What do you call it?
Your tire appears to be starting to form a black hole like suction on the sidewall as if it was eating itself.
What is the cause of this tire phenomenon?
Tire Sidewall Indentation
Location: Occurs in area of splices in tire carcass plies
Explanation: sidewall indentation occurs where the layers of carcass plies are doubled due to the overlap of ply cords and that particular part of the tire stretches less than the rest of the tire when the tire is inflated. The wider the ply splices are made, the more cords there are in the overlap, making the sidewall indentations even deeper.
Action: The Rubber Manufacture Association has determined these indentations affect the cosmetic appearance and not the tires performance.