There is info on the air bags in the big package of manuals and instructions you should have received with your unit. I usually run 50 -60 psi. You can adjust air pressures different side to side to level the coach if your loading has one side different than the other. However that is rare and maybe the cargo should be moved around first to balance things.
I believe the maximum is 100 psi with a minimum of 5-10 psi. Also there are cautions, one of them being to deflate the bags fully to prevent damage if you lift the coach by the frame to change a rear tire or lift a rear tire via the Big Foot jacks.