Hub centering rings

[sciroccos at earthlink.net (Jim Ruffi)]

Hi.
I called the potterman today to order some goodies for my 88.  We agreed
that I would make sure I don't need spacers for my new wheels, as he's
selling me some lug bolts and we wanted to determine the length I'll need.
So, I checked the fit on the wheels (ATS Cups, 15 x 7) and they cleared the
calipers/rotors nicely - no spacers needed (as expected).

Unfortunately, I also discovered that the wheel center bore is greater than
my hubs...I need centering rings.  Does anyone know for sure what size
they're supposed to be?  I heard that Tire Rack sells 'em, but couldn't find
anything on their site.

TIA.

Jim