The 18" are the ones we saw on the F83 mule here:
http://f80.bimmerpost.com/forums/sho...d.php?t=943852
The 19" look like they might be the ones that have popped up on various mules in the past (but in black), and that people were hoping would be a standard factory wheel option. The good news is that you can get them, but the bad news is that they are narrower than stock.
It will be interesting to see which tires and in what sizes these are offered with. I don't recall BMW recommending a staggered winter setup in the past.