[DanEC]

There is another issue with aging tires in addition to, but of less concern than catastrophic failure - traction. I've had a good opportunity to see this on my Wife's front drive Toyota Highlander. We bought it new with Toyo tires and within a few months started to experience problems with loss of traction when starting from a stop on wet roads or an up-hill grade. Sometimes it would just sit and spin and barely creep forward. After a couple years of enduring that but still with lots of thread on them, we put a set of Continentals on it and voila - no more traction problems. Starts on wet streets and up-hill grades were no longer met with spinning tires. Great news -- for 2-1/2 years, after which the tires began showing more and more evidence of being sensitive to traction loss. By 3 years time they were literally as bad as the original Toyo's. My Wife ran over something on the Interstate and experienced a catastrophic blowout which prompted yet another change of tires with only about half of the thread gone on the Continentals. With a set of Michelins we are back to having traction again. But considering how well the Continental's were rated (even the owner of the tire store we frequent uses them on his car) I'm expecting about 3 years service out of them. The point is that the rubber compounds have limited life and get harder with age and slipperier - maybe in as little as 2-1/2 years - and just when you might need a little traction in a sticky situation, it might not be there.