All tires, yes ALL tires {Motorhome, truck, Trailer, motorcycle etc.}, should be inflated to the proper psi based upon two things:
The the manufacturers load/psi tables and the actual load they are carrying. Door jamb labels and max psi stamped on the sidewall are worse than useless if they leave you over or under inflated... and often they do exactly that. Every rig is different and needs to be weighed and the psi set accordingly. "Max psi" is just that and not necessaarily what you should be running.
Also, all tires should be balanced.
:C