Then I began to feel some odd, subtle vibrations. I looked in the rear view mirror and saw bits of rubber flying off behind the car. That was my second clue that something was wrong. Traffic was light enough that I had no trouble merging over to the right as I gradually slowed. I made it to the offramp and eventually on to the side streets. My total drive distance since the vibration first presented itself was about a half mile.
While there was a subtle vibration, there was practically no difference in handling. The car behaved reasonably smoothly at all times. It accelerated as I expected, and the brakes felt pretty much like they normally do. I had no steering problems. While something definitely did not feel right, the car performed safely the whole time. I didn't think the damage would be too serious. When I finally found a safe place to stop, I was astonished to see this.
I've had tires fail before, but never had such a complete blowout/disintegration. That fact that the car performed so well despite this serious damage is a testament to the design and engineering that goes into a Subaru.
I popped on the full-sized spare tire and we changed plans. Next stop was the Costco tire store for new tires.
I'm not sure why the tire failed. They are the factory-original tires. I think they were rated for 50K miles. I've only got 42,000 miles on the car, but it is 7 years old. I was planning to replace the tires before the fall, anyway. This incident provided the encouragement to speed up that process.
Costco put a fresh set of 60K Michelin tires on the car. With as much as I drive, I'll probably have these for another decade or so.
I'm pleased with the new tires. The car seems to ride a little higher, but more importantly, the car rides significantly more quietly. The cabin noise has always been one of the biggest negatives to my 2004 Subaru Forester, but the new tires seem to make a big difference.
So while I definitely did not want to spend hundreds of dollars that day, it was money that needed to spent. And I only needed to pay the state disposal fee for three tires, instead of four, since the car itself gradually disposed of one tire across a half mile of Interstate 5.
And I can look forward to thousands of miles of safe driving in the years ahead.