Tom -

I put your tire sizes into both sights; Tirerack and Discount Tire. Both have different brands available. I filtered high performance, Z rated, all season.

You have lot's of choices. Some brands I've never heard of. Some brands that I know make a good tire, and some brands that I know make shity tires. The tires I'd be looking at in order of price, (with mileage rating if shown), are:

Michelin PS A/S Plus - $714 (45,000 mile warranty)
Bridgestone Potenza RE 760 Sport - $630
Yokahama Advan S.4 - $598
BFG G-force Super Sport - $550 (35,000 mile warranty)
Continental DWS - $536 (50,000 mile warranty)
Yokahama Avid - $510 (45,000 mile warranty)
Nitto Invo - $486
Dunlop SP - $482

I do not know a whole lot about these tires through personal experience. I do know that the Z06 and ZR1 guys really like the Nitto Invo for all around 'all season' performance. They also mention Michelin a lot. They do not mention the Mich AS much, as they tend to prefer the regular PS2 for the track and the AS does not have a lot of size options for the Z's. I have never used Continental, but if JohnK likes them, I'm certain they will be good tires. I, like Adrian, have had good luck with Yoko's on trucks, but I have no idea if their car tires are any good. I have always liked BFG's, on either car or truck. Great tire, usually great value. I wouldn't buy GY or Firestone tires for my car, period. I've had too much bad luck with both over the years. Dunlop makes great tires. Don't let the price fool you. Their drag tires are all over the place. I've not used Pirelli before, but some people like them. They've always been overly expenive (the most usually).

If you would like, I can ask a question on the Z06 forum about this. Most, if not all of them, have a few other cars in their stable.