I just wanted to add to this thread. I read this thread before I got my promaster, and made up my mind I wanted the larger BFG all terrains in the 245 size. I have a 1 ton long wheel base high roof. I live in minnesota and the stock nexens, or whatever were terrible, ,like driving pure summer tires when it snowed.
With my 245 BFGs I can go down the highway with confidence. Just got back from a 3000 mile road trip from MN to Idaho with no issues, snowed the whole time. I know its not the tire size that helps out so much as the tires, but 245s do fit. There is only about 1/2 inch of clearance in the rear, but I doubt I will ever max out the cargo weight of my Promaster to test the clearance when loaded. Having said that, I do plan to modify the rear fender area if I decide to pull a trailer, because they do look like they would rub eventually.
BFG!