I could not believe the difference in the ride and handling after getting my new Commander II's installed. There's a manufacture date printed on the tire it has the week and year number in a box on the side of the tire
With the short riding season up north here, it's easy to find low mile bikes - with old tires. Picked up this bike up with 2800 miles on it, and 7 year old tires.
The "seemed" OK, and since I had never rode the bike before, I had no way of knowing how the tires felt on it.
Sure did feel great getting the new ones on. Bike wise, and mental comfort.
And don't forget the climate that the bike was stored in has some impact too. Heat, humidity, ozone, etc.
"The anti-aging chemicals used in the rubber compounds are more effective when the tire is exercised...The repeated stretching of the rubber compound actually helps deter cracks from forming."
Tire Tech - Rubber Cracking