Identify cause of tire wear inside of rim

Question

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?)

Update

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.

Answer 1

This looks like damage from being run flat or with very low pressure. If the handbrake turns were all done turning in the same direction and the tire had low air pressure the sidewall would roll and rub in the turn. The damage would be confined to one side. I would replace the tire. The sidewall has damage. Any significent damage to the sidewall is like a bomb waiting to go off. It will fail you just don't know when.

Answer 2

That wear is caused by driving on a flat tire. I often slip tires off the bead when offroading and have to drive a short distance on the flat to get to an area where I can change the wheel and tire. When I get the tire replaced, it always looks like that inside, even from driving just a short distance (less than a mile).