Let me get this right...you are saying that Ford (and tire company) engineers are all idiots and that they should just put 45psi in the tires and not pay attention to the recommended inflation pressure sticker or the writing on the sidewall of the tire that tells you its specific weight capacity and the pressure that this capacity is valid at?
No, the tire company engineers are the ones that developed the load/inflation tables, through their association, the Tire and Rim Assn(TRA). The TRA develops the numbers, and publishes them in their annual report to members. All the tire company engineers know exactly what the load/inflation tables say. And they agree with them.
But they are complicated, with lots of ifs, ands and buts. So how do you educate the public?
But then the lawyers get involved, and the engineers get overruled by "management" afraid of lawsuits. Some tire companies don't even publish the load/inflation tables. They fall back on the excuse that you should do what the vehicle manufacturer suggests. Then if you want to sue somebody, you can sue Ford, but not Michelin.
The vehicle manufacturer puts only one number on the door sticker, and that number assumes you have loaded the vehicle to the max. So if your door sticker says 55 front and 70 rear, that's only when you are loaded to the GVWR of the vehicle, or in some cases loaded to the front and rear GAWR of the vehicle. When you are loaded to less than GVWR (or GAWRs), you can safely put less air in the tires. How much less? That's what the load/inflation table tells you.
The tire manufacturer cannot print the entire load/inflation table on the sidewall. So they print only the max weight and the PSI needed to have that weight capacity. That's doesn't mean the tire company engineers are idiots. They all know exactly what the load/inflation tables say.
But management assumes all customers are idiots. They hope you will pump up your tires to the max on the sidewall, because too much PSI is safer than not enough. But informed customers know about the load/inflation tables, and use them.
Here is some 'portant poop from Goodyear, which Goodyear reprinted from the TRA annual report. Study it and use it and your truck will ride better and your tires will last longer.
Goodyear Load/Inflation tables
That's a 19-page PDF file. The load/inflation table for the LT285/75R16 is on page 7 of 19 per Adobe Reader. Compare the "Single" line to the table I posted earlier and you'll see I didn't pull those numbers out of my rear end.
Also note that Goodyear's tables only include the tire sizes that Goodyear sells. You won't find huge donuts in those tables, because Goodyear doesn't market huge donuts.
But Toyo does. Look around on the Toyo website, and you'll probably find the load/inflation tables posted by Toyo for the sizes of LT tires they market.
Here are some of the TRA tables from a few years ago:
TRA load/inflation tables
That's a 32-page PDF file, and the load/inflation tables begin on page 21.
By the way, all load/inflation tables for the same size tire will be identical - taken from the same page of the TRA annual report. So if you can find a Goodyear load/inflation for size LT285/75R16, then you know that table will be good for a Michelin or BFGoodrich or Toyo LT tire of the same size.
You homework for tomorrow: My front axle weighs 4,440 pounds and my rear axle weighs 5,180 pounds. My tires are size LT235/85R16E. I tow at 62 MPH going cross-country from Texas to New York and return. What should my tire pressure be on my tow vehicle?
Class dismissed for today.