I have 30x11.5 super swampers and i ran about 7psi when I was in moab, i had 7 inch wide rims. The side wall on my tires are pretty strong, with how much weight a zuk is, you can usualy go pretty low. Just try diff. pressures and find out whats best for you.
Zero psi! I've seen Yankee Tim run a 33" swampers run his zuk with the valve stem cores pulled out. I have run my 31" General Grabber MT's down at 3 psi on a 7" wheel before. Most of the time I them between 5 & 8 psi.