[BeemerX1]

Look at 405 M style for F30 3 series. F20 (1 series) has them as well but they're only 19" and ET would be completely wrong without spacers.

There isn't much goodies for the X1, no Performance parts at all I think.
I went true all 20" and 21" rims and looked at the ET value and came across like 4-8 style I loved and then decided. M6 GC rims where to wide and 7 series 21" rims only fit if you lower your profile of the tire and even then get a small tire on wider rim, like 225/30/21 on a 8,5J rim. For riding you need to drive like crazy gently and for Xdrive or higher weight of a X1 compared to smaller/lighter car I didn't dare it.

Attached some rims that will fit the X1.
(21x8,5J - 463 style is tricky like a mentioned)