The present invention relates to a tire tread comprising a tread cap comprising at least one tread cap rubber compound, at least three circumferential grooves, wherein at least portions of the sidewalls and the bottom of each of said grooves are formed by a circumferential groove reinforcement, and wherein a first groove reinforcement of a groove laterally next to the equatorial plane of the tire comprises a first reinforcement rubber compound which has a higher hardness than the tread cap rubber compound, and wherein a second groove reinforcement of a groove with a larger lateral distance to the equatorial plane of the tire than the first groove, comprises a second reinforcement rubber compound which has a higher hardness than the tread cap rubber compound and a lower hardness than the second reinforcement rubber compound.

Provided are a rubber composition for tires that shows a balanced improvement in properties such as fuel economy, processability, heat aging resistance, abrasion resistance, wet-grip performance, performance on snow and ice, and handling stability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for tires, containing: a highly purified, modified natural rubber having a pH adjusted to 2-7; carbon black and/or a white filler; and a silane coupling agent represented by the following Formula (S1): ##STR00001##
wherein R.sup.1001 represents a monovalent group selected from —Cl, —Br, —OR.sup.1006, —O(O═)CR.sup.1006, —ON═CR.sup.1006R.sup.1007, —ON═CR.sup.1006R.sup.1007, —NR.sup.1006R.sup.1007, and —(OSiR.sup.1006R.sup.1007).sub.h(OSiR.sup.1006R.sup.1007R.sup.1008), wherein R.sup.1006, R.sup.1007, and R.sup.1008 are the same as or different from one another and each represent a hydrogen atom or a C1-C18 monovalent hydrocarbon group, and h represents a number whose average value is 1 to 4; R.sup.1002 represents R.sup.1001, a hydrogen atom, or a C1-C18 monovalent hydrocarbon group; R.sup.1003 represents R.sup.1001, R.sup.1002, a hydrogen atom, or the group: —[O(R.sup.1009O).sub.j].sub.0.5— wherein R.sup.1009 represents a C1-C18 alkylene group, and j represents an integer of 1 to 4; R.sup.1004 represents a C1-C18 divalent hydrocarbon group; R.sup.1005 represents a C1-C18 monovalent hydrocarbon group; and x, y, and Z are numbers satisfying the following relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, and 0≦z≦1.

A motorcycle tire includes a tread portion, a carcass, a breaker layer disposed outside the carcass with cords oriented at an angle equal to or more than 15 degrees with respect to a tire equator, and a tread rubber disposed outside the breaker layer so as to form a band-less structure in which the tread rubber is arranged so as to be directly in contact with the breaker layer. The tread rubber includes a cap rubber layer forming a ground contacting surface of the tread portion, and a base rubber layer disposed inside the cap rubber layer and having complex modulus greater than that of the cap rubber layer. The base rubber layer extends between a pair of outermost ends thereof so as to across the tire equator, and a thickness of the base rubber layer at the tire equator is greater than that of the outermost ends.

The present invention provides a pneumatic tire with well improved fuel economy, rubber tensile strength, and abrasion resistance. The present invention relates to a pneumatic tire formed from a rubber composition, the rubber composition containing: a hydrogenated copolymer obtained by copolymerization of an aromatic vinyl compound and a conjugated diene compound, the hydrogenated copolymer having a degree of hydrogenation of the conjugated diene units of 75 mol % or more; silica; and a silane coupling agent 1 containing a carbonylthio group (—S—C(═O)—) but no mercapto group (—SH) and/or a silane coupling agent 2 containing a mercapto group (—SH), the rubber composition containing, per 100% by mass of a rubber component, 75% by mass or more of the hydrogenated copolymer.

A pneumatic tire comprises a carcass layer, a belt layer radially outward of the carcass layer, and a tread rubber radially outward of the belt layer. The belt layer includes an angle belt having a belt angle ≥45° and ≤70° in absolute values, a pair of cross belts having belt angles of ≥10° and ≤45° in absolute values and having belt angles of mutually opposite signs, and a reinforcing layer having a belt angle within ±5° relative to a circumferential direction. A width Ws of the reinforcing layer and a cross-sectional width Wca of the carcass layer satisfy 0.60≤Ws/Wca≤0.70. The cross belts are radially outward of the large angle belt. The reinforcing layer is radially inward of the pair of cross belts. A width Wb2 of a wider cross belt of the pair and Wca satisfy 0.79≤Wb2/Wca≤0.89.

