Dont listen to what the tire place says, there just trying to sell you some fancy rims. I went to 3 big name tire places before i found one that would mount my 315-75 16 (which is around a 35x12.5) on my 7 inch rims. They made me sign a waiver but they said that they would work fine. They worked great and looked great. i put 30,000 miles on them that way and that was on my huge excursion that pulled many a big trailers.
Stock wheels are 7" wide i believe so 11.5" wire tires would be great!