Here's the X3 manuals for a couple of years, right on the Home Page
of this site/sister site: X3 World. Hit the manual link and give it a
read...
Here are some questions to fill in the lack of specific info in your
original post:
-What year is your X3?
-What do the maintenance dash lights tell you?
-Wheel rotation is not rec'd by BMW on Xs.
Good luck...it reads as if you'll need it.
http://www.x3world.com/