From JD Powers:
Are My Tires Too Old?
As we already mentioned, tires will oxidize as they age. In this process, oxygen from the air reacts with chemicals in the rubber, which causes them to harden. Eventually, they become brittle, and cracks and other damage can occur.
Oxidation in motorcycles usually is slow. However, it can be accelerated by heat and sunlight. Concrete can also leech moisture from the tires, further accelerating drying and cracking. For this reason, it is best to park in a cool place to extend your tire life. It is also wise to move your motorcycle regularly. Leave it in place for too long, and flat spots can appear.
As you can imagine, there’s some variation in how long it takes tires to age.
That said, the rule of thumb is to replace your motorcycle tires after five years, even if they appear to be in good condition.
If you don’t know how old your tires are, it is relatively easy to find out. First, there will be the letters “DOT” followed by a series of numbers on the tire’s sidewall. Once you have located these numbers, look at the last four digits. The first two digits signify the week the tire was manufactured, and the last two digits represent the year.
For example, imagine a tire with the last four digits, “1620”. In this instance, the tire was manufactured in the 16th week of 2020, or essentially, around the end of April.
Unfortunately, there is a lot of misinformation about how often you should change your motorcycle tires. Here is a quick guide to help clear things up.
www.jdpower.com