Abstract: In addition to dramatic improvement of on-ice performance, to balance with other performances. A pneumatic tire comprises, in a tread portion 1, at least two block groups GB1 to GB3 whose block number density is within a range of 0.003 pieces/mm2 to 0.04 pieces/mm2. At least one block group GB2 includes block 4 in which lateral length BW2 is larger that its longitudinal length BL2.

Abstract: In a tire, a phase difference L1 of transverse grooves 2 is within 25% of the length L of blocks 3, the projected portions 11 are alternately on both sidewalls 10, L2 of the portion 11 is 20% to 45% of L, and in the cross-section of the width direction of the main groove 1, the edge 15 of the portion 11 at the groove bottom is more of a sidewall 10 side than a center line 19 of the groove 1, the outline of the portion 11 is at least on a virtual surface 17 that connects the edge 13 of the groove 1 at the tread surface and the edge 15. The tire also has one or a plurality of sub-projected portions 21, 22 projected from the surface 17.

Abstract: A heavy duty pneumatic tire comprises a tread portion provided with circumferentially continuous main grooves and lateral grooves to form blocks in circumferential rows. The main grooves include a pair of shoulder main grooves disposed one on each side of the tire equator so that the center line thereof is at a distance of 0.30 to 0.65 times one half of the tread width from the tire equator. The blocks include crown blocks disposed in a tread crown region between the shoulder main grooves, and shoulder blocks disposed in shoulder regions axially outside the shoulder main grooves. Each of the crown blocks and shoulder blocks is provided with at least one axially extending sipe.

Abstract: A pair of motor vehicle tyres includes a front tyre and a rear tyre to be mounted respectively on a front wheel and a rear wheel of a two-wheeled vehicle, each tyre of the pair having a tread band extending around an axis of rotation. The tread band of the front tyre includes a central annular portion straddling an equatorial plane and two annular shoulder portions disposed on axially opposite sides of the central annular portion. The central annular portion includes at least a pair of first grooves extending substantially longitudinally on opposite sides of the equatorial plane in such a way as to form a concavity directed toward the equatorial plane. Each shoulder portion includes a plurality of second grooves isolated from the first grooves and extending substantially transversally so as to form an average inclination with the equatorial plane greater than 90°.

Abstract: A method for manufacturing a base tire ensuring a cure-molding of a green tire therefor without overcure or undercure in the thin-walled shoulder portions of the tread region and the bead regions, a curing machine that preferably enables the base tire manufacturing method, and a base tire thus manufactured are provided. To that end, a base tire is enclosed within a curing mold, the side regions of the base tire are heated by a first heating means, the tread region of the base tire is heated by a second heating means, and a cure-molding is performed such that the amount of heat given to the tread region by the second heating means is smaller than the amount of heat given to the side regions by the first heating means.

Abstract: A construction vehicle tire, in which a temperature rise at the tread portion is suppressed by enhancing the heat radiation property at the tire center portion (C). Lug grooves (22) are arranged in the tread shoulder regions (S) on both sides in the tire width direction. The tire center portion (C) is formed with narrow grooves (24) extending substantially in the tire width direction (V) and having both ends terminating within the tread. A deep equatorial groove (26) extends in the tire circumferential direction on the tire equatorial plane (CL), and has a maximum depth within the range of from 70% to 110% of the depth of the lug grooves (22), so as to efficiently cool the bottom region (26B) of the deep equatorial groove (26) at high temperature.

Abstract: A vehicle wheel tire center tread region has a repeating circumferential array of first substantially V-shaped grooves positioned on the centerplane, each first V-shaped groove having divergent first groove side arms extending in a first circumferential direction, and a repeating circumferential array of second substantially V-shaped grooves positioned on the centerplane and having divergent second groove side arms extending in a second circumferential direction opposite to the first circumferential direction. Each first V-shaped groove is overlapped by multiple oppositely directed second V-shaped grooves. The first V-shaped groove arms have a varying lengthwise depth that varies between about 2 and 7 millimeters from a shallower depth proximate to a vertex arm region to an increased depth at a medial arm region to a decreased depth at a terminal arm region.

Abstract: A method of improving tire tread noise is provided. The method allows the identification of locations where the tread pattern should be particularly modified in order to optimize the level of noise created by the tread during tire operation. Variations in a defined parameter, contact length ratio, are used to determine one or more locations in the tread pattern where modification for noise reduction can be made. The type of modifications needed can also be indicated.

