There should be a sticky that doesn't allow one to ask these questions until their rig is weighed...I cannot believe how many people do not know the weights of their equipment.
PSI is based on axle weights...period...with a small buffer if you wish. It's a fact that almost ALL blowouts are the result of underinflation of the tires. All tire manufacturers advise to use their tire inflation tables NOT what's printed on the sidewall.....it's certainly not rocket science....weigh your rig, consult the inflation tables, air up the tires and enjoy the trip.....:).....Dennis