Originally Posted by
Dennie Spears
From Tire Safety Group, "For most tires, this expiration date should be six years from the date of manufacture. Tires age dangerously because of a chemical process commonly referred to as oxidation, which simply means that as the tire components are exposed to oxygen, the oxygen particles cause the flexible components of a tire to harden and become brittle. Over time, the tire will simply fall apart under normal stress, just like an old rubber band. Because this process occurs naturally, it does not matter if a tire is being used, stored as a spare, or simply waiting on a store shelf for an unsuspecting consumer."
If the tire is considered too dangerous for highway use after 6 years then it will be too dangerous for track use after 3 years. When I was selling industrial products, Gates Belts had a shelf life of 3 years. There is too much riding on this to take a chance on tires that are probably 3 years old on a 2 year old bike. There is a manufacturing date next to the DOT imprint on the side of the tire. It tells you the week and the year of manufacturing. Example: 2312 is the 23rd week of 2012. A lot of factors go into the life of a tire such as oxidation and ozone deterioration. If the bike is parked near an electric motor (air conditioner, compressor, fan, etc) then 2 years would be too much to risk.