I sometimes depends on the rotor. Some BMW's use "disposable" rotors, meaning they wear out quite fast. On others, you can use a set of rotors with 2 sets of pads (typically for most high-end german vehicles). But my 2005 facelift e46 had those pesky "disposable" rotors and had to always be replaced with pads (luckily, warranty/maint. covered these). I MAY be wrong, but some 3.0's and 4.4's may have "disposable" rotors.

But never have rotors change without changing pads.

__________________