U.S. Department of Transportation rules require that tire manufacturers such as Yokohama provide specific information on their tires. Required sidewall data includes when and where a tire was manufactured. The date of manufacture for a Yokohama tire is provided in an easy-to-decipher code.
Find the Department of Transportation number on the tire. The number starts with DOT followed by about 12 letters and numbers. The full DOT number is only printed on the front side of the tire. A short, non-useful, DOT number is printed on the back of every tire.
Note and write down the last four digits of the DOT number. They will be all numerals such as 3207 or 1509. These numbers provide the tyre's date of manufacture.
Decode the manufacture date of the tire. The first two digits of the manufacture date indicate the week of production and the second two the year. For example, if the digits are 3207, the tire was produced in the 32nd week of 2007.
Calculate the age by subtracting the production date from the current date. Use 4.3 weeks to the month to estimate the month of manufacture. The tire with a 3207 production date was manufactured in August 2007. If the current date is October 2010, the tire would be 3 years, 2 months old.
Tires produced before 2000 may have a three-digit production date with a single number to indicate the year (for example, 309 for the 30th month of 1999).
Tires more than six years old may have unseen damage from decay and dry rot. It is dangerous to use tires older than six years.