There is a photo of my approach to the Audi (Ronal R8) Turbo wheel on Ben's
second wheel page:

<< http://hometown.aol.com/bentbtstr8/vanagoncafewheelspage2.html >>

I bored out the centers to the same diameter on all 4, 2.625 inches I believe
(all details are in the archives including my costs), used a 5/16" or 8 mm
spacer all around. For the fronts, I drilled the hub and countersunk the hole
through the spacer for metal screws to hold the spacer in place. This
seriously reduced the hassle of mounting the fronts. I then designed a set of
adapters to cover the center bore and hold the Audi black plastic hexagonal
(or octagonal) snap in caps. I cut them on a lathe out of a hunk of Al stock.
Used set screws to hold them in place. Look great and I haven't lost one of
the Audi caps yet. If anyone wants a copy of the CAD drawing for the
adapters, send an email request. Good looking (my taste) and no problem
running 215/75x15's. Haven't checked the weight difference to see if the
unsprung weight difference is significant.

Frank Grunthaner