biggest tires on a 15x8 corvette rallye wheel?

Hey guys I have a '68 Camaro, I was wondering what the largest tire was that I could put on my rallye wheels in the rear. I have 245 60r15 on there now and I want to go bigger. I'm pretty sure 275 60's would fit. What about 275 50's? or 295 50's? Are 275 50's too low profile or would they be about equal to my 245's in height? Any help would be appreciated.

i have 285 60's on my 80... so it should fit.. i know a 275 would

On my old 68 Z28, I ran 275/60's on 15x8 rally wheels in the back, and 235/60 on the front, also on 8's. The car was lowered an inch or so, and they fit fine.