When/how/why max tire pressures raised from 35 PSI to 44 PSI?

This is another discussion we can find on many forums. If you did the math on sidewalls and knew the weight of your vehicle,a little math and you would have the pressure the tires could carry the car.
Door jamb for factory rated tires.
Deviate from factory size is a matter of preference. So is tire psi.
My power wagon runs 17 in the back and 22 in the front with a plow. 35x12.50-15 tires. Any more than that and tire print is the 2 center treads touching the road. At 45 psi this rig wont move on slick roads, as there isnt much of a contact pattern.

My wife’s pt cruiser, you cant tell any difference between 20 psi and 40 by looking at them. To me they always look flat.