It will depend on what you intend to do with the truck- - - - -bigger tires allow it to haul heavier loads. Do you plan to do what it was intended to do- - - -haul maximum loads, or just motor around to car shows with the bed empty? If the truck won't be hauling cargo the way it was designed, virtually anything that will hold air will be sufficient.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!