rim and wheel size

i own a 64 couple and want to on occasion switch to a more modern looking wheel and tire. i want to know what offsets on the rim i need to know when purchasing new rims. i am thinking a 70 series tire, but do not want the tire to extend beyond the fend well. what would be the max. offsets (outer and inner) thanks..

After grueling research for my 65 coupe I have found little info from wheel manufacturers etc... No one seems to have info for pre 68 corvette aftermarket wheel fitment on the net. Try this past link http://forums.corvetteforum.com/showthread.php?t=1039768 I hope this will get you there for I am not a computer wiz. If you cant find this thread, I'll transcribe some of the wheel tire sizes discussed in the forum. I'm looking at 17" tall x 7" wide American Racing Hopster with 215/50/17 tires with stock suspension.