After four and a half years, I'm thinking of changing the wheels on my 04 4.4. It currently has 18x8.5 wheels. If I go to 20x9 all around, do I need the larger 4.8 style fender flares? I'm considering 275/40VR20 tires for this setup. Are there any drawbacks to the 20x9s in the rear other than slight loss in performance and less agresssive look?