What is the largest tire that will fit a 1984 chevy 4x4 fullsize stock?

Answer 1

33/12.5R15 or 33/12/5R16 this is about the max without doing any body modes

Answer 2

with 3 leaves up front you can fit 33x12.5" but will rub on dips and turns, i had to trim my fender bottoms on my stock 77 k-10, i eventually swapped 31x10.50 on it

if you have only 2 leaves up front as do many of these trucks then you most likely will not be able to run 33" without even more rubbing, denting of the fenders