Steve, A6's are not that much softer than R's. Almost every T1-3 races on A's at the nationals not just the runoffs. 3700lb Vipers, 3550 lb Corvettes run them in the longer races at nationals without a problem. I have seen up to 230 miles on A6's with good tire management. Something as light as a 240z on 225/45/15's will last a good long time.

matt