The present disclosure provides reinforcing filler-containing rubber compositions suitable for use in tires, and particularly in tire treads. These rubber compositions comprise a metal carboxylate. The metal carboxylate provides improved processability to the rubber compositions in the form of a reduced Mooney viscosity. In certain exemplary embodiments, these rubber compositions containing the metal carboxylate also have an enhanced elastic modulus (also referred to as the G′). Further, in certain of the enhanced elastic modulus embodiments, the rubber compositions containing the metal carboxylate also have decreased hysteresis loss.