hey guys hardroc here i am putting a 4th gen rear in my 90 iroc and 4.11 gears but i need some help with backspacing .. i know i have 2 inches more on eother side stickin out but i am wonder if anyof you guys can help me figure out what backspacing to use to keep my wheels in and go just a lil bit wider rim ... 15x10 or 12... 15x10 available backspacin comes in 5 1/2 and 6 1/2 , 15x12 come in 5 1/2 6 1/2 7 1/2.. plus what kinda size slick or drag radial would fit nice my car sits factory height ...

 

Between the 10 and the 12 go with the 10 with a 6 1/2" bs. This will give you the max amount of rim inside the wheel well.

Unfortunately the rim/tire will still stick out a bit.

The factory tire height is 26". Choose a tire that suits your preference.

Good luck.