Can answer part of your question. Some Z06 guys are running 315.35.17 BFGs mounted on the 9.5x17 Z06 wheels. And they do quite well with no issues reported.
I run 315.35.17 BFGs Comp TA DRs mounted on 12"x17" CCW wheels. And they give consistent low 1.7X 60' and an occasional mid 1.6X. But I haven't seen any comparo between that tire and the newer 315.30.18.
Once source of BFG DRs (I've used) is
http://www.tirerack.com which is, I beleive, a sponsor of the Forum.
Ranger
[Modified by Ranger, 9:55 AM 5/13/2004]