So I'm not great when it comes to calculating wheel stuff, but I've gotten gotten better. From what I understand, the factory 16" wheels are 5.45" backspacing. If I move to 4.5" backspacing does that mean my tires are going to stick out an extra inch, or are we looking at a half inch (ish) on each side?

Thanks.

 

Reducing the backspace for 1" will cause your wheels sticking out one more inch!
(Example by adding 1" spacer!)
Carefull when you use a new wheel! Many wheels are 9", and with 4.5" backspace this will end up 2.5" sticking out!