Ron,
While we agree on most things your continued use of 11+ year-old tires gives me the willies... I know you know better. Your operating load and storage conditions in no way mitigate the fact that tires time out. I hope I am wrong but IMHO: yours are a disaster just waiting to happen.
Given the critical interface between your rig and the road which = "tires' I cannot imagine pushing the envelope much less to such an extreme. I wish you luck but obviously you have already had your share...
But enough thread drift, go buy a new set of Michelins! :S
As always... Opinions and YMMV.
:B