Since the OP did not say how many miles he puts on his coach a blanket statement about the tires rotting first may not be appropriate. I have been replacing my tires for the last 20 years long before they rot and as soon as they reach 50-60,000 miles, which is about four years. I always get a good tire credit towards my new tires so I feel it is worth it for the way we travel. IN any case, Michelin and Goodyear both have recommended tire rotation charts that indicate how to rotate the tires. I would guess that you are looking at around $150 to have it done, maybe less if you combine it with an oil change, lubrication, or other work.