The 6.50 x 16 size tire was a very common application on the older pickups when they were in common usage.. I believe that the commercials could be ordered with the 6.50 tires, and/or the dealers would upgrade the tire size for an additional sum..
Remembering back to 1940: I can remember my father purchasing a new '40 Chevy pickup.. The price of the truck was $25.00 plus my dads '39.. Dad got the salesman to agree to putting 6.50 tires on the new truck, because he had that size on the '39.
A word of caution... The over size tires had a tendency to break the rims at the bead line. My dad had it happen many times.. He finally switched to the "artillery" type of wheels, which are heavy duty wheels on his pickups...
Of course, most restored pickups will most likely never be used to carry heavy loads like they were expected to carry when they were used as work trucks, so the broken rim issue may not be a problem...