Abstract: A rubber composition for use in tire having good reinforcing properties and fatigue properties and an improved heat build-up is disclosed, which comprises 30 to 60 parts by weight, based on 100 parts by weight of rubber, of a carbon black having a nitrogen adsorption value (N.sub.2 SA) of 35 to 105 m.sup.2 /g, a DBP absorption value of 140 to 200 ml/100 g, a 24M4DBP absorption value of 60 to 120 ml/100 g and a .DELTA.DBP of 50 to 110 ml/100 g defined by .DELTA.DBP=DBP absorption value-24M4DBP absorption value.

Abstract: A pneumatic tire comprising an improved tread is disclosed. The tread is composed of a rubber composition comprising 10-120 parts by weight of carbon black having an iodine adsorption number of not less than 36 mg/g and a dibutyl phthalate adsorption number of not less than 60 ml/100 g and 0.4-5 parts by weight of a vulcanizing agent based on 100 parts by weight of rubber content consisting of 40-100 parts by weight of styrene-butadiene copolymer rubber (hereinafter referred to as SBR-A) and 0-60 parts by weight of at least one diene rubber other than SBR-A; said SBR-A having a content of bound styrene (S) of 10-30 wt % and a content of 1,2-bond in butadiene portion (V) of 40-70 wt %, which are within a range of 65.ltoreq.1.7S+V.ltoreq.

Abstract: A pneumatic tire having a tread is disclosed, which comprises using in said tread a rubber composition containing 10 to 120 parts by weight of carbon black and 0.

Abstract: A pneumatic tire having a tread is disclosed, which comprises using in said tread a rubber composition containing 10 to 120 parts by weight of carbon black and 0.

Abstract: Organic micro-fiber reinforced rubber compositions having high elastic modulus, excellent crack growth resistance, impact cut resistance and rebound resilience and a small swell value are prepared by incorporating 10-100 parts by weight of carbon black, 3-30 parts by weight of organic micro-fibers based on 100 parts by weight of at least one rubber selected from a group consisting of natural rubber, synthetic polyisoprene rubber, butyl rubber, halogenated butyl rubber, polybutadiene rubber, styrene-butadiene copolymeric rubber, ethylene-propylene-diene ternary copolymeric rubber and acrylonitrile-butadiene copolymeric rubber, said micro-organic staple fibers being lower than 30.degree. C. or higher than 120.degree. C. in glass transition temperature of amorphous portion and higher than 160.degree. C. in melting point of crystal portion, and having an average length of the micro-fibers of 0.8-30 .mu.m, an average diameter of the micro-fibers of 0.02-0.8 .mu.