I have been searching on here and reading about all of the tire/wheel combos some of you guys are running and I have a couple of questions that I am not finding answers to. I have a 2008 F150 Regular Cab 2WD and I want to level it and put some 20x9's with 285x50x20s's (performance tires). I see a lot of people referring to backspacing and offset. I know what offset is but my previous car qualified as a European sports car so I dealt mostly with front wheel drives. I am not familiar with backspacing. What is it? and what should I look for in offset?