the wheels you got are from a '84-88 audi 5000 turbo.   i had these on my
ex-87 van. i machined the centers to 2.5" ID, didnt touch the lug holes.  i
used audi lugbolts on the fronts and 911 studs on the rears (2wd van)  used
the carat wheel lug caps on the rears, painted the front grease caps silver
to match the wheels, looked fine.
chris