Weld wheels fit problem

I just picked up a set of used Weld wheels, 15 x 3.5 front, 15 x 8 rear. When I tried to install the skinnies up front, they slide all the way on and press up against the brake caliper, do i need a spacer? Do I need longer wheel studs? Not sure of any backspace numbers or if there is any. Thanks for any help.:shrug:
 
You shouldn't need a spacer at all, but you can't use the same lug nuts from your stock wheels (if that's what you had on there). The ones you need are rather long, because the studs don't stick out beyond the holes for the lug nuts.

Hope that helps....