Abstract: The present invention provides: a rubber composition for a tire that achieves both good fuel economy and abrasion resistance, and also achieves good degradation resistance and processability; and a heavy-load tire having a tread produced therefrom. The present invention relates to a rubber composition for a tire, comprising a rubber component that contains a modified natural rubber having a phosphorus content of 200 ppm or less and a butadiene rubber, wherein the amount of the modified natural rubber is 60 to 95% by mass and the amount of the butadiene rubber is 5 to 40% by mass, based on 100% by mass of the rubber component.

Abstract: A method of manufacturing a new tire having a reinforced rubber structure and a polyurethane tread.

Abstract: A tire and a method for forming a tire tread are disclosed. The tire includes a tread defining an inferior tread profile and a superior tread profile, the superior tread profile having a generally continuous curvature between an edge of contact and a top center point. The superior tread profile includes a plurality of control points and a plurality of splines. Each of the plurality of splines extends between at least two of the plurality of control points. Curvatures of adjacent splines are generally equal at each of the plurality of control points.

Abstract: A pneumatic tire includes a tire component having a plurality of individually dipped and tackified cords applied individually to the tire component.

Abstract: The present invention provides a rubber composition for a studless tire capable of improving the performance on snow and ice, wet performance, abrasion resistance in good balance, and a studless tire having a tread produced from the rubber composition. The rubber composition for a studless tire includes a rubber component including modified natural rubber and butadiene rubber; aromatic oil; silica; and carbon black, wherein the amount of the aromatic oil is 15 to 80 parts by mass and the amount of the silica is 15 to 80 parts by mass, relative to 100 parts by mass of the rubber component.

Abstract: The present invention aims to provide a rubber composition for a tire which can improve the performance on snow and ice, abrasion resistance and tensile strength in a well-balanced manner. The present invention also aims to provide a method for producing the rubber composition and a studless tire having a cap tread produced from the rubber composition. The rubber composition for a tire is obtainable by mixing a rubber component containing natural rubber and butadiene rubber with silica at a temperature of 70 to 130° C. to form a mixture, and keeping the mixture at a temperature of 150 to 200° C.

Abstract: A motorcycle tire for running on rough terrain comprises a tread portion having a unidirectional tread pattern and provided with T-sided blocks having a top surface, a heel-side sidewall surface extending from a heel-side edge of the top surface, and a toe-side sidewall surface extending from a toe-side edge of the top surface. The heel-side sidewall surface has an inclination angle ? of from 0 to 15 degrees. The toe-side sidewall surface has a radially outer region having a height of from 20 to 55% of the block height and inclined at an angle ? of from 20 to 45 degrees. A radially inner region of the toe-side sidewall surface has: a central part inclined at the same angle ? as the radially outer region; a pair of lateral parts located one on each side of the central part and having an inclination angle ? of from 0 to 15 degrees; and a pair of stepped parts extending between the lateral parts and the central part in a direction crosswise to the toe-side edge.

Abstract: A motorcycle tire for running on rough terrain comprises a tread portion provided with a plurality of blocks including a cut block. The cut block is provided with a U-shaped cut so as to define a sub part of the cut block surrounded by the cut and a main part of the cut block outside the cut. The top surface of the sub part and the top surface of the main part are displaced from each other in a normal direction to the tread surface, and an exposed outside wall surface of the sub part and an exposed outside wall surface of the main part are displaced from each other in a lateral direction parallel with the tread surface, wherein the exposed outside wall surface of the sub part is defined as extending radially inwardly from the edge of the top surface of the sub part, and the exposed outside wall surface of the main part is defined as extending radially inwardly from the edge of the top surface of the main part and positioned on each side of the exposed outside wall surface of the sub part.

Abstract: A pneumatic tire has a carcass structure having at least one carcass ply and at least one annual reinforcing structure associated with the carcass ply, a tread band made of an elastomeric material at a radially outer position with respect to the carcass structure, a belt structure interposed between the carcass structure and the tread band and a pair of axially opposite side walls on the carcass structure, wherein the tread band has i) at least one first sector, radially extending, substantially of a first elastomeric material; ii) a plurality of second sectors radially extending, positioned at axially opposite sides of the at least one first sector and substantially of a second elastomeric material; iii) at least one longitudinal groove formed in the at least one first sector and extending substantially for the entire circumferential development of the tread band, wherein the first elastomeric material has a modulus of elasticity under compression at 23° C.

