1967 belvedere rear wheel size?

I know this has probably been posted a million times before...but here goes. What is the biggest fattest wheel and tire I can put on my 1967 belvedere with stock wheel wells? I would like to use a drag radial for a tire. Thanks in advance. John

google search is your friend. http://www.google.com/cse?cx=partner-pub...&gsc.page=1

255's by 60 by 14 was the widest I could install without modifying wheel backspace....275's with a mod backspace but they didn't look much different than the 255's

Rims-wise, I had a set of lil red 15x8's on rear of a 67 satellite for a while. I can't recall what tires were on there, but IIRC the backspacing is 4 1/2" on them.