Michelin tires seem prone to this problem. I have had two sets of tires replaced on my unit so far and it is only 8 years old. The problem is two-fold: Lack of regular use and exposure to sun. I am happy that Michelin is a respectable company. They have replaced both sets under warranty, prorated for treadwear. They covered 85% of the cost the first time and 65% the second time. I know the sun is a factor because the second time they only replaced the front tires and the outer duals. The inners were in good condition. They put the inners on the front axle and the 4 new ones went on the duals. As long as they continue to cover them I will continue to stick with Michelin. I bought replacement tires for my Dodge Dakota from Michelin because of the good customer support. I have been happy with the set on the truck. Our new Toyota Sienna has Michelins too.
