A wax-polymer compound includes (a) a polymer component that is a polymerized unsaturated monomer, optionally copolymerized with a vinyl-aromatic monomer, and (b) a halogenated hydrocarbon wax component. The polymer component is grafted to the halogenated hydrocarbon wax component, and the wax-polymer compound has a number average molecular weight of about 1,000 to about 100,000, A method of making the wax-polymer compound and a coated silica particle are also disclosed. A rubber composition includes a rubber elastomer comprising a polymerized unsaturated monomer and optionally a polymerized vinyl-aromatic monomer, the elastomer having a number average molecular weight of about 100,000 to about 1,000,000. It further includes a filler in an amount of about 5 to about 200 phr, the filler comprising carbon black, silica, or both; and a wax-polymer additive.