Abstract: Prepolymers having active NCO groups are disclosed. The prepolymers are the reaction product of at least one polyisocyanate and a polyhydric component which comprises at least one dimer fatty derivative diol or diamine that is a natural oil based polyol or polyamine which includes the derivative of at least one dimer fatty acid. Polyurethane and polyurea elastomer obtained from the prepolymers are also disclosed. Also disclosed are methods of manufacturing polyurethane or polyurea treaded tires.

Abstract: A rubber composition for a tire, in which a specific tackifier is compounded, and tackiness and various physical properties are improved, compared with compounding a petroleum resin or a terpene resin, is provided. The rubber composition for a tire comprising an alkyd resin and a pneumatic tire using the same. It is preferable that a material derived from a resource other than petroleum, particularly, a material derived from animal and/or vegetable, and more particularly, a material derived from an animal oil and/or a vegetable oil is contained in the alkyd resin, and it is preferable that unsaturated polybasic acid is contained in the alkyd resin.

Abstract: This invention relates to a pneumatic rubber tire having a rubber tread of a cap/base construction. More specifically, the invention relates to a tire having a tread with minimized, or inhibited, base peaking.

Abstract: To improve water evacuation property while preventing uneven wear, as well as to significantly improve the on-ice/snow performances by optimizing a tread pattern. This pneumatic tire has, in at least a part of a tread portion 1, a small block group GB, the small block group including a plurality of small blocks 3 arranged close together. The small block group GB comprises at least one circumferential main groove positioned 4 including see-through groove portion which linearly extends in the tread circumferential direction and at least one rib-like land portion 6 provided adjacently to the circumferential main groove and forming a groove side face 5 of the circumferential main groove 4 and continuously extending in the circumferential direction. A number density D of the small blocks is set within a range of 0.003 to 0.04 (pieces/mm2), the number density D representing the number of the small blocks per unit of an actual ground contact area of the small block group.

Abstract: A tire formed from a resin material is provided having a high stress withstanding ability and capable of maintaining a high internal pressure. By configuring the side sections 14 with plural circular arc curve faced portions 32 having curvature in the circumferential direction formed successively along the circumferential direction the stress acting on the side sections 14 can be distributed at a radial direction stress and a circumferential direction stress. Accordingly, the radial direction stress can be reduced further than in a conventional profile not provided with any circular arc curve faced portions along the circumferential direction, enabling sufficient pressure withstanding ability (internal pressure) to be secured for a pneumatic tire for use on a vehicle even though a thermoplastic material with weaker stress than that of rubber is employed for the side sections 14.

Abstract: This skew-symmetric non-pneumatic tire focuses on the mechanical aspects of the design of the design to solve problems associated with the ride comfort, durability and assembly of a non-pneumatic tire. The tire has a generally cylindrical hub surrounding the axis of rotation and a generally cylindrical outer surface sharing the common axis of rotation; a pair of disk-like side wall members comprising non-buckling webs extending between and mating with their respective hub and outer cylindrical surface; said pair of side wall members have webs sharing a common configuration resulting in an assembly with a skew-symmetric structure with respect to the loading direction; and a tread-band circumscribing the cylindrical outer surfaces of the side walls.

Abstract: The present invention provides a pneumatic tire with reduced air columnar resonance noise level in comparison with the conventional pneumatic tires. The pneumatic tire comprises large-volume oblong holes 11 formed in a sidewall 10a on one side of a main groove 1 and small-volume oblong holes 12 formed in a sidewall 10b on the other side thereof, respectively, in which a width w1 and a depth d1 of the large-volume oblong hole 11 are at least not less than 0.4 mm and more than 0.05 times but less than 0.25 times a width W of the main groove 1, and a space p1 between the large-volume oblong holes 11 is at least not less than 0.8 mm and more than 0.2 times but less than 1.0 times the width W, a width w2 and a depth d2 of the small-volume oblong hole 12 are at least not less than 0.2 mm and more than 0.01 times but less than 0.05 times the width W, and a space p2 between the small-volume oblong holes 12 is at least not less than 0.4 mm and more than 0.04 times but less than 0.

