On the left we see what appears to be a good tire. It has plenty of tread left. Most people would consider it to be a "safe" tire. But looking at the sidewall we can find the DOT Date Code -- in this case the 39th week of 2001. This is when the tire was manufactured. It is now the 43rd week of 2009 -- a hair over eight years later.
The tire failed. It flung it's tread, making a horrid racket as it beat the wheel well before finally breaking off. Fortunately I was on the freeway in rush hour onld going about 20 mph, in the rightmost lane. Pulled to the side, checked the damage, limped off the freeway and called for a replacement tire.
follow up. two days later:
My two front tires are good. Early this year one of them did the same thing. But they only replaced the two front tires, leaving the old tires on the rear. The company mechanic came out and replaced the one tire. I sent off an e-mail to fleet maintenance stating that I would appreciate the last tire be replaced before it flings it's tread like the previous two. They did.
The tire failure would have been a lot more intersting if I had been going at full freeway speeds.
