My class A liked 115 PSI
But there are ways to tell... One is to use a powder Flower Chalk both good
Dust the road in front of the tire and note the tracks
FULL width even pressure.... GOOD
edges not well pressed. Lower pressure
Center not pressed.. increase
Or chalk the tire drive a bit and note where the chalk is worn off
Center not worn more pressure. edges less. all evenly worn excellent.
But scaling is the best
Though I like to do every wheel separate and set accordingly.
Many do the axle/2 method. both seem to work.
ONE fact.. You will not wear the tread out...
Why is inflation important?
Too low the side walls flex generating heat and KBOOM you also have less control (Spin outs are easier to do), Trailers can sway more.
Too high and you have less control over the vehicle.