I'm running Vintique Rallyes & BFG TA's, 245/60/15s on 15x7 rims on front, 275/60/15s on 15x8 rims on back. No clearance issues on mine, but my car may be running heavier springs in back installed by the original owner. But based on many comments in the sticky Ebody Tire Combos post at the top of this section this is a fairly common tire/rim size on these cars. Anything larger than 275's and you'll probably have to go the offset spring route. Read through the Tire Combos post and I think you'll get a good feel for what fits and what doesn't.
Later, Jim