Tech Tip: How Old Are Those Tires?
by Dennis Darnall,
Do you know how old those tires on your Z are ? If you purchased them then you know when they were put on the car. What about those used tires you picked up or the tires that were on the car when you purchased it. According to tire expert you shouldn't buy "new" tires if it was manufactured more than 2 years ago. Rubber degrades over time and if it was exposed to heat or sunlight it may not be the best deal for you.
You can determine the tire's date of manufacture by the Department of Transportation serial number that is on every tire. Here is an example of a DOT serial number: DOT M3TA C66X 228. The date code is the last 3 digits. The date code of 228 indicates that this tire was manufactured in the 2nd week of 1998. I was surprised at how old some of my tires are, I guess that's why the sidewalls are starting to crack.