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What do the numbers on a tire mean?


New Tire:

The DOT number appears on the sidewall of all tires intended for sales in the U.S., and designates the location of manufacture, the week and year of production, and the specific tire. DOT codes prior to year 2000 were a 10 digit code: (Example - AD70449248) digits 1 & 2 indicated plant of manufacture code. Digits 3 & 4 were the tire size code. Digits 5, 6 & 7 were optional tire type codes. Digits 8, 9 & 10 were the production serial week code. (The example would have been produced in Mayfield (DOT plant code AD), the size code would be "70," the optional design code would be "449," and the serial week would be "118.") In the year 2000, the serial number went to an 11-digit number allowing for a four digit serial week code to identify new decade.

 Numbers on a Tire


Retread Tires

Under the new Regulation, the first two symbols must identify the week of the year by using 01 for the first full calendar week in each year, 02 for the second full calendar week and so on. The final week of each year may include not more than 6 days of the following year. The last two symbols must identify the year. For example, 0101 means the first full calendar week of 2001, or the week of January 7 through 13, 2001.  

According to the new specifications, the minimum size of the date code may be reduced from 6mm (1/4") to 4mm (5/32"). This allows the figures to fit the same space as the old 3-digit code. Although 4mm is the minimum size, there is no limit to how large the figures can be. 

This new Tire Identification Regulation brings the U.S. into harmony with the United Nations Economic Commission for Europe (ECE) and the International Organization for Standardization (ISO) Recommended Practice.  

Truck tire retread markings as required by the Department of Transportation

Indicates Retread Manufacturers 3-Digit Identification Mark Tire size 2-Digit (Mold / Chamber) Identification Mark Tire Type Code (optional) Date of Manufacture (Week/Year) Identification Mark Required for retread California only *

* RS indicates retread was produced under Industry Retread Standards. The F1 or F2 symbol is required on retreaded tires for steer axle use in the state of California; F2 indicates the tire is acceptable for steer axle use and has been retreaded twice. California does not require the RS marking on passenger or truck retreads that have the original new tire DOT code intact.



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