i believe 235 75 on 15s or 235/70 on 16s.
also going much wider will effect lock, oh and
of course dont forget your insurer.
the more aggressive mud treads will be taller
than their at/ht equivalents.
31x10x15 will go but foul front mud flaps but
easily removed. after that looking at 32"s with
bit of panel beating to front arches or 33s with
some lifting, either body or suspension or both
for 35s.
for front lift, torsion bars can be wound up which
helps raise front, often restoring sagging with age.
beyond this they can be reindexed which is slightly
bigger job. rear lift is easier with lwb springs on swb
vehicles or new taller springs. typically around 2
inches. general opinion is 2 inch body lift reasonably
straight forward.