You asked, so here are my thoughts:
Tire size... The 255/75R17 size you're looking at exists because of the Wrangler Rubicon. I've not seen any yet that have a load range higher than C. I would not put a LR C tire on a 3/4 or 1 ton truck... I would recommend the size I'm running as being a good alternative: 255/80R17.
Tire pressures... First, check your door sticker. Run your front tires at that pressure. On my 2500 GMC, that pressure is 55psi. That was on tiny 245/75R16's, and generally speaking, bigger tires require less pressure to handle the same load as a smaller tire. There is no reason to run more pressure than the sticker recommends unless you have a heavy snow plow or big pipe bumper and winch adding considerable weight to the front axle.
Ideal rear pressures for an empty truck are usually the same or even slightly less than the door sticker suggests for the front tires. (Trucks are often front heavy when empty, and since you're always mostly empty from a weight perspective, this applies to you...) Running the rear tires at higher pressures when empty amplifies any axle hop tendency, reduces traction on any soft surface, creates washboard very quickly on dirt roads, wears the tire out much faster, and makes for a rough ride on back roads.
Your desire to run equal pressures all around is for cars, not trucks. Get over it. For trucks, you run appropriate pressures front and rear for the axle weights. "Compromising" pressures on a truck means running the rear tires at or near max pressure all the time becasue you actually use the truck to haul things regularly, and you're compromising things when empty. There is no need to "compromise" on your truck, as you're not hauling regularly, if ever. There is certainly no reason to run such high pressures on an empty truck, aside from keeping the TPMS light out for the rear axle.
The suggestion in the post above is a very good sanity check. BFG also publishes load/pressure charts IIRC. Ford may be erring to the high side, after their Firestone debacle from years gone by, so a sanity check may show that the door sticker is even higher than it needs to be...
You can get axle weights at any gravel pit, grain depot, or highway weigh station when it's not busy. Or you can probably look them up for your truck and just add several hundred pounds to the rear axle.
As usual, YMMV, but probably not by much...
Thanks so much! I will be getting my fully loaded rig weighed which I have been putting off as well. My camper and upgrades are way under the GVWR, but it will be good to know exactly how much.
Great points all around on measuring and optimizing the tire pressure based on the weight distribution. I will test and iterate starting with the manufacturer door specs until I find the right combinations.
Yeah, that particular tire has a load rating that is way too low at 2400 lbs. They don’t make a Cooper STT Pro in 255/80R17, but they do make a 265/70R17 with a 3195 lb load rating. I have to see if that would fit on the stock wheels for me.
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