I currently have a set of Eagle 16x10 and have 285/75r16's mounted on them. Before I did it I contacted BFG and asked their rep and he said a half inch of float on either side is allowable. In the BFG catalog, or any other tire manufacturer, if you look up your tire size it tells maximum allowable mounting size. For the 285's it was 9.5 inches so 10 would seat ok. I don't crawl in my truck so I can't vouch for low pressure running. Lowest I have done is 12 PSI and no problems. When you have the tires mounted they will just have to pull up on the tire to help seat the top bead.
