Diameter of BFG 275/70 R18 IS 33.2 inches. Stock are 32.1. difference is 1.1 inches. Divide that by 2 since only half the wheel extend above the mounting lug nuts. Tire will be just a little over a half inch higher.
@fergthulhu That's just a small part of it. Ford is now allocating to dealerships based upon their (past) sales rather than by the number of reservations that a dealership has gained from buyers. Therefore, a dealership with small prior year sales and with lots of reservations just got screwed...