A tire comprised of two spaced apart individual rubber sidewalls and a circumferential tread of a lug and groove configuration including tread lugs designed to be ground contacting, wherein a portion of said sidewalls is joined at the periphery of said tread with a plurality of tread grooves;
- wherein said sidewall portions and said plurality of tread grooves are exclusive of carbon black and therefore of a non-black color;
- and wherein said the outer surface of said tread lugs designed to be ground-contacting contain carbon black reinforcement and are therefore of a black color;
- and wherein said sidewall portions and said joined tread grooves contain a particulate, synthetic amorphous silica reinforcement;
- wherein said non-black colored sidewall portions and joined non-black colored tread grooves are of a non-black colored rubber composition which comprises, based upon parts by weight per 100 parts by weight elastomer(s), (phr):
- (A) 100 phr of elastomer comprised of
- (1) about 5 to about 80 phr of a halogenated copolymer of isobutylene and p-methyl styrene, wherein said halogen is selected from bromine or iodine,
- (2) about 20 to about 95 phr of at least one diene-based elastomer and
- (B) about 25 to about 100 phr of particulate reinforcing filler comprised of synthetic amorphous silica aggregates, wherein said silica aggregates contain hydroxyl groups on their surface;
- and
- (C) about 0.5 to about 25 phr of an organo phosphite selected from at least one of monophosphites selected from formula (I) and diphosphites selected from formula (II) and diisodecyl pentearythritol diphosphite, distearyl pentaerythritol diphosphite and pentearythritol diphosphite:
- wherein each R4 radical is independently selected from alkyl radicals and phenyl radicals and alkyl substituted phenyl radicals;
- wherein said R4 alkyl radicals have from 1 to 18 carbon atoms, wherein R5 is a phenyl radical;
- and wherein R6 is selected from alkyl radicals having from 2 to 8 carbon atoms;
- wherein said organo phosphite is provided by one or more of the following:
- (a) by mixing said organo phosphite with said elastomer(s) and said synthetic silica in an internal rubber mixer,
- (b) by pre-reacting said halogenated copolymer of isobutylene and p-methyl styrene with said organo phosphite prior to blending said reinforcing filler therewith,
- (c) by pre-reacting said organo phosphite with an aqueous dispersion of colloidal silica particles from which a precipitated silica is recovered to form an organo phosphite/silica composite thereof,
- (d) by mixing said organo phosphite with said elastomer(s) and said synthetic silica, according to any of said steps (a), (b) or (c), wherein said synthetic silica includes pre-hydrophobated silica aggregates which have been pre-hydrophobated prior to mixing with said elastomers with an alkylsilane of formula (III),
- (e) by mixing said organo phosphite with said elastomer(s) and an alkylsilane of the said Formula (III) with said elastomer(s) and said synthetic silica, and
- (f) by pre-reacting said organo phosphite and said alkylsilane of Formula (III), and optionally an organomercaptosilane of the general formula (IV), with
- (i) said aggregates of synthetic precipitated silica or
- (ii) an aqueous dispersion of colloidal silica particles from which a precipitated silica is recovered to form a silica composite thereof;
- wherein said alkylsilane of the general Formula (III) is represented by
- Xn—Si—R4-n (III)
- wherein R is an alkyl radical having from one to 18 carbon atoms, n is a value of from 1 to 3 and X is a radical selected from chlorine, bromine and alkoxy radical as (OR1)—, wherein R1 is an alkyl radical selected from methyl and ethyl radicals, and where said organomercaptosilane is of the general formula (IV):
- (X)n(R2O)3-n—Si—R3—SH (IV)
- wherein X is a radical selected from chlorine, bromine, and alkyl radicals having from one to 16 carbon atoms;
- wherein R2 is an alkyl radical having from one to 16 carbon atoms and R3 is an alkylene radical having from one to 16 carbon atoms;
- and n is a value from zero to 3.