why do i have one bald tire...?

I agree, more than likely it's your alignment. Have them check that out and balance your tires. Do you know if the car has been in any accidents, did you buy it salvage or anything of that sort? If so, it might be a problem with the frame; frame work is somewhat costly. I just got rid of a car like that, since the frame was welded together after an accident, and the welding came apart. It was gonna cost me a lot of $$ to fix, so I got rid of it instead. But in your case, it sounds more like alignment. Good luck

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i agree with the others. it sounds like alignment, probably the tracking part. that tire is probably sliding down the road instead or rolling.

take it to a alignment specialty shop and have them fix that wheel. something is really ****** up there and its dangerous to drive.