At 15,000 miles the tires started to roar like I was driving a monster truck. I called the dealership (Simmons Ford in Vicksburg, MI) and explained my problem but was told that the warranty only covered the tires up to 12,000 miles. I took it to the Firestone dealership and they checked the alignment and said all four tires had cupped and needed to be replaced due to a bad four wheel alignment. They believed it left the factory needing an alignment. Most of the miles driven were on the highway and I don't think 15,000 highway miles would cause all four wheels to to go out of alignment so I believe it was indeed a factory flaw. It never pulled one way or another and the first indication of a problem was the noise. Another example of poor customer service and a worthless warranty.