Disclosed herein is a rubber composition comprising: a) a blocked mercaptosilane of a defined structure, wherein the blocking group contains an unsaturated heteroatom or carbon chemically bound directly to sulfur via a single bond and, optionally, may be substituted with one or more carboxylate ester or carboxylic acid functional groups; b) an organic polymer; c) a filler; and d) a deblocking agent.