Prevulcanization inhibitors of thio-triazine-amines for rubber

A vulcanizable rubber composition comprising sulfur-vulcanizable diene rubber, sulfur-vulcanizing agent, organic vulcanization accelerating agent and, in an amount effective to inhibit premature vulcanization, a compound of the formula ##STR2## in which R' is hydrogen or --SR, X is hydrogen, chloro, alkoxy of 1-5 carbon atoms, alkylthio of 1-5 carbon atoms, NHR", N(R").sub.2 where R" is R or allyl, NHSR, N(SR).sub.2 or R, and R is alkyl of 1-12 carbon atoms or alkyl substituted by cyano, acetoxy, or alkoxycarbonyl of 2-5 carbon atoms, aralkyl of 7-10 carbon atoms, cycloalkyl of 5-8 carbon atoms, phenyl, or phenyl substituted by chloro, alkyl of 1-5 carbon atoms, of alkoxy of 1-5 carbon atoms.