Rubbers of the substrate include copolymers of the above-noted conjugated diene monomers with one or more vinyl substituted aromatic monomers containing from 8 to 12 carbon atoms such as styrene, alpha-methyl styrene, t-butyl styrene, or a vinyl compound such as acrylonitrile, vinylpyridine, acrylic acid, methacrylic acid, alkyl acrylate, and alkyl methacrylate.