WB) of a width SP from an equator plane to an outer edge 48 of the load support layer 22, relative to a width WB from the equator plane to an edge of the belt 14, in an axial direction is equal to or greater than 0.1 and equal to or less than 0.6.

A runflat tire includes a tire body, a carcass extending from a tread portion through sidewall portions of the tire body to bead cores in bead portions of the tire body, and sidewall-reinforcing rubber layers having cross-sectional crescent shapes and positioned on inner sides of the carcass along the sidewall portions, respectively. The tire body has height Ha in range of 817 mm where the height Ha is measured from a rim line of the tire body to inner edge of an innermost dimple/fin row of the tire body in radial direction of the tire body, the innermost row is formed in dimple/fin forming region including one or more dimple/fin rows having dimple/fin portions arrayed in circumferential direction of the tire body, and the dimple/fin forming region is formed on external surface of a sidewall portion on outer side of the rim line in the radial direction.