You need to go to Billet Specialties web site and download there wheel backspacing worksheet. Once you've downloaded that follow the instruction and you will be able to figure out your backspacing.
The other thing to consider is are you going to upgrade your front or rear brakes. If so do that first as the thickness of the rotor hat may/will change and that will affect how your wheels fit.
http://www.billetspecialties.com/ite...pid=596&rdir=1
