A couple days ago, i noticed when going under a bridge while in the far left lane, there was an echo off the wall from my car. It was a funny flappy sound, perhaps coming from the driver's side rear tire. I imagined a chunk of tire tread hanging loose, flapping in the breeze. Today i noticed that the car shimmied violently at low speed. So when i got home, i decided on an inspection. It looked bad. It was worn thin - well past legal. It had a bump on it that i could sort of detect, but couldn't really see without taking the tire off of the car.
Time was pressing. I knew that the spare was a spare because it was showing the steel belt. I wasn't going to put something like that back on the car in anything other than a dire emergency. That's right, i have a real tire for a spare - not a donut. The spare was in the trunk, and therefore handy, and the tire store was about to close. If i hurried, and rolled in the spare, they'd put a new tire on it. I could get it onto my car in my leisure.
So, home again, i pulled the suspect tire off the car. No flap of tread hanging loose. It was showing some chord, and there was a bulge. The bulge was big. Huge. What had happened was that a large section of the tread was no longer attached to the tire, and that section had expanded. It made me nervous to look at it. It could explode at any moment.
So i put the new tire on the car, and let some air out of the old tire. No use having it explode in my trunk. Or my face.
The tire store is open late twice a week. Perhaps next week i'll replace this new spare.
In the mean time, i'll put gas in the car tomorrow, and see if i can get another quarter of a million miles out of it.