I have the 16" iroc wheels on my car. Currently in the front I have a 3 inch gap between the top of the tire and the fender lip. In the rear there is about a 5 inch gap between the top of the tire and the fender lip. Right now I run 245/50ZR16 on all 4 corners. If I put a pair or 245/50 in the front and a pair of 255/50 on the rear will it close up the gap between the top of the tire and the fender lip in the rear. What im trying to is fill in the wheel well in the rear a little more. So will going from a 245 to a 255 close it up a bit more??

 

Very marginally.
Springs would be a much better closer.

 

Why you have 3" & 5", is a better question.

Even brand new, they wouldn't sit that high. Has the car been driven, since installation? Sometimes shocks, will hold the car up higher, if they haven't been cycled. Either by being driven on, or at least "bouncing" the car manually, to cycle the shocks.

 

well i havent put them on yet. its still stock. im approximating the 3 and 5 inch. I just wanna bring the rear down a bit lower to match the front so it sits level. I figured with 255 in the rear and 245 in the front it would bring that margin closer together.

 

tire size is probably not the best way to do that, as if you're going to run two different sized tires, you usually want the back tire taller anyway. the thing that affects ride height the most is springs, and then shocks.