Toyo m/t sand air pressure

[sfgiantsfan9]

Hey guys. Just picked up an 07 h3 this last Saturday and finally have a chance to get awAy to the pismo for to hit the dunes. I'm no rookie on the dunes as I've had many vehicles that I've taken out there but just looking for a little advice from the hummer experts as I am a newb when it comes to the h3. What air pressure would be good for toyo open country m/t's size 35x12.50x20? Just don't want to run off the bead. My last f250 on 35's I ran it at 20psi but that was on a 17 inc rim vs the 20's now. Would 20 be too low for this size tire/wheel and weight of the h3? Thanks from a noob.