The present invention relates to self-supporting tyres for vehicle wheels having sidewall reinforcement inserts (113) with reduced rigidity. These tyres have a good mileage in flat running conditions, greater comfort and significantly reduced rolling resistance compared to known self-supporting tyres, with higher modulus sidewall reinforcement inserts.

The present invention relates to a self-supporting tire for vehicle wheels comprising a carcass structure comprising at least one carcass ply having a plurality of hybrid reinforcing cords (10) each comprising at least two strands (20) twisted to each other with a predetermined stranding pitch (P), wherein each of said at least two strands (20) comprises at least one monofilament textile thread (21) at least partially embedded in the filaments (22a) of at least one multifilament textile yarn (22) and a pair of sidewall reinforcement inserts (113), where at least one of said sidewall reinforcement inserts comprises a vulcanised elastomeric compound which has a dynamic shear modulus value G equal to or less than 1.25 MPa measured at 70° C., 10 Hz, 9% deformation according to the RPA method reported in the present description.

At a run-flat tire, given that an average radius of curvature of a case line between an intersection point (0.1SHp) and an intersection point (0.2SHp) when viewed in a cross-section along a tire rotation axis is radius R1, and that an average radius of curvature of the case line between an intersection point (0.4SHp) and an intersection point (0.6SHp) when viewed in the cross-section along the tire rotation axis is radius R2, ratio R2/R1 is set to be greater than 0.3.

Provided is a run-flat tire. A first bead filler is disposed on an outer circumferential side of a bead core, a second bead filler is disposed on an outer side in a tire width direction of a turned up portion of the carcass layer along the turned up portion of the carcass layer, and a thickness G on a first reference line of a side reinforcing layer, a thickness G1 on a second reference line of the side reinforcing layer, and a thickness G2 on a third reference line of the side reinforcing layer satisfy the relationships of 0.8×G≤G1≤1.0×G and 0.5×G≤G2≤0.7×G.

The run-flat tire of this disclosure includes a tread portion, a pair of sidewall portions continuous, bead portions, side reinforcing rubbers with crescent-like cross section, and a carcass, wherein: when the tire is mounted to a rim, and an internal pressure of 250 kPa or more is applied, in a case where a sectional width SW of the tire is less than 165 mm, a ratio of the sectional width SW to an outer diameter OD of the tire, SW/OD, is 0.26 or less; and in a case where the sectional width SW of the tire is 165 mm or more, the sectional width SW and the outer diameter OD of the tire satisfy a relation expression OD≧2.135×SW+282.3 (mm); and when H1 is a tire radial maximum length of the side reinforcing rubber in a tire widthwise cross section in a reference state, a relation expression 10 (mm)≦(SW/OD)×H1≦20 (mm) is satisfied.

The run-flat tire of this disclosure includes a tread portion, a pair of sidewall portions, bead portions, side reinforcing rubbers with crescent-like cross section, and a carcass formed of plies of radially arranged cords, wherein: when the tire is mounted to a rim, and an internal pressure of 250 kPa or more is applied to the tire, in a case where a sectional width SW of the tire is less than 165 mm, a ratio of the sectional width SW to an outer diameter OD of the tire, SW/OD, is 0.26 or less; in a case where the sectional width SW of the tire is 165 mm or more, the sectional width SW and the outer diameter OD of the tire satisfy a relation expression OD≧2.135×SW+282.3 (mm); and the relation expression 0.5≦WG/WB≦0.8 is satisfied.

The run-flat tire of this disclosure includes a tread portion, a pair of sidewall portions, bead portions, side reinforcing rubbers with crescent-like cross section, a carcass formed of plies of radially arranged cords, wherein: when the tire is mounted to a rim, and an internal pressure of 250 kPa or more is applied to the tire, in a case where a sectional width SW of the tire is less than 165 mm, a ratio of the sectional width SW to an outer diameter OD of the tire, SW/OD, is 0.26 or less; in a case where the sectional width SW of the tire is 165 mm or more, the sectional width SW and the outer diameter OD of the tire satisfy a relation expression OD≧2.135×SW+282.3 (mm); the bead portions have bead cores, and further have bead fillers; and the relation expression 1.8≦H1/H2≦3.5 is satisfied.

In a tire 2, load support layers 20 extend, in portions inward of a carcass 10, from portions inward of beads 8, respectively, in the axial direction to portions inward of a tread in the radial direction. When a reference point P represents a point, on an outer surface of the tire 2, which is distant from a bead base line by 25 mm in the radial direction, a distance D1, at the reference point P, from the outer surface of the tire 2 to an outer side surface of a main portion 36 of a carcass ply 34 is greater than or equal to 3 mm and not greater than 10 mm.

The pneumatic tire includes: a pair of bead portions; a pair of sidewall portions; a tread portion; a carcass; a reinforcing rubber layer, a tire widthwise cross-section of the reinforcing rubber layer having a substantially crescent shape; an inclined belt including at least one inclined belt layer formed by a plurality of cords extending at an inclination to a tire circumferential direction and covered with rubber; and an inner liner provided on an inner peripheral surface of a tire body in at least the tread portion. In a tire widthwise cross-sectional view, an edge of the inner liner is positioned farther outward in the tire radial direction than a tire maximum width position of the pneumatic tire and farther inward in the tire radial direction than a perpendicular from a tire widthwise edge of the inclined belt to the inner peripheral surface of the tire body.

A method of preparing a sidewall support, the method comprising the steps of (i) providing a vulcanizable composition including an elastomer, a filler, a curative, and a eutectic composition; (ii) fabricating the vulcanizable composition into a green sidewall support; and (iii) subjecting the green sidewall support to curing conditions.