Im pretty much lost on the topic of backspacing and what will fit and what wont. Now personally Im in love with the gunmetal Shelby Razor Wheels, i would like to get the 18 X 9 wheels with 255 35 18 upfront and 275 35 18 outback, my concern is whether or not it fill fit right. They offer to different version one with 5.5 in backspacing and one with 6.0 in backspacing. Right now i have stock brakes, i would like to convert to 4 wheel disc sometime in the future, i dont know if this will play a role fitment or not? So basically will they fit and which one fill fit best??