Here's a great wheel and tire program I stumbled upon, when I was looking around for wheels, and trying to find something close to the set up I had. I got lucky and found 2 different set of rims in a 17, with the same Back Space and Off-Set, I had with the 15s. This program helps visualize it.
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com