[68 Fastback]

For those of us who do not have fender wells how sticky a tire can you go without busting the fiberglass, You know those nasty little star bust? I know, I know you can add additional coatings and other stuff. So lets not consider that at this time. I currently have Goodyear F1 (old and hard) They are listed at 280 AAA. Has anyone used Nitto NT05 (200 AAA) and not slung a rock?