Just want to thank everyone for the responses because they stimulated me to do some more research. I'm not comfortable with the 11" width of the 285 75R 16, plus they would push the limits of the 16x7 rims size and I'm not sure if they would fit into the rear wheel well of the panel.
The suggested LT 7.50x16 radial would be a great choice, but I'm not finding any except in trailer tires. Same thing with the comparable 255 85R 16 only being available in trailer tires or 'extreme' off road.
I decided to go with 235 85R 16's. They are 31.7" tall, 9" wide and are a good fit for the 16x7 rims. Just a bit taller and wider than the original 17.5" bias plies currently on the truck, so a nice match. PepBoys has a sale going on with their own label tires in this size for $85 per tire. It has a highway tread and a 60,000 mile warranty...more miles than this truck will ever see!
https://www.pepboys.com/tires/details/Definity/Dakota%2520HT/9484450/00735
I mentioned that I have 8R19.5's on my '57 3600. They look good and give me the better top end with my 4.10 gears, but they really push the limits of the wheel wells...and they are a real pain to take off and put back on. I'm not sure if a tire that tall would work on the panel truck.
Thanks again for your help,
Matt
