15x7 4 1/8 bs- largest tires?

255/70/15 BF Goodrich tire on a 7 1/4 BS rallye wheel on a 1969 Dart. I had to shim/ move the leaf spring back a 1/4 inch to clear the front quarter. mancini sells the plates, used for reinforcement on the super stock cars, or make your own.

I have a question as well. Where to get street/slick tires with the same dimensions as this tire profile to run at the track? I have been having a hard time finding anything, other than slicks.