BFG's tend to run wide.
Bear in mind that all of the measurements on tirerack are taken with the tire mounted on a wheel of "measuring rim width." If you're looking at a 275 tire that they measured on a 10" rim, don't expect to put it on a 9" rim and get the same dimensions.
Right. So a 275 tire on a 8.5" wheel is not going to be as wide as a 275 on a 10" wheel, correct? I'm probably gong to upgrade to 255/45/18's on my stock 8.5" Bullitt wheels, so their measurements should be pretty accurate.