Abstract: High-performance tires comprising treads made of elastomer compositions comprising (A) ultra high molecular weight copolymer compositions of 1,3-conjugated dienes and aromatic vinyl compounds having a weight average molecular weight of greater than about 1,000,000; (B) extender oil; and (C) carbon black are described. The ultra high molecular weight copolymer compositions which are also characterized as having an intrinsic viscosity in tetrahydrofuran of at least about 4.0 may be obtained by a process which comprises polymerizing a 1,3-conjugated diene and a vinyl aromatic compound in a hydrocarbon solvent in the presence of a trimetalated 1-alkyne catalyst which comprises the reaction product of a 1-alkyne containing at least 4 carbon atoms, an organo metallic compound R.sup.o M and a 1,3-conjugated diene wherein R.sup.o is a hydrocarbyl group, M is an alkali metal, the mole ratio of R.sup.o M to 1-alkyne is about 3:1 and the mole ratio of conjugated diene to 1-alkyne is from about 2:1 to about 30:1.