Great looking X5. I have 20's now on my 4.8 Sport and thought of going to 22's like you mentioned. Now with the 20's on the 4.8 if you noticed there is a staggered look because of the tire being able to be matched different width and approximately same circumference (front and rear).
I hear that apparently if you go to 22's you no longer can have staggered wheels, in other words both front and rear tires will be the same width.
Have you arrived at this conclusion yet?
Can someone else shine a light on this; possibly someone rolling on 22's?

Good Luck.