What Is A DOT Serial Number? (Meaning, Missing Numbers + More)

When shopping for tires, you need to have some crucial information such as the year of manufacture and serial identification numbers to know the age of your tires.

Have you ever wondered what the numbers and letters on your tire sidewall mean? This is the DOT serial number. What’s its role, and is it necessary? Here’s what I discovered.

What Is A DOT Serial Number?

A DOT serial number is a series of 7 to 13 letters and numbers branded on the sidewalls of all the tires sold in the United States. Under Federal law, tire manufacturers are required to brand standardized information, including manufacturer’s location, tire size, manufacturer’s code, week and year the tire was manufactured, and tire identification number.

To learn more about the DOT symbol, what each symbol signifies and how to read this code on your tire, keep on reading!

What Is A Dot Code?

As stated above, this code carries most of the information that can be used to identify a tire source.

DOT is short for the Department of Transportation; therefore, it’s an essential part of tracking tires and indicates that the tire has passed all minimum DOT standards for sale in the United States.

Introduced in the United States in 1971, the DOT number is now used by tire manufacturers worldwide.

How Do You Read A Dot Date Code On A Tire?

How Do You Read A Dot Date Code On A Tire?

When you buy a tire, you’ll spot the numbers and letters on the tire sidewall. But how do you read them?

As the car owner, it’s essential to know the meaning of the DOT code in order to determine the age of the tires and to track them in case the manufacturer recalls them.

According to current DOT regulations, the serial number starts with the letters “DOT,” then followed by 7 to 13 letters and numbers.

When reading this code, the first set of numbers represent the manufacturer code, the plant where the tire was manufactured, tire tread, or type of tire in some listings, while the last four digits represent the week and year the tire was manufactured.

Read More:  Can Run Flat Tires Be Repaired? + Other Common FAQs

Keep in mind that for the tires manufactured after 2000, there are four digits to show the date of manufacture. For instance, if the code is 0618, this indicates that the tire got manufactured during the 6th year of the week in 2018.

On the other hand, if the tire is a pre-2000 make, the last digits will be three instead of four. The first two numbers identify the week while the last number is the year manufacture.

Additionally, if the tires are from the 90s, instead of numbers, the tire will have a decade symbol, which is a triangle on its side at the end of the DOT serial number.

For identification and record-keeping purposes, the length of the tire identification number (TIN) is at 7 symbols for retreaded tires and 13 symbols for new tires, making it easier to identify which number is missing on the code.

What’s The Importance Of A DOT Serial Number?

What’s The Importance Of A DOT Serial Number?

Now that we’ve determined the meaning of a DOT serial number, why it is crucial to have it on your tires. Here are some of the reasons.

Tracking Purposes

Manufacturers add this code for easier tracking, which ensures that your tires are safe. Tire companies know the codes on all their brands of tires; therefore, they can inspect a particular line of tires and keep records of their supplies by using these sets of letters and numbers.

Tire Recall

When there’s a tire recall by the manufacturer, the DOT code comes in handy because car owners can simply check the numbers and letters and tires indicated on their tires in case they are from a faulty bunch.

Read More:  Do Tires Come With Rims? (Not What You Think...)

Once you purchase new tires, your installer should give you a DOT card which you need to record the DOT numbers and send to your manufacturer.

This information is essential because the manufacturer will use it in case there’s a tire recall; hence it’s vital for your safety.

However, if you don’t get this DOT card when getting your new tires, you can also register online on the manufacturer’s website.

Mark Of Approval

All tires manufactured in the United States have this stamp of approval from the Department of Transportation. This is to show that the tires meet the required standards and are safe for road use.

Age Determinant

One of the most critical uses of a DOT number is to determine the date of manufacture. Once you check this code, you can know how old your tire is, which determines how long you should use it on your car.

What Happens When DOT Is Incomplete or Not There?

If you notice that your tire’s sidewall has an incomplete DOT number, just look at the other sidewall for the entire number.

According to current regulations, the DOT entire number should be branded only on one sidewall, while the opposite side has the letters “DOT” and the first digits of the Tire Identification Number.

However, if your tire doesn’t have a DOT number in the sidewall, it doesn’t meet all the U.S. requirements.

This happens because not all tires are meant to be used in the United States; therefore, a manufacturer might have produced them without testing and confirming whether they meet the U.S. Federal Vehicle Safety Standards (FMVSS).

In this case, these tires cannot legally be used in the United States; therefore, you need to confirm these details before paying for a set of tires.

Does Every Tire Have A DOT Serial Number?

Does Every Tire Have A DOT Serial Number?

All tires approved for use in the United States have a DOT number, but some may not have this code if they have not gone through this legal approval.

Read More:  What Is Tire Camber Wear? + Other Common FAQs

Tires produced in other countries will have different codes. For instance, European tires have a number known as the E-Code.

What Other Information Do Tires Have?

Apart from the DOT serial number, tires have additional information branded on the sidewall to provide other vital details.

These details include tire specifications such as size, speed rating, load capability, and sidewall height.

Remember that these listings and details may vary depending on the type of tire you have bought and the manufacturer.

Just like with the DOT code, these details are also easy to read and understand; therefore, you should pay attention to them before purchasing a set of tires.

To know more about tires, you might also be interested in reading up on which tires wear faster, what are quiet tires, and how long do performance tires last.


DOT serial numbers are crucial for the safety of your tires, especially in case there’s a recall due to faulty manufacturer processes.

If you want to know the age of your tire or simply track your manufacturer, you can check your tire’s sidewall for the DOT code, which includes a series of 7 to 13 letters and numbers, each representing a particular element.

According to federal law, all approved tires must have a DOT code; therefore, if your tires don’t have one, they are not legally allowed to be used in the United States.

When reading the DOT serial number, you can get the year and week of manufacture, plant where it was manufactured, and other additional information.

Therefore, when purchasing a new set of tires, it’s best to check whether they have all this information.

Leave a Comment