It doesn't say in the maintenance manual.

to rotate after the first 5K, then rotate back to front as neccesary (if tires start wearing unevenly). 2005.5 A4 Quattro.
On my last set, I rotated again at 22K and they wore pretty even until I replaced at 42K.

If you want your tires to have a normal life span, you must keep them properly inflated and rotate them regularly.

Next time you're in a large parking lot take a glance at other peoples' tires. Chances are you'll see 50% of them with abnormal tire wear that's obvious from a distance.

These are the folks that don't take care of their tires.

Many of them then bitch that the "50,000 mile" tires they bought sucked because they wore out at 25K.