A tire for a heavy vehicle of civil engineering type, intended to be fitted onto a rim, is provided. The nominal diameter of the tire is at least equal to 25 inches. The tire comprises a tread having a radial thickness HT at least equal to 30 mm. The tread has a composition based on at least one diene elastomer, a reinforcing filler predominantly comprising a filler at least partially covered with silica, an agent for coupling the filler to the at least one diene elastomer and a crosslinking system. The dispersion of the filler in the elastomeric matrix has a Z score of greater than or equal to 70.

Large tires, the tread of which has a mean volumetric void ratio over the entire tread of greater than 10%, comprise a composition based on at least one diene elastomer, on a vulcanization system and from 0.10 to 1 phr of at least one organic polysulfide.

The present invention relates to a modified conjugated diene-based polymer, a method for preparing the same and a rubber composition including the same, and relates to a modified conjugated diene-based polymer which is prepared by continuous polymerization and has excellent processability, a mooney large relaxation area of 300 MU-s to 1000 MU-s, and narrow molecular weight distribution, and if compounded into a rubber composition, shows improved tensile properties and viscoelasticity properties, particularly, a tan δ value at a high temperature (60° C.) among viscoelasticity properties, and excellent low hysteresis properties and fuel consumption properties, and a rubber composition including the same.

The present disclosure provides a rubber composition and a tire which provide improved overall performance in terms of wet performance and dry performance. The present disclosure relates to a rubber composition, containing at least one polybutadiene rubber and/or at least one styrene-butadiene rubber, having a complex modulus E* that reversibly changes with water, and satisfying the following relationships 1) to 3): 1) Complex modulus E* when water-wet/Complex modulus E* before water-wet×100≤98 wherein E* represents the E* at 23° C. of the rubber composition; 2) 99≤Complex modulus E* after water-wet and dehydrated/Complex modulus E* before water-wet×100≤100 wherein E* represents the E* at 23° C. of the rubber composition; 3) 99≤Volume when water-wet/Volume before water-wet×100≤100 wherein Volume represents the volume at 23° C. of the rubber composition.

Provided is a rubber composition that realizes excellent low heat generating properties while maintaining good steering stability when applied to a tire. The rubber composition of the present disclosure contains a rubber component containing a copolymer having a conjugated diene unit and an aromatic vinyl unit, and a filler, where the copolymer is a modified copolymer having a content of the aromatic vinyl unit of less than 10 mass % and modified with a modifier containing a compound represented by the formula (1).

##STR00001##

A pneumatic tire is formed from a tread rubber composition, which comprises a combination of at least two different solution polymerized styrene-butadiene rubbers (s-SBRs), each extended with oil, and a low Tg traction resin. The low Tg traction resin replaces high Tg traction and the rubber processing oil added during rubber compounding in conventional compounds. The low Tg traction resin is a hydrocarbon resin having a Tg between 100° C. to about 30° C.

Provided are a rubber composition for tires and a pneumatic tire, which are excellent in braking performance on ice and failure properties. The rubber composition for tires includes, per 100 parts by mass of a solid rubber component, 1 to 20 parts by mass of a liquid polybutadiene having a glass transition temperature of −80° C. or less and 1 to 30 parts by mass of vegetable granules having a particle size of 0.1 to 500 μm.

A conjugated diene-based rubber including a polymer block (A) containing isoprene monomer unit as the main component and a polymer block (B) containing 1,3-butadiene monomer unit as the main component, wherein at least one of the polymer block (A) and the polymer block (B) contains a unit of a vinyl compound having a functional group interactive with silica, the polymer block (A) has a weight average molecular weight (Mw) in the range of 1,000 to 30,000, and the entire conjugated diene-based rubber has a weight average molecular weight (Mw) in the range of 50,000 to 5,000,000.

A rubber composition of the present invention contains 100 parts by mass of a rubber component (A) containing 45 to 75% by mass of natural rubber and 25 to 55% by mass of a conjugated diene-based polymer, in which a bonded styrene amount of the conjugated diene compound moieties is 25% or less, 1 to 40 parts by mass of a non-modified conjugated diene-based polymer (B) which has a weight average molecular weight of 5,000 or more but less than 40,000 in terms of polystyrene as measured by GPC and in which a bonded styrene amount of the conjugated diene compound moieties is less than 10% and a bonded vinyl amount of the conjugated diene compound moieties is 20% or more, and a filler (C), in which at least one of the conjugated diene-based polymers contained in the rubber component (A) is a modified conjugated diene-based polymer. With the rubber composition, a tire having further enhanced on-ice performance and having both excellent on-ice performance and excellent abrasion resistance is obtained.

There is provided a rubber composition which can provide a tire having an excellent balance of the breaking properties, the rolling resistance performance (low fuel consumption) and the wet grip performance. The rubber composition includes 100 parts by mass of a diene rubber, and 1 to 100 parts by mass of fine particles (A) having a glass transition point of −70° C. to 0° C. and composed of a polymer comprising constituent units of at least one monofunctional monomer. The fine particles (A) have a crosslinked structure crosslinked by at least one polyfunctional monomer having a polysulfide bond in which at least two successive sulfur atoms are bonded together.