Plastified novolaks as additive to rubber mixtures

The invention relates to a method of use of plastified novolaks as additive to rubber mixtures, leading to higher tear propagation resistance and also to lower compression set in the vulcanizates produced therefrom. Use, as modifier resin for rubber mixtures, of novolaks ABC plastified with terpene-type olefinically unsaturated natural substances C, where the ratio of the molar amount of the phenol or phenol derivative B and the molar amount of the natural substance C in the modified novolak is from 1:6 to 6:1, process for increasing the tear propagation resistance and reducing the compression set of rubber vulcanizates by adding these modifier resins to rubber mixtures, and components molded from vulcanizates thus prepared.