im going to get me some new wheels and i was looking at the summit fast fives ill probably put some 15x4 in the front and 15x8 in the back, but wat i wanted to know is what bolt pattern do i get (4 lug) and also what is backspacing

 

4x4.25 is the bolt pattern. I have 15x4 and 15x8 Summit brand quick 8's. I run 5.50" backspacing with no quad shock with 265/50R15's right now. I will be going to 275/50R15 drag radials later.