how big on a '75 c20 with no lift

[75chevy]

Right now I've got a '75 c20 with no lift running 15x8 in the front and 15x10 rims in the back with 32" or 33" goodyear's, I think that's the correct sizes.
So how big of a tire do you think I can get away with?
Thanks

[Sano]

usually on a 4wd you want to run the same width of wheel all the way around, but I think stock a 4wd can squeeze some 33x12.50's on it but you might have some rubbing issues. I know 32's fit without problem and I think the 33's might only rub on bumps or something. Your best bet is to take out the measuring tape.