This past week, the owner of my former car came to me with this problem:
The tire is new and was mounted after she purchased the car from me. It has worn some inside of the bead. The tire was unmounted because of valve stem damage that is probably related to snow. Damage is on the driver's side rear (unpowered axle). Wear is only on the valve side of the tire.
What could cause this kind of tire wear? I'm having a hard time telling from the photo, but I think the rubber is worn down on a circular groove that may be from driving with a flat. Have you ever seen a tire with flakes of rubber inside the treads before? Is that wear sufficient enough to cause concern? Can low-to-moderate hand-brake turns in the snow be related (90-180 degrees, one storm, max 10 times?)
Mechanic she brought it to is saying the wear was caused by the valve stem. I'm having a hard time figuring how the valve steam could have created a wear pattern over a range of the tire, and that low down.