Several listers have posted questions about minor vibrations they've had a hard time tracking down (Carlos, are you listening?). I was reading through a tech article on the S4 and came across this tidbit. I'm sure you experts out there are aware of it, but it sure got my attention:
From: Porsche Service Information 1988 928 S4 p.6-04
Prior to balancing a tire/wheel assembly,
a balance weight of 5 grams should be
installed above the tire valve stem on the
After balancing is completed, this weight must be removed.
This procedure compensates for the additional weight of the lockable wheel nut (approx. 15 grams).
Obviously, this applies only if you have a lockable wheel nut in place on the wheel.
Hope this helps someone.
1988 928 S4 A/T RMB