Rotating tires on a dually

I used all tires when I rotated our 2001 dually. One tire at a time because of using the spare. I never did the job again because the tires didn't show a problem. Now with the Michelin tires we bought in 2011 I have had the dealer rotate and will again soon. I don't like old tires and one reason for not wanting to rotate . Free is why for this set of tires.
chevman