Let's get one thing out in the open right away: The DOT Tire Identification Number isn't sexy, exciting, or cool. But it can be pretty useful, once you understand what it is.
Under Federal law, tire manufacturers are required to brand standardized information onto the sidewalls of all tires sold in the United States. This includes details about the tire's basic characteristics, construction, various capacities (load, speed, inflation pressure, etc.), as well as the DOT (Department of Transportation) Tire Identification Number. The DOT number is used for safety standard certification and also in the event of a tire recall by the manufacturer.
According to current regulations, the DOT Tire Identification Number must begin with the letters “DOT” followed by a series of characters (usually 10, 11, or 12 numbers, letters, or symbols). These characters identify the tire size and manufacturers specifications, as well as the manufacturing location and date the tire was manufactured (listed as week and year). People often think the DOT number is a product serial number, but it's actually a way to identify the manufacturers production batches.
If you look at the tire's sidewall and see a DOT number that appears to be incomplete, that's because the DOT's current regulations require the entire number to be branded on only one sidewall, while the opposite sidewall is branded with just the first few digits. To see the entire DOT number, just look on the other sidewall.
If your tire doesn't have a DOT number branded on its side, the tire doesn't meet all U.S. requirements. Not all tires are intended to be imported and sold in the United States, so the tire may have been developed and produced without being tested and confirmed to meet the U.S. Federal Vehicle Safety Standards (FMVSS). As a result, these tires cannot legally be used in the United States.
When you purchase new tires, your installer should provide you with a DOT card, so that you can record the DOT numbers of your tires and send them to the manufacturer. This information is important, as it'll be used to notify you in the event of a tire safety recall. If your installer doesn't provide you with a DOT card, you may also be able to register online on the manufacturer's website. Most manufacturers provide online registration for DOT numbers -- see the links below:
No online registration
No online registration