Abstract: A rubber composition for coating steel cords, comprising a raw material rubber and, compounded therein, a methylolmelamine derivative and a product of a reaction of a cobalt salt of an organic acid with a metaboric acid ester, and a rubber product reinforced with rubber-coated steel cords comprising steel cords coated with the rubber composition.

Abstract: A rubber composition for tire treads which comprises 100 parts by weight of a rubber component comprising 10 to 100 parts by weight of a styrene-butadiene copolymer rubber produced by a solution polymerization and 90 to 0 parts by weight of at least one of other diene rubbers having a glass transition temperature (Tg) of -60.degree. C. at lowest, and at least 70 parts by weight of a carbon black mixed in the rubber component, the styrene-butadiene copolymer rubber having a styrene content of 45 to 65% by weight, a content of butadiene derived vinyl groups of 20 to 70 parts by weight and a content of a styrene sequence consisting of not less than 8 bonded styrene monomer units of at largest 10% by weight of the above styrene content.

Abstract: Rubber compositions are disclosed for use in the tread portions of automotive tires. A selected class of starting rubbers are combined with specified amounts of a selected type of carbon black having well balanced N.sub.2 SA, 24M4DBP and .DELTA.Dst properties. The use of this carbon black is conductive to enhanced driving stability and other important physical characteristics of the tire.

Abstract: A promoter for bonding between a rubber and a steel cord, which is represented by the following general formula (I): ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 may be the same or different from one another and each represents a monocarboxylic radical bonded to the adjacent Co atom through the oxygen atom which is adjacent to the carbonyl group in said monocarboxylic radical; a rubber composition containing the bonding promoter, and rubber products made from the rubber composition.

Abstract: Rubber compositions for use in tire treads are disclosed which are essentially made up of natural and/or a selected class of polyisoprene rubbers of specified cis contents and a selected class of styrene-butadiene rubbers of specified styrene and 1,2-bond contents. The composition has a unique viscoelasticity curve, exhibiting sufficient wet skid resistance and adequate fuel saving.