It has been discovered that the use of a plasticizer, an ester of a cyclohexanepolycarboxylic acid, especially a 1,2-cyclohexanedicarboxylic acid ester, that is environmentally non-toxic, can replace environmentally unfriendly phthalate plasticizers, such as dioctyl phthalates used in vulcanizable rubber compositions, especially for tires, on a one to one weight basis (phr) without sacrificing beneficial rubber properties.