Rubber composition and tire having tread thereof

DETAILED DESCRIPTION What is claimed is: 1.
A tire having a tread of a rubber composition comprised of the product of blending: (A) 100 parts by weight of at least one diene-based elastomer selected from homopolymers of conjugated dienes, copolymers of conjugated dienes and copolymers of conjugated dienes with vinyl aromatic compounds selected from at least one of styrene and alpha-methylstyrene; (B) about 30 to about 110 phr of reinforcing filler composed of (i) a carbon black composite or (ii) about 20 to about 70 phr of said carbon black composite and (a) about 10 to about 40 phr of at least one of additional rubber reinforcing carbon black and precipitated silica; wherein said carbon black composite is composed of an intimate blend of fumed carbon black particles and fumed silica particles; wherein said fumed silica particles of said carbon black composite and said precipitated silica contain silanol groups on the surface thereof; wherein said carbon black particles of said carbon black composite and said additional carbon black contain hydroxyl groups on the surface thereof; wherein said silica particles of said carbon black composite reinforcing filler contain from about 0.
1 to about 10 percent of at least one of aluminum, titanium, zirconium and magnesium entities, based upon the silicon content of the silica; and wherein the silicon to carbon ratio of said carbon black composite is in a range of about 0.
1/1 to about 0.
9/1, and (C) at least one coupling agent having a moiety reactive with the said silanol groups and said hydroxyl groups and another moiety interactive with at least one of said diene-based elastomers; said rubber composition is prepared by (a) thermomechanically working and mixing, in at least two sequential mixing steps, a mixture comprised of the said diene-based elastomer, carbon black composite, and optionally the said additional carbon black and/or precipitated silica, all in the absence of curatives (i) to a maximum temperature in a range of about 160.
degree.
C