but i will be using Nitto Nt555r in the rear and the 555 up front

 

305x45x18 will be fine in the rear. If they made 555s in that size I would have gotten them.

 

I just got done putting 255/45/18's in the front and 285/40/18's in the back. I think how it fills the wheel well hasa lot to do with the wheel itself (I'm no tire expert as you can tell). Mine fill the wheel well pretty good.

 

plstang that looks like that set up fits great...i hope i dont have any issues with my rear.