When it comes to determining the age of a tire, it is easy to identify when a tire was manufactured by reading its Tire Identification Number (often referred to as the tire’s serial number). Unlike vehicle identification numbers (VINs) and the serial numbers used on many other consumer goods (which identify one specific item), Tire Identification Numbers are really batch codes that identify the week and year the tire was produced.
The U.S. Department of Transportation (DOT) National Highway Traffic Safety Administration (NHTSA) requires that Tire Identification Numbers be a combination of the letters DOT, followed by ten, eleven or twelve letters and/or numbers that identify the manufacturing location, tire size and manufacturer's code, along with the week and year the tire was manufactured.
Tires Manufactured Since 2000
Since 2000, the week and year the tire was produced has been provided by the last four digits of the Tire Identification Number with the 2 digits being used to identify the week immediately preceding the 2 digits used to identify the year.
Example of a tire manufactured since 2000 with the current Tire Identification Number format:
DOT U2LL LMLR 5107
DOT U2LL LMLR 5107 Manufactured during the 51st week of the year
DOT U2LL LMLR 5107 Manufactured during 2007
...read the full guide with pics here
Determining the Age of a Tire 
Linear Mode
