Rubber compositions

A rubber composition which exhibits improved cut resistance and chipping resistance comprising 1 to 30 parts by weight of at least one resin, based on 100 parts by weight of at least one rubber selected from the group consisting of natural and synthetic diene rubbers, wherein said resin is selected from the group consisting of:

• (1) a hydroxyl group-containing cyclopentadiene resin (R.sub.1) obtained by heat copolymerizing:
• (i) 100 parts by weight of component A, wherein component A is at least one compound selected from a cyclopentadiene ring containing compound represented by the following general formula:
• ##STR3## wherein R is an alkyl group having 1-3 carbon atoms and m is an integer of 0-6, and its Diels-Alder reaction adduct with,
• (ii) 2 to 120 parts by weight of component B, wherein component B is a compound selected from the group consisting of unsaturated alcohols having 3-22 carbon atoms, unsaturated divalent alcohols, hydroxyalkyl acrylates and hydroxyalkyl methacrylates, and
• (2) a resin (R.sub.2) obtained by reacting:
• (i) the hydroxyl group-containing cyclopentadiene resin (R.sub.1) with,
• (ii) component C., wherein component C is a polyisocyanate compound, at an equivalent ratio of isocyanate group in component C to hydroxyl group in resin (R.sub.1) of 0.05-1.5.