Well, the good news is that I (well, Marc) found the bulge in my tire before anything dangerous happened. The bad news is that all the tires are worn (I didn't think to get the tires rotated when I got the car from Colleen, and she certainly never had them rotated when it was under her care).
So I'm probably paying for 4 new tires. *hopes but doesn't expect that tires are still under warranty.* This was not budgeted. I'm cranky.