Originally Posted by +fireamx

Living in what use to be known as the "Rubber Capital of the World" all my life, I worked at that "Halfway decent tire company," (B.F. Goodrich) for about 14 years. I installed the 1st. generation Goodrich Radial TA's on my AMX in 1971, and kept them on my car for the next 27 years and 35K miles. I replaced them with the metric TA's that are currently on it before I took the car to Florida for a car show in 1998.
Now I don't claim to have "perfect pitch" so I can't say the sound a squealing tire makes as it ages, changes the older it gets. But it does harden, and that in turn noticeably decreases traction, which is a very good reason to get new tires.
I absolutely do not endorse keeping tires on your car as long as I have in the past, but IMO, changing a perfectly decent looking low mileage tire every 5 years is being premature. I'm certainly no expert, so use your best judgement, and inspect them on a regular basis.