Weight is the factor. Without knowing the weights you can't set the correct pressure. Weighing each wheel position, single or dual, is best. Next best is by axle which can be done a CAT truck scale. Then set pressure based on the Michelin tire chart.
The folks that post their pressures are usually under the max pressures, typically 15-20 lbs less.
Gary 2017 Dutch Star 4369 Spartan
HWH Active Air Centramatic wheel balancers
Box Elder, SD and the road