How is Michelin at fault in any way? Their warranty covered nearly the exact % it should have. Sidewalls cracked in approx 3 years??? Tells you aging was not the cause but rather underinflated operaton caused extreme flexing and rubber fatigue and/or a lot of hard cornering or both. Even some of the tire shine coating products on the market causes tire rubber compound to prematurely harden which creates premature cracking. Research it!
Of course, the OP will deny "anything" was ever done to or happened with the tires and they just simply cracked for no reason at all. He was even the driver as it was his daughyer's car. He lives in the same geographical area of the country as I do and I've never had any of the more than 2 dozen Michelins on our vehicles developed any cracks in even 7+ years of daily use including our HD pickup trucks. The front tires on our 2004.5 Chevy D/A were put on in 2006 and are still on with over 90K on them with an average of 4-5/32 tread left as of last week and not a single crack is on the sidewalls. They will be replaced this summer due to tread wear. The same tire rears were replaced last late fall before our Florida trip as they were down nearly to the wear bars and had no sidewall cracks either.
I also do not see what the OP is trying to tell us!!!
Could it be Freddy Kruger slashing tires on L_gan?