Originally Posted by Chris55
If you rotate, it must be front to back.
Correct! This is due to BMW using directional tires.
Regarding rotating in general: with my E90, I changed between summer and winter rubber with the seasons. At each seasonal change, I would look at which tires had the most tread and put them on the rear.
BMW claims in the manual for the X3 that rotating can lead to unexpected handling, etc. I don't feel like I saw anything like that in my E90. I don't know if I will rotate with the X3 since it is AWD and such. I guess we'll see how they wear!