The pneumatic tire includes: a belt layer, a belt reinforcing layer, a tread portion, sidewall portions, a rim cushion rubber, and an electrically conductive rubber disposed in the rim cushion rubber and includes a first end in contact with a rim and exposed on an outer surface of the rim cushion rubber and a second end in contact with a tire component adjacent to the rim cushion rubber. The electrical resistance value of the electrically conductive rubber and a portion of the tread portion is 1×10.sup.6 Ω.Math.cm or less. The electrical resistance value of the tire component, a coating rubber of the belt layer, and a coating rubber of the belt reinforcing layer is from 1×10.sup.6 Ω.Math.cm to 1×10.sup.8 Ω.Math.cm. The electrical resistance value of the rim cushion rubber and a side rubber of the sidewall portions is 1×10.sup.8 Ω.Math.cm or greater.

Tread of a tire for an agricultural vehicle. The tread (2) comprises a first, median portion (21) having an axial width L.sub.1, at least equal to 0.25 times and at most equal to 0.75 times the axial width L, and second and third, lateral portions (22, 23) that respectively extend axially outwards from the first, median portion (21) as far as an axial end (E, E′) and have respective axial widths (L.sub.2, L.sub.3). Each lug portion (311) that is axially contained in the first, median portion (21) and extends radially inwards, from the contact face (6) as far as a first interface (7), over a radial distance D.sub.1 at least equal to 0.5 times and at most equal to 1 time the radial lug height H, includes a first elastomeric compound. Each lug portion (321) that is axially contained in one of the second or third, lateral portions (22, 23) and extends radially inwards, from the contact face (6) as far as a second interface (8), over a radial distance D.sub.2 at least equal to 0.5 times and at most equal to 1 time the radial lug height H, includes a second elastomeric compound.

A tire with a radial carcass reinforcement, having a crown reinforcement, itself capped radially by a tread connected to two beads by two sidewalls, the tread having at least two layers of blended elastomeric compounds that are radially superposed and have a voids ratio that is lower in the central part than at the axially outer parts. A first layer of blended elastomeric compounds of the tread is made up of a first blended elastomeric compound forming a part extending at least into the region of the equatorial plane and of at least two axially outer parts formed of a second blended elastomeric compound, the first blended elastomeric compound having a macro dispersion Z-value higher than 65 and a maximum tan(δ) value, denoted tan(δ)max, lower than 0.120, and the complex dynamic shear modulus G* 1% at 100° C. of the second blended elastomeric compound having a value at least 10% higher than that of the complex dynamic shear modulus G* 1% at 100° C. of the first blended elastomeric compound.

A tire with a radial carcass reinforcement, having a crown reinforcement, itself capped radially by a tread connected to two beads by two sidewalls, the tread containing at least two layers of blended elastomeric compounds that are radially superposed and have a voids ratio that is lower in the central part than at the axially outer parts. A first layer of blended elastomeric compounds of the tread is made up of a first blended elastomeric compound forming a part extending at least into the region of the equatorial plane and of at least two axially outer parts formed of a second blended elastomeric compound, the first blended elastomeric compound having a macro dispersion Z-value higher than 65 and a maximum tan(δ) value, denoted tan(δ)max, lower than 0.150, and the elongation at break in a tearability test of the second blended elastomeric compound at 100° C. having a value at least 10% higher than that of the elongation at break of the first blended elastomeric compound in a tearability test at 100° C.

A tread 4 of a tire 2 includes a center region Ta, in an axial direction, including an equator plane, and a pair of shoulder regions Tb located outward of the center region Ta in the axial direction. Each shoulder region Tb includes a base layer 20, a middle layer 22 layered outward of the base layer 20 in a radial direction, and a top layer 24 layered outward of the middle layer 22 in the radial direction. A loss compliance LCt of the top layer 24 is set to be higher than a loss compliance LCm of the middle layer 22. The loss compliance LCm of the middle layer 22 is set to be higher than a loss compliance LCb of the base layer. A breaking energy Et of the top layer 24 is set to be less than a breaking energy Em of the middle layer 22.