Sounds to me like the tire is contacting the inner fender when you hit a bump. It's easy to verify, get a flashlight and look at the inner fender above the tire. If it looks sanded in a spot, that's it. The spot probably isn't as wide as the tire.
Check the tire sidewall inside and out to see if you can see evidence of rubbing. Sometimes the tire sidewall will hit a projection on the fender lip and it sounds horrible because it vibrates the fender. Those are easy fixes and nothing to be worried about. No vehicle is perfectly symmetrical so it can happen on any vehicle especially as they get older and the springs sag.
