With the original staggered setup, the wheels can't be rotated to even out tire wear. This is a big minus when doing circuit racing, as the front and rear tires wear quite differently. This problem is solved by mounting the same rim and tire dimensions front and rear - a square setup. The wider front tires improves the front end grip, and as a consequence changes the chassis balance from mild understeer to mild oversteer.
I managed to source a set of C5 Z06 18x10.5" replica wheels with 315/35-R18 Hoosier A6 tires. It will be interesting to see how the A6s perform on circuit racing, as they are designed for short autocross sessions generating less heat.
Sticky tires like these will not work with the stock suspension rubber bushings. Even if you adjust maximum negative camber, the rubber will deflect too much under load and screw up the alignment. End result is that the sticky tires can wear out in short time, especially the outer shoulder.
To give the tires a chance to survive I'm installing poly bushings and changing to more aggressive suspension geometry settings.