DOT Tire Identification Number (TIN)(Lea en español)
Federal law requires tire manufacturers to provide standardized information permanently branded on the sidewalls of all tires sold in the United States. This includes information about the tire's basic characteristics, capacities and construction, as well as its U.S. Department of Transportation (DOT) Tire Identification Number used for safety standard certification and in case of a recall.
Current regulations require that Tire Identification Numbers begin with the letters "DOT," followed by eight to thirteen characters (see 12-character example in photo below) that can be used to identify the manufacturing location, tire size and manufacturer's specifications, along with the week and year the tire was manufactured. So while DOT Tire Identification Numbers are commonly but erroneously referred to as the tire's serial number, unlike the serial numbers used on most other consumer goods that identify one specific item, Tire Identification Numbers actually identify production batches.
Regulations also require the entire DOT Tire Identification Number to be branded on one sidewall while only the letters "DOT" and the first digits of the Tire Identification Number must be branded onto the opposite sidewall (shown below). Therefore it is possible to see a Tire Identification Number that appears incomplete, yet simply requires looking at the tire's other sidewall to find the complete Tire Identification Number.
Because not all tires are intended to be imported and sold in the United States, many tires are developed and produced without being tested by their manufacturer to confirm they meet all U.S. Federal Motor Vehicle Safety Standards (FMVSS). Without conducting the tests and certifying these tires meet U.S. requirements, these tires are not allowed to be branded "DOT" (shown below) and cannot be legally driven in the United States.
Mounting Orientation of Tire Identification Numbers (TIN)
It is recommended that tires featuring symmetric tread designs have their full DOT Tire Identification Number mounted outboard allowing them to be easily visible when the tires are installed on the vehicle.
Tires featuring asymmetric tread designs or asymmetric sidewall styling (white letters, etc.) should be mounted as dictated by the tread/styling. Tires featuring directional tread designs will typically result with full TINs showing on one side of the vehicle and partial TINs on the other.