Abstract: A pneumatic tire in which K1, as derived from a contour range L1 and a developed tread width TDW by formula (1) below, satisfies 0.6?K1?0.9, and K2, as derived from a curvature radius TR1 of the center portion arc and a external tire diameter OD by formula (2) below, satisfies 2.0<K2. K1=L1/(TDW×0.

Abstract: The present invention is directed to a pneumatic tire comprising a tread, the tread comprising a ground contacting rubber composition comprising a diene based elastomer and short fibers, wherein the short fibers extend lengthwise in a substantially axial direction of the tire.

Abstract: There is provided a rubber composition for a tread having excellent hardness and improving the processability and grip performance of a tire, and a tire comprising thereof. A rubber composition for a tread comprising 30 to 80 parts by weight of silica having a BET specific surface area of less than 150 m2/g and 10 parts by weight or less of carbon black based on 100 parts by weight of a rubber component comprising an epoxidized natural rubber, and a tire comprising thereof.

Abstract: Embodiments of the invention are used to provide ways of tire tread molding and retreading with a double tread rubber body having a unitary structure that comprises two treads in order to remove the need for buffing an oxide layer typically associated with tread molding and curing. Embodiments of the double tread molding and retreading methods also remove the need for cementing the cured tread to prevent future oxidation buildup. Once the double tread is cured and cooled, it is cut along the centerline with a double tread separation apparatus to expose a soft non-oxidized inner rubber. The cutting is much less energy intensive when compared to buffing with an expendable wire brush. There is no risk of spots of oxidized rubber being missed as is the case with buffing. There is little or no dust created.

Abstract: A tyre for motor vehicles, in particular for rear wheels of motor vehicles, has a tread band including an annular central portion, two first annular side portions and two second annular side portions, each arranged between the annular central portion and a respective first annular side portion and being narrower than the first annular side portion.

Abstract: A rubber composition obtained by compounding thereinto a rubber component containing 0.5 to 100% by weight of a modified conjugated diene-based polymer having a fullerene bonded thereto in the molecule and having a weight average molecular weight of 50,000 or more excellent processability, superior balance of modulus and heat buildup, excellent cold flowability and superior tan ? balance.

Abstract: A pneumatic tire has a carcass structure having at least one carcass ply and at least one annular reinforcing structure associated with the carcass ply, a pair of axially opposite side walls on the carcass structure, a belt structure arranged at a radially outer position with respect to the carcass structure and a tread band arranged at a radially outer position with respect to the belt structure, and generally having a first elastomeric material incorporating at least one portion substantially of a second elastomeric material. The tread band has at least one groove defined in the at least one portion substantially of the second elastomeric material, wherein the ratio between the modulus of elasticity under compression at 100° C. of the second elastomeric material and the modulus of elasticity under compression at 100° C. of the first elastomeric material is not lower than about 1.30, and wherein the ratio between the IRHD hardness at 100° C.

Abstract: Provided is a tire exhibiting improved wear resistance, partial wear resistance, and traction performance on the wet road surface. The tire has block land portion arrays 5 defined on a tread portion 1. Between two block land portion arrays 5 located adjacent to each other while sandwiching a circumferential groove 2, a block land portions 4 constituting the block land portion arrays are arrange so as to be positionally displaced from each other, and a groove portion 6 located between the block land portions adjacent in the tire width direction extends obliquely with respect to tire width direction and the tire circumferential direction. At this time, a distance d2 between the block land portions adjacent in the tire width direction is shorter than a distance d1 between the block land portions adjacent in the circumferential direction.

Abstract: A rubber composition for use in tires is described which provides increased fuel efficiency and improved wet grip performance. The rubber composition includes from 5 to 70 parts by mass of silica having a BET specific surface area from 50 to 200 m2/g per 100 parts by mass of a diene rubber. The rubber composition includes from 1 to 25 parts by mass of an aromatic modified terpene resin and at least one terpene per 100 parts by mass of a diene rubber. The rubber composition further includes from 1 to 70 parts by mass of a naphthenic oil per 100 parts by mass of a diene rubber, where a CN % proportion of a CA %·CP %·CN % ratio calculated according to ASTM D2140/ASTM D3238 is the greatest and the CA % proportion is less than 15%, and a dynamic viscosity at 40° C. is from 17 to 30 mm2/sec.

