A rubber compsn. comprises an S-vulcanizable diene rubber, an S- vulcanizing agent, an organic vulcanization accelerator, and a premature vulcanization inhibitor of formula (I) in which R' is H or -SR; R is C1-12 alkyl or alkyl substd. by CN, acetoxy, or C2-5 alkoxycarbonyl, C7-10 aralkyl, C5-8 cycloalkyl, phenyl opt. substd. by Cl, C1-5 alkyl or C1-5 alkoxy; and X is H, Cl, C1-5 alkoxy, or C1- 5 alkylthio.
PREVULCANIZATION INHIBITORS