Abstract: A method of continuously polymerizing a conjugated diene monomer and a vinyl aromatic hydrocarbon monomer in a hydrocarbon solvent by using an organolithium initiator, adding to the polymerization mixture a tin compound and again adding a tin compound after the polymerization mixture has been withdrawn from the polymerization vessel. The resulting diene polymers possess a significantly reduced Payne Effect and a substantial reduction (over 10%) in tan delta at 50° C. which results in tires having decreased hysteresis loss, excellent wear resistance and rolling resistance and good wet skid resistance.