Vulcanizable rubber compositions scorch inhibited by 2-(thioamino)-4,6-diamino-1,3,5-triazines

A 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, R.sub.1 and R.sub.2 independently are C.sub.1 -C.sub.12 alkyl, C.sub.5 -C.sub.12 cycloalkyl, C.sub.7 -C.sub.10 aralkyl, phenyl, or mono- or di-substituted phenyl wherein the substituents are C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, or C.sub.1 -C.sub.6 alkylthio, or R.sub.1 is hydrogen.