Provided are: a rubber-reinforcing fiber, in which adhesion between a rubber and a fiber is enhanced and which is thereby capable of further improving the durability than before when used as a reinforcing material; a rubber-fiber composite; and a pneumatic tire using the same. The rubber-reinforcing fiber includes a core-sheath type composite fiber whose core portion is composed of a high-melting-point resin (A) having a melting point of 150 C. or higher and sheath portion is composed of a resin material (B) having a melting point lower than that of the high-melting point resin (A). The resin material (B) includes: an olefin-based random copolymer (C) and/or an olefin-based homopolymer or olefin-based copolymer (D) (excluding (C)); and a styrene-based elastomer (E) containing a monomolecular chain in which mainly styrene monomers are arranged in series.

Provided are: a rubber-reinforcing fiber, in which adhesion between a rubber and a fiber is enhanced and which is thereby capable of further improving the durability than before when used as a reinforcing material; a rubber-fiber composite; and a pneumatic tire using the same. The rubber-reinforcing fiber includes a core-sheath type composite fiber whose core portion is composed of a high-melting-point resin (A) having a melting point of 150 C. or higher and sheath portion is composed of a resin material (B) having a melting point lower than that of the high-melting point resin (A). The resin material (B) includes: an olefin-based random copolymer (C) and/or an olefin-based homopolymer or olefin-based copolymer (D) (excluding (C)); and a styrene-based elastomer (E) containing a monomolecular chain in which mainly styrene monomers are arranged in series.

Provided are: a rubber-reinforcing fiber, in which adhesion between a rubber and a fiber is enhanced and which is thereby capable of further improving the durability than before when used as a reinforcing material; a rubber-fiber composite; and a pneumatic tire using the same. The rubber-reinforcing fiber includes a core-sheath type composite fiber whose core portion is composed of a high-melting-point resin (A) having a melting point of 150 C. or higher and sheath portion is composed of a resin material (B) having a melting point lower than that of the high-melting point resin (A). The resin material (B) contains an olefin-based polymer (X) and a vulcanization accelerator (F).

Provided are: a rubber-reinforcing fiber, in which adhesion between a rubber and a fiber is enhanced and which is thereby capable of further improving the durability than before when used as a reinforcing material; a rubber-fiber composite; and a pneumatic tire using the same. The rubber-reinforcing fiber includes a core-sheath type composite fiber whose core portion is composed of a high-melting-point resin (A) having a melting point of 150 C. or higher and sheath portion is composed of a resin material (B) having a melting point lower than that of the high-melting point resin (A). The resin material (B) contains an olefin-based polymer (X) and a vulcanization accelerator (F).

The present invention provides a pneumatic tire having excellent fuel efficiency, handling stability, and ride quality while maintaining a good balance between them. Provided is a pneumatic tire including a tire component formed from a rubber composition, the rubber composition having cured rubber properties satisfying predetermined values.

Flat reinforcer having the shape of a multicomposite strip (R1, R2, R3) defining three main perpendicular directions, the axial direction (X), the transverse direction (Y) and the radial direction (Z), having a width W.sub.R measured along the Y direction of between 2 and 100 mm and having a thickness T.sub.R measured along the Z direction of between 0.1 and 5 mm, the aspect ratio W.sub.R/T.sub.R being greater than 3, this multicomposite strip comprising at least: a plurality of monofilaments (10, 20) made of composite material, orientated along the X direction, comprising filaments of a mineral material (101) embedded in a thermoset resin (102), the glass transition temperature of which, denoted Tg.sub.1, is greater than 70 C.; this plurality of monofilaments (10, 20) being coated in a layer of thermoplastic material (12); all or some of these monofilaments (10, 20) being flat monofilaments, of cross section having a width W.sub.M measured along the Y direction and having a thickness T.sub.M measured along the Z direction, with an aspect ratio W.sub.M/T.sub.M greater than 1.5.

Multilayer laminate comprising such a multicomposite reinforcer. Pneumatic or non-pneumatic tyre reinforced by such a multicomposite reinforcer or multilayer laminate.

Flat reinforcer having the shape of a multicomposite strip (R1, R2, R3) defining three main perpendicular directions, the axial direction (X), the transverse direction (Y) and the radial direction (Z), having a width W.sub.R measured along the Y direction of between 2 and 100 mm and having a thickness T.sub.R measured along the Z direction of between 0.1 and 5 mm, the aspect ratio W.sub.R/T.sub.R being greater than 3, this multicomposite strip comprising at least: a plurality of monofilaments (10, 20) made of composite material, orientated along the X direction, comprising filaments of a mineral material (101) embedded in a thermoset resin (102), the glass transition temperature of which, denoted Tg.sub.1, is greater than 70 C.; this plurality of monofilaments (10, 20) being coated in a layer of thermoplastic material (12); all or some of these monofilaments (10, 20) being flat monofilaments, of cross section having a width W.sub.M measured along the Y direction and having a thickness T.sub.M measured along the Z direction, with an aspect ratio W.sub.M/T.sub.M greater than 1.5.

Multilayer laminate comprising such a multicomposite reinforcer. Pneumatic or non-pneumatic tyre reinforced by such a multicomposite reinforcer or multilayer laminate.

A run-flat tire having a tread, an inner liner disposed beneath the tread, a body ply, and a pair of sidewalls axially spaced apart from one another is disclosed. The run-flat tire further includes a pair of sidewall-reinforcing portions each disposed in respective sidewall regions and each having a fabric barrier; a first sidewall-reinforcing insert between the fabric barrier and the inner liner; and a second sidewall-reinforcing insert disposed between the fabric barrier and the body ply. The fabric barrier extends not more than an entire length of the sidewall-reinforcing portion.

A run-flat tire having a tread, an inner liner disposed beneath the tread, a body ply, and a pair of sidewalls axially spaced apart from one another is disclosed. The run-flat tire further includes a pair of sidewall-reinforcing portions each disposed in respective sidewall regions and each having a fabric barrier; a first sidewall-reinforcing insert between the fabric barrier and the inner liner; and a second sidewall-reinforcing insert disposed between the fabric barrier and the body ply. The fabric barrier extends not more than an entire length of the sidewall-reinforcing portion.

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 comprising a rubber component containing 20% by mass or more of a modified conjugated diene based polymer, satisfying Expression (1) in terms of the elongation X under a stress of 6.5 MPa at 180 C. and the elongation Y under a stress of 6.5 MPa at 25 C. after vulcanization.

1.00X/Y1.15 (1)