I don't believe OP stated that he has E70 fitment aftermarket rims. Aftermarket hub size can be anything. And I don't believe 0.04 mm difference (72.56 to 72.6) makes any difference, especially larger diameter wheels on X5 (too small of a difference). I have seen plastic rings that don't fit aftermarket rims correctly due to the clips or the ones with the large beveled edge that prevent the wheels from fitting flush.
Flybye, What manufacture wheels do you have and do you know the actual hub size? Also, as Ricky Bobby stated, it could be worn suspension component. But I can't believe that the dealer found a hub ring set for you and now stating they are not responsible for the shake.!?!
Do they have a technician who can better identify the source of the shake? Is the rim bent, out of round tire, bad bushing, etc...