I have an 80 and ran Dunlop SP4s 234x60. These were all right. Not great and the small size didn't look good. I could not find any high permormance 15" in the right size so I upgraded to 16" with 86 C4 wheels and VetteBrakes adapeters. I installed Yokohama AVS intermediates 245x16 fronts and 255x16 rears. These balanced well (smooth all the way to 110) and handle very well, although some of the handling improvement is sue to the full VetteBrakes suspension front and rear) I also have a 1992 Mazda RX7 Turbo II with Eibach springs, Koni shocks, and Racing Beat swaybars and goodies and Goodyear 225x16 Eagles and the Vette is faster in the twisties with the difference improving as the speeds increase although the MAzda is ultimately faster (the Vette needs more engine which it will get)