Abstract: The invention pertains to a sulfur cross-linkable unvulcanized rubber mixture for the manufacture of treads, in particular for winter tires. The rubber mixture contains polyisoprene, polybutadiene and styrene-butadiene copolymer as well as further fillers and additives. In order to prepare vehicle pneumatic tires which exhibit excellent traction on ice and snow while at least maintaining their wet-gripping ability, the rubber mixture preferably contains, relative to 100 parts of total rubber, 20-100 parts by weight cis-1,4 polyisoprene; 0-65 parts by weight polybutadiene with a cis content of greater than about 90 mole %; and 0-65 parts by weight solution-polymerized styrene-butadiene copolymer; as well as 65-120 parts by weight silicic acid.

Abstract: A rubber composition for tire treads includes a rubber mixture and a fiber mixture of cellulose fibers and keratin fibers in a weight ratio of 1:5 to 5:1 mixed into the rubber mixture. The fiber mixture is present in the rubber composition in 2 to 25 parts by weight per 100 parts by weight of rubber. The keratin fibers are preferably wool fibers, animal hair, and animal bristles and the cellulose fibers are preferably cotton fibers and coco fibers.