Something in my tire

Hi, all. We had four new tires (Hankook Optimo H727) put on my car six months ago. Maybe three months ago I once heard this noise - like a bolt being dropped on concrete - when pulling out park. Thought nothing of it. Then, last month I had a shake at highway speeds, and got the front two tires rebalanced, which fixed that. Just this week, the metal bolt sound has been back with a vengeance; poking around, I discovered something rattling around inside the front-left tire, the source of the noise.
Whatever it is, I’m paranoid it may have caused some internal damage, and have had the donut on for the last two days. I have just a hunch it’s a wheel weight. But when I take it back to Firestone to get the tire demounted and the thing removed, if there’s damage should I expect them to take responsibility since it wasn’t noticed (or forbid, got worse) when they did the balance?

They should take responsibility, assuming they put something in the tire. They probably won’t, but they should. Get it in quickly - if your car is FWD, driving with a donut on the drive wheel can damage things.

Does your car have TPMS? It’s possible the sensor broke off.

Ditto to Shadow’s post. The first thing I thought of was the sensor…if your setup has one that’s not part of the valve assembly.

I wouldn’t start blaming people until you see what is inside the tire…

I think it is likely that you will find a piece of the TPMS has broken off, and is the offending part inside the tire of this mystery vehicle. For all we know, this vehicle might not even have a TPMS, but since you didn’t identify the make, model, or model year of the vehicle, we can only speculate.

Sorry, all. 1999 Subaru Legacy. No TPMS; I’m just used to forums showing make/model by my name, since it asked when I registered. Given Subaru AWD, I moved a full tire to the front, put the donut on the back, and am staying around town with the FWD fuse in to avoid drivetrain damage. Appointment with them tomorrow morning, will see what I find.
My main concern is how concerned I should be about damage to the tire, not really caring whose fault it is if there’s no harm done. Thoughts there?

Any metallic object tumbling around inside a tire (like a wheel weight) can damage the “liner”, the thin sheet of rubber that takes the place of the tube and keeps the air in the tire…A careful inspection with a bright light will reveal any damage to the liner…

Week-later update: A .5oz wheel weight slipped inside somehow. Not sure whether it was from the original mounting or the rebalance, but I got a good look inside and saw no abrasion at all.