Sizewise....it's whatever fit's the application.
But nothing in their lineup really works well on the X.......
Spokes are just too thin and I had a brief period of wheel fanatic insanity when I posted this message.

Now on a coupe, maybe a white 335i diesel if I see myself, then a set of RSGT is in order.

Yeah, to pull the BBS wheels off, you'll need them in 22" and your X5 slammed.

Not hot.