Abstract: The object is to provide a precured tread for a retreaded tire improving attachability to a base tire. In a strip-shaped precured tread 10 to be attached to a crown portion of a base tire 32 from which a tread has been removed, side tread rubbers 14 disposed in side regions CS on both sides of a central region CN are set to have JIS A hardness lower than that of a central tread rubber 12 disposed in the central region CN including a widthwise centerline C so as to improve attachability to a base tire.

Abstract: Particular embodiments of the present invention include tire treads that include a tread body having a length, a width, and thickness, the thickness being bounded by an outer surface and an underside surface. Such treads may also include a void positioned within the thickness of the tread body. Such treads may further include one or more members extending between the void and the tread underside surface. Other embodiments of the present invention include a tire having such treads, as well as molds for forming such treads.

Abstract: An airplane tire, whose rated pressure is more than 9 bar and whose deflection under rated load is more than 30%, comprising a tread having a tread surface (41), a crown reinforcement (42) comprising at least one layer of reinforcing elements, and a carcass reinforcement (43) comprising at least one layer of reinforcing elements; said tread surface (41), crown reinforcement (42) and carcass reinforcement (43) being defined geometrically by respective initial meridian profiles. The initial meridian profile of the crown reinforcement (42) is locally concave across a central part whose axial width l42 is at least 0.25 times the axial width L42 of the crown reinforcement.

Abstract: The rubber composition for a tire base tread includes a rubber component containing not less than 15% by weight of a terminal-modified diene rubber having a number average molecular weight prior to modification of 150000 to 400000, a filler, and a compound (vulcanizing agent) represented by the following general formula (1) in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the rubber component: (wherein R represents a benzyl group, and n represents an integer of 3 to 12.

Abstract: A heavy duty tire is vulcanized in a segmented mold having a tread molding surface defined by circumferentially arranged segments. The tread portion is molded by the tread molding surface during vulcanization of the tire, wherein the stretch of the belt layer in the tire radial direction during vulcanization is in a range of from 3.2 to 5.2%. the tread portion is provided with an axially outermost circumferential groove at an axial distance from the tire equator which distance is in a range of from 50% to 68% of one half of the tread width. The footprint shape satisfies the following conditions: (1) 1.05=<SL0/SL70=<1.18; and (2) 0.95=<SL70/SL97=<1.05, wherein SL0, SL70 and SL97 are the circumferential lengths of the footprint shape measured at axial distances of 0%, 70% and 97%, respectively, of one half of the tread width from the tire equator.

Abstract: The present invention is directed to a cured pneumatic tire having a built-in innermost adhesive layer co-cured and thereby integral therewith and post tire cure applied sealant thereon.

Abstract: A method for forming a vulcanizable composition of matter, the method comprising providing a polymer cement or latex comprising at least one rubber, adding at least one processing aid to the cement or latex to form a modified rubber cement or latex, isolating the rubber and at least one processing aid to form a premix, and mixing the premix with carbon black.

Abstract: Pneumatic rubber tire with an outer, circumferential tread comprised of specialized cis 1,4-polybutadiene rubber based silica/carbon black reinforced rubber composition.

Abstract: A center block and a second block that satisfy h1/H=0.05 to 0.4 and w1/W=0.05 to 0.4 are formed on a tread, where H is the block height, h1 is the drop in height of a chamfered part, w1 is the breadth of the chamfered part and W is the length of the block tread in a circumferential direction. When traveling on hard pavement, the chamfered part of the block contacts the hard pavement first and, compared to a case in which an edge that does not have a chamfered part contacts a hard pavement, the ground-contact surface area can be increased and steering stability on hard pavement can be improved. Further, in rough terrain, resistance received from a road surface at the time of ground contact is reduced, travel resistance is suppressed and steering stability is improved.

Abstract: The present invention is directed to a catalyst system for synthesizing rubbery polymers, such as polybutadiene rubber, styrene-butadiene rubber, isoprene-butadiene rubber, or styrene-isoprene-butadiene rubber, that are amine functionalized and have a high trans microstructure. The catalyst system, in one embodiment, includes (a) an organolithium amine compound, (b) a group IIa metal salt of an amino glycol or a glycol ether, (c) an organoaluminum compound, and optionally (d) an amine compound. The amine functionalized rubbery polymers can be utilized in tire tread rubbers where the rubbery polymers may provide desirable wear properties without substantially sacrificing other performance characteristic(s), e.g., traction properties.

