This post will probably end up being a Jon "I told you so" and a Peter "Ya wasted yer Lewbucks".
The Michelins on our bus were all dated 00 and 01 but were in very good condition with no checking or sidewall stress and they all had good tread when we started our cross country trip. I was however, watching them pretty closely for any rapid deterioration. All went well until a day or so after leaving Houston (JDUB, does the Royale have a nice new looking tire on it?) when I discovered some bad scalloping on the right steer tire. We pulled into the nearest truck tire store we could find and had the steer and tag swapped for a temporary quick fix.
Since we had planned on a brief visit with Roadrunner, I gave him a call and asked if he could knew of a good tire store. Dale was quick to recommend Dave Howell Tires in Pensacola where we pulled in for an alignment check and a new set of steers. The techs there showed me how all of the tires were close to the end and blamed it on lack of regular rotation, a situation which I was already aware of. The long and short is they gave me a terrific price on 8 new Michelin XZE's which they installed and computer balanced before doing a 3 axle alignment, which confirmed misalignment didn't cause the scalloped tire.
All was well UNTIL I noticed these tires had been manufactured in early 06. BUYER BEWARE, check new tire DOT dates closely. To their credit , the Howell folks were suitable embarrassed and while it delayed us a day in which we enjoyed Dale and Paulette's hospitality, they swapped the 06's for late '07's which were the newest tires they could find in the southern hemisphere.
Additional note: 12Rx22.5's are now a little used tire according to the info I received. Truckers now seem to prefer 11R and other low profile tires for better fuel mileage. Hence the difficulty in finding current manufacture tires.