Unless someone wants to correct me. Their catalog in the back under tire pressure says to inflate to at least 35lbs. Most their catalog recommendations say 40-44lbs max.
The companies that specialize in whitewall tires tend to stick with higher tire pressures to protect the whitewall. Used to be running a lower tire pressure could result in a split whitewall. I think the tire pressure for the whites on my 40 from Diamond Back is recommended at 35.
I have two sets of 750-16 auburn deluxe on rears and running them at 36 lbs. Not sure I’d want to run any more as my rear is pretty light.
Let your tires talk to you. Get a tread depth gauge and keep track of it. You'll be able to find right setting within a few hundred miles. When long wearing Michelin radials tires became a big thing in the 60s I knew a guy who measured his tread depth every month and adjusted air pressure accordingly. He got over 50,000 miles out of those tires
I’m running the 7:00R -16 auburn diamondback on 1935 ford wire rims with radial tubes and I run 36 psi in them cold, seems to work well for me on my 1936 ford 1/2 ton pickup
I had 32 pounds in my front auburns on my raodster, to stiff. Rides better with 20-25 but harder to steer at low speeds. I have auburns all the way around on my PU, I have 30 in back and 25 in front last time I checked.
I am running 30 all round on my 2060 lb RPU and 35 on my 62 Studebaker Lark Wagon. Both seem to ride and handle well Warren
You could "chalk" the tires and that will tell you a lot about your tire size vs car weight. Sports car guys do this to optimize tire pressure for a given track. Set the tire at the max pressure that is shown on the sidewall. Draw a stripe of chalk an inch or two wide across the tread and extending a bit onto the sidewalls. Drive the car for a few blocks and around a few corners. If the chalk is mainly worn off the center, the pressure is too high. Drop the pressure a bit and repeat the process until you show even wear across the tread face and that ought to put you close to the sweet spot. Once you find that, I would add a couple pounds of air for insurance. A couple points to consider.... A tire that has been driven 5 miles will gain 2-3 lbs of pressure due to heat, so I would not start on cold tires. Try for fairly normal weather, too. Not the hottest nor coldest days. A bias ply tire will probably show more conclusively in this test than radials because of stiffer sidewalls and construction. Radials flex more. You may find that the front tires want a bit more air than the rear tires. Many cars are nose heavy and they have the steering duties along with more of the braking. Especially true if running a staggered set of tire sizes. If you load more weight in the car for a road trip, etc, you will want to run more pressure to compensate. You want really dry roads, etc to try this on. The one area that I am uncertain on is the whitewalls and what may cause them damage. Higher pressure is likely going to keep them out of trouble. The manufacturer may have customer service reps that could be helpful with more info.
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