How to Read a Tire's Date Code (DOT Number)

Why the date code matters

Federal rules require a tire identification number on new tires. It is often called the DOT code, and part of it tells you when the tire was made.

That matters because tire makers give age guidance as well as tread guidance. You can only follow it if you know how old a tire is. This is true for tires on your vehicle, a spare, or a set about to be delivered.

Where to find it

Look on the sidewall for the letters DOT. The identification number follows them.

Federal rules require the number to be labeled on one sidewall of each tire. Retailers also point out that one side shows the full code, ending with the four-digit date code.

That means the date may be on the inner side of the tire. If you only see a short code on the outside, check the other side. On a tire already mounted, you may need to look from behind the wheel with a flashlight, or ask a shop to check.

How the code is built

For new tires, the tire identification number has 13 symbols. They fall into three groups.

• Plant code: 3 symbols that identify the manufacturer's plant
• Manufacturer's code: 6 symbols that describe tire characteristics or the brand owner
• Date code: 4 symbols that give the week and year

The date code is the last group. You do not need to decode the other groups to find the age.

Reading the four-digit date code

The first two digits are the week of the year. The last two digits are the year.

Under the federal rule, 01 is the first full calendar week of a year, 02 is the second, and so on. The rule gives the example 0109, which is week 1 of 2009.

Here are a few more.

• 2225 is the 22nd week of 2025
• 3520 is the 35th week of 2020
• 3118 is the 31st week of 2018

Weeks run from 01 up to 53. A 53 can appear because the first full calendar week is counted as week 1, so late December can fall in a 53rd week, as Continental explains.

Older tires with three digits

Discount Tire says that before 2000 the date code used three digits. The first two give the week and the last gives the year within the decade. The code does not say which decade, so a three-digit code means the tire is very old.

Retreaded tires

Retreaded tires have a shorter code. The federal rule gives them 7 symbols, which leaves out the manufacturer's code. Per Continental, each retreading gives the tire a new code from the retread facility.

New tires on a passenger vehicle will carry the 13-symbol version.

Step by step

1. Find DOT on the sidewall. If you cannot see it, check the other side.
2. Find the last four digits of the code that follows DOT.
3. Read the first two digits as the week, from 01 to 53.
4. Read the last two digits as the year.
5. If there are only three digits, the tire was made before 2000 and is very old.

Do this for every tire, including the spare. Tires on the same vehicle can have different dates.

Turn the code into an age

Count forward from the week and year in the code to today. A tire made in the 35th week of 2020 turns six years old in the 35th week of 2026.

Michelin recommends that tires be inspected at least once a year by a trained tire professional after five years of service. It recommends replacing tires ten years after their date of manufacture, regardless of remaining tread depth or apparent condition.

A retailer, Discount Tire, says it recommends considering replacement at six years and will not service tires that are ten years or older.

Your owner's manual may also have guidance. Our guide on when tires need replacing covers tread depth and damage, which matter as much as age.

What the date code can and cannot tell you

The date code gives the week and year a tire was made. That is all it records.

It does not show how a tire was stored, how far it has been driven or whether it has been damaged. Those need an inspection. This is why Michelin pairs its age guidance with a yearly inspection by a trained tire professional after five years of service.

Two tires of the same model can carry different dates. Check each tire rather than assuming a set matches, and write the codes down if you are comparing quotes.

Check new tires when they arrive

The date code is the week and year the tire was made, not when it was sold. A new tire can carry an earlier date.

When tires arrive or are installed, read the code on each one. If a tire looks much older than you expected, ask the seller about it before it goes on the vehicle. Ask what their policy is on tire age. Our guide to buying tires online and installation covers what to check on delivery.

The rest of the sidewall

The date code is one of several markings. The size, load index and speed rating also matter when you shop. See our guide to reading a tire sidewall.

When you are ready to look for tires, confirm the size on the sidewall or the driver's door placard, then use the tire finder. To compare a size you are considering with your current one, try the tire size calculator.

A size such as 225/65R17 is only part of what is printed on the tire. The DOT code is separate from the size and is just as useful to read.