Not much help for the original poster, but maybe informative for others that are experiencing a similar problem.
Had the same problem with the Michelin LTX A/T tires on my 2010 Ford F-150, OEM installed. Cracks over 3/16" wide and 3/16" deep all across the tread area on all four tires. This was with 30,000 Km on the tires.
Took the truck to Costco a Michelin dealer, but they were unable to do anything for me as the tires were not purchased there.
Next went to the Ford dealer the truck was purchased from, they wanted to sell me replacement tires but would not warranty as that was tire manufacturer responsibility, told me Without looking at the tires, told me the cracking was caused by (take your pick, they were all referred to during the conversation) Heat, Cold, High Usage, Low Usage and also said the problems were just COSMETIC.
Next contacted three different Michelin dealers and they all wrote the off as NON WARRANTY, APPEARANCE DEFECT ONLY. Again telling me that Michelin refer to the problem as cosmetic, even though he admitted the cracks were quite deep. He also told me that cracking was a known problem in the industry with Michelin and BG Goodrich tires, both Commercial tires and Passenger tires.
My solution, buy new tires myself, just look for a non Michelin/BF Goodrich brand for this purchase and all tire purchases in the future. This is a household that has two collector cars with BF Goodrich tires, my wife's car with Michelin tires.
The replacement tires also included a replacement vehicle due to other problems with the Ford F-150. New tires are Toyo brand.
