Bob, I was told the very shallow creases are just a "blemish" but when we had depressions the size of the one you describe it was a defect in the tire. Ours were Goodyear but they replaced them, prorated to tire wear. One was new enough there was no charge. We also had one tire develop a bubble on the outside. This might have been due to some kind of bruising against a curb but Goodyear said it was a defect, a separation. This picture was taken three days after we noticed the bubble and removed the tire. It was growing daily.
