How long should tires last before they dry rot?

06Fargo wrote:
Nevadastars - you did the right thing bringing the condition of these tires to the attention of the manufacturer.

Thank you, it is much appreciated. I certainly never meant to get a bunch of folks in a tizzy over it as in the other thread. I know the numbers on the tires were really important to the tire guy and the Michelin warranty department. They covered them under warranty fairly quickly, so I assume this is a batch that have had problems.