DOT Identification Numbers
The U.S. Department of Transportation requires tire manufacturers to brand standardized marking on the sidewalls of all tires sold in the U.S. to signify they have met all minimum safety standards.
The sidewall markings begin with DOT, and are followed by 10, 11 or 12 characters that identify the location, tire size, manufacturer specifications, and the week and year the tire was produced. The first two characters designate the manufacturer and the production plant code. The third and fourth characters denote the tire size. Characters five, six, seven and eight identify the brand and significant manufacturer information. The final three or four numbers list the week and year the tire was produced.
Regulations mandate that the full DOT identification number must be branded on the sidewall. On the opposite sidewall, only the letters DOT and the first three digits of the identification number are necessary.
DOT information is used to identify tire batches for safety recalls and warranties.