Wheel offset question

[area53 at validpath.com (Jeff Toomasson)]

Is there anything that could be done to get a 15x7" but _ET12-13_ to fit on a 
VW?  I can't seem to get my head around offsets and the manipulation thereof.

I've been trying for years to find a particular style of wheel, but they just 
weren't that popular even when they WERE available (and, no, it's not the Ronal 
Teddy Bear!  ;)

The thing is, this particular style of wheel was actually very common on 
another marque (BMW) and relatively available in Germany (if I can convince 
someone to ship em to me).

I really don't want to settle for MoMo Quasars on my baby...  :)

thx, JT