I need to buy some new tires for my newly purchased 2012 Ecoboost SCrew 4x4 with 6.5' bed and 3.55 gears. I need some input on what effect larger tires will have on this truck with the Eboos engine. Staying with stock 20" rims and thinking of buying 275/65/20 all terrains. Will the 34" tires hurt the power much? I realize the mpg's will suffer a bit, but truck really needs some taller tires due to it's length (IMO). Looking at either BFG AT KO's or Cooper Discoverer ST Maxx. Some real life experiences would be appreciated. Thanks!