Actually, I've found a couple. It seems like X5M and X6M buyers do take them off and replace with others. The standard 300M's that those come with are 20" wheels.

The primary ones that I want wrap up the purchase for today are X6M 300M wheels; already bored out for X5; and 2008 TPMS sensors i.e. ready to install (when Spring arrives)

EDIT: I backed out of the deal above. Seller's communication was poor and something didn't seem right. Going to be looking for new OEM summer wheels in a month or two.