I recently purchased a 78 w300 in good shape 360 4sp np203 but the truck had 19.5 rims with 8r19.5 rubber after talking to a few dodge owners and oil field workers who drove simular vehicles they suggested dropping down to 16" rims and tires while my power seams to come up just a bit now my top end speed had dropped dramaticly.Now I know the speed limit was 55 back then what should have been the correct tire size for these trucks?
The truck has monster power and sets high on the 16"rims but the 19.5s looked very good on the truck and the ground clearence was awesome. The truck is,was and has been a winch truck for most of its life complete with rolling tail boards and gin poles. It came with a goose neck trailer and I am planning to move some farm equipement around and hotshot a few loads from time to time and I would like to know more about my new truck.
Any info would be very helpfull ty

 

Not sure what stock size was, but Im running 16.5's (stock steel wheels from an '85). Fits the truck well in my opinion.