Abstract: A pneumatic tire comprises a tread portion provided with: an inside circumferential groove (3) near the tread edge (Ti); 1st axial grooves (4) extending from the inside circumferential groove (3) toward the tire equator (C); oblique grooves (5) extending from the respective 1st axial grooves (4) to the outside tread edge (To), while inclining to the opposite direction to the intended tire rotational direction (R); 2nd axial grooves (6) extending from the inside circumferential groove (3) to the oblique grooves (5); and connecting grooves (7) extending between the oblique grooved 5. The tread portion (2) is provided with bent blocks (B1) each made up of an axial part (11) and oblique part (12). The bent point (E1) of the bent block (B1) is positioned on the inside tread edge side of the tire equator (C), and the axial distance (L1) therebetween is 0.10 to 0.25 times the tread width (TW).

Abstract: A heavy-duty tire having a tread portion improved in the shoulder wear is disclosed. Under the maximum load condition[W100], the tread portion has a ground contacting face G[W100] having circumferential lengths L97[W100] and L70[W100] at specific axial positions. Under the 70% load condition[W70], the tread portion has a ground contacting face G[W70] having lengths L97[W70] and L70[W70] at specific axial positions. The lengths L70[W100], L97[W100], L70[W70] and L97[W70] satisfy specific conditions: 0.95<L70[W100]/L97[W100]<1.05; and 1.03<L70[W70]/L97[W70]<1.20.

Abstract: A vehicle tire having a sidewall and an undertread, the sidewall, the undertread or both being based upon a rubber composition, the rubber composition comprising a highly unsaturated diene elastomer, a carcass grade carbon black and particles comprising at least 70 wt. % unsulfonated lignin, wherein the particles make up no more than 50 wt. % of the total weight of the particles and the carbon black.

Abstract: The tire transient response data obtained while cornering with a slip angle is calculated based on a tire dynamic model. The deformation response of a tread part in the tire dynamic is set as a first-order-lag response. The value of the transient response parameter is initialized in order to define the first-order-lag response. The time-series data of the transient response of the slip angle between the tread part and the road surface in the tire dynamic model is obtained by computing the convolution integral of the defined response function of the first-order-lag response with a time gradient of the time-series data of the slip angle. The value of a lateral force is calculated by using the tire dynamic model based on the time-series data of the transient response of the slip angle thus obtained. Accordingly, the transient response data is calculated and the value of the transient response parameter is obtained.

Abstract: A tire tread and a tire comprising a tire tread, the tire tread having a rubber composition based on a diene elastomer; more than 50 phr of an inorganic filler as reinforcing filler; between 2 and 15 phr of an inorganic filler/diene elastomer coupling agent; between 1 and 10 phr of a methylene acceptor, and between 0.5 and 5 phr of a methylene donor. The tread may be characterized as having a radially increasing rigidity gradient from the surface towards the inside of the tread after mechanical run-in of the tread. In particular embodiments, the tread may be characterized as having a nominal secant modulus at 10% elongation is between 3 and 7 MPa at a radially outer surface of the tread and between 9 and 13 MPa at the most radially inside of the tread.

Abstract: A rubber composition, wherein a reaction efficiency of a silane coupling agent at kneading is improved, generation of air bubbles is suppressed, abrasion resistance is improved, and rolling resistance is lowered, is provided. A rubber composition containing silica, which comprises 3 to 15 parts by weight of a silane coupling agent based on 100 parts by weight of silica, and boric acid.

Abstract: The present invention provides a rubber composition and a pneumatic tire using the rubber composition. The rubber composition which comprises: a rubber component comprising a styrene-butadiene copolymer rubber or a blend of the styrene-butadiene copolymer rubber and another conjugated diene base rubber with the styrene-butadiene copolymer rubber being 70% by weight or more of the entire blend, and the entire content of styrene is 30 to 40% by weight of the entire rubber component; silica in an amount of 10 to 60 parts by weight per 100 parts by weight of the rubber component; a specific silane coupling agent, i.e., a bis (alkoxysilylalkyl)polysulfide having a polysulfide chain in which the distribution of sulfur is specified, in an amount of 1 to 20% by weight of the amount of silica; and carbon black, the sum of the amount of silica and carbon black being 60 to 130 parts by weight per 100 parts by weight of the rubber component.