Provided is a rubber composition for tires which can prevent discoloration and improve ozone resistance while maintaining or improving good elongation at break, and further can be produced with high efficiency. Also provided are a pneumatic tire formed from the same, and a method for producing the same. Included is a rubber composition for tires, including: a rubber component; a phenylenediamine antioxidant; and a masterbatch, the masterbatch containing a specific nonionic surfactant and a silica having a BET value of 40-250 m.sup.2/g at a mass ratio of 1:5 to 1:0.15, the rubber component containing a diene rubber in an amount of 70-100% by mass per 100% by mass of the rubber component, the rubber composition including, per 100 parts by mass of the rubber component, 1.0-10.0 parts by mass of the phenylenediamine antioxidant and 0.1-5.0 parts by mass of the nonionic surfactant introduced in the form of the masterbatch.

A pneumatic tire for heavy loads comprising a bead core, a bead filler arranged on the outside in a tire radial direction of the lead core, a steel cord-containing carcass ply wound up on the outside from the inside in a fire axis direction around the bead core, a steel cord-containing chafer provided so as to cover the carcass ply from the inside in the tire radial direction, and a reinforcing sheet comprising a rubber and a cotton kneaded therein and interposed between the bead core and the carcass ply. The tire can improve durability of a bead part.

A method of production of conjugated diene rubber including a first step of polymerizing a compound represented by a following formula (1) by using a polymerization initiator to obtain a polymer block of the compound represented by the formula (1) having an active end, and a second step of polymerizing a monomer containing at least a conjugated diene compound by using the active end of the polymer block, wherein, in the formula (1), R.sup.1 is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R.sup.2 is a hydrocarbon group having 3 to 20 carbon atoms and containing a ring structure, each of R.sup.3 and R.sup.4 independently is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms which is substituted or unsubstituted, and X is arbitrary monovalent group. ##STR00001##

The present invention relates to a pneumatic tire having a pair of spaced apart bead components, a connecting carcass between the bead components, a pair of sidewalls overlying the carcass, and a rubber chafer portion adjacent to each of the sidewalls and positioned around at least a portion of each of the bead components and intended for contacting a rigid rim of a wheel, the rubber chafer portion comprising a radially innermost toe guard and a chafer adjacent to a radially outer end of the toe guard; wherein the ratio of a modulus of the toe guard to a modulus of the chafer is in the range of 3 to 10.

The present invention provides a conjugated diene-based polymer composition excellent in rolling resistance, grip performance on a wet road surface, and abrasion resistance when formed into a tire. Also provided is a conjugated diene-based polymer composition containing: 10 to 90 parts by mass of a conjugated diene-based polymer (A) having a glass transition temperature of ?20? C. or more; and 10 to 90 parts by mass of a conjugated diene-based polymer (B) having a glass transition temperature of ?25? C. or less, wherein the conjugated diene-based polymer (A) has an absolute molecular weight, measured by viscosity detector-equipped GPC-light scattering measurement, of 40?10.sup.4 or more and 5000?10.sup.4 or less, and a branch number (Bn), measured by the viscosity detector-equipped GPC-light scattering measurement, of 8 or more.

Provided is a pneumatic tire. The cap tread layer is made of a rubber composition in which 50 parts by mass to 100 parts by mass of silica and 5 parts by mass to 25 parts by mass of carbon black are blended per 100 parts by mass of diene rubber containing 50 mass % or more of natural rubber and 20 mass % or more and 40 mass % or less of styrene-butadiene rubber. As the styrene-butadiene rubber, terminal-modified styrene-butadiene rubber having a vinyl content of 35 mass % to 70 mass % is used. As the carbon black, carbon black having a nitrogen adsorption specific surface area N.sub.2SA of less than 130 m.sup.2/g is used. The rubber composition constituting the cap tread layer is set to have a tensile product TB?EB of 12000 or more and a hardness of 60 or more and 70 or less.

A pneumatic tire comprising a tread, a sidewall, a bead portion having a bead core, a bead reinforcing layer reinforcing the bead portion, and a carcass ply moored on a bead core of the bead portion, wherein the bead reinforcing layer and adjacent members adjacent to the bead reinforcing layer are each composed of a rubber composition containing an amine type antioxidant, 0.3 to 8 parts by mass of the amine type antioxidant is contained in the bead reinforcing layer based on 100 parts by mass of the rubber component, the adjacent member adjacent to the bead reinforcing layer and the bead reinforcing layer satisfy the following formula.

3B/A8

A: Content (wt %) of amine type antioxidant in bead reinforcing layer
B: Content (wt %) of amine type antioxidant in the adjacent member

The present invention provides a pneumatic tire having improved durability while maintaining or improving good handling stability. The present invention relates to a pneumatic tire including an outer apex formed from a rubber composition, the rubber composition having a thermal conductivity of 0.60 W/m.Math.K or higher.

Provided is a pneumatic tire in which an electric resistance can be reduced without adversely affecting other performances such as tire durability or manufacturing processes even when low loss of a rubber member of the tire is attempted. The pneumatic tire includes a belt layer 2 provided at an outer side of a crown portion of a carcass 1 in a tire radial direction, and a rubber chafer 4 is provided at an outer surface of a bead portion in a tire width direction. A cushion rubber 13C and a tread rubber 13G are sequentially provided at an outer side of the belt layer in the tire radial direction, and a composite fiber 3 containing a conductive fiber and a non-conductive fiber extends at least from the bead portion to a position in contact with the cushion rubber or a belt under cushion arranged at an outer end portion of the belt layer in the tire width direction in such a manner as to be exposed on at least one surface the carcass at either the outer and inner sides of the tire, and the rubber chafer contains a carbon black having a nitrogen adsorption specific surface area of 30 to 43 m.sup.2/g.

A tire includes a pair of beads, a carcass, chafers, an insulation, and cushion layers. Each bead includes a core positioned inward of the bead in a radial direction. At an inside of the core in the radial direction, the insulation is laminated on the chafers so as to be located outward of the chafers in the radial direction. Each cushion layer is laminated on the insulation so as to be located outward of the insulation in the radial direction. The insulation and the cushion layer are formed from respective crosslinked rubbers different from each other. A compressive elastic modulus E* of the crosslinked rubber of the cushion layer is smaller than a compressive elastic modulus E* of the crosslinked rubber of the insulation.