How To Decode DOT Tire Numbers | Read The Sidewall

DOT tire codes show the plant, maker’s internal code, and the week and year the tire was built.

A DOT number is the tire’s built-in ID tag. Once you know where to look, you can tell when the tire was made, spot mismatched sets, and catch old stock before it goes on your car. That takes less than a minute, and it can save you from buying a “new” tire that has already spent years on a shelf.

The part most drivers need is the date code at the end. Still, the rest of the string has a job too. It points to the plant that built the tire and to maker records used for tracing batches and recalls. If you shop for tires, rotate a spare, or check a used car, reading this mark is one of the handiest sidewall skills you can pick up.

How To Decode DOT Tire Numbers On Any Sidewall

Start by finding the letters DOT on the tire sidewall. Follow that mark to the end of the full code. The last four numbers are the part most people want, because they tell you the build week and build year.

Start With The Last Four Digits

If the code ends in 3524, the tire was made in the 35th week of 2024. If it ends in 0126, it was made in the first full calendar week of 2026. That’s the plain-English read most buyers need when they’re standing in a shop or checking a car in a driveway.

A Simple Way To Read The Date

• First two digits: build week of the year
• Last two digits: last two digits of the build year
• 3524: week 35 of 2024
• 0308: week 3 of 2008

There’s one small twist that catches people. Under the federal rule, week 01 is the first full calendar week of the year, and that week runs from Sunday through Saturday. You don’t need to map that out every time, though. For most tire checks, the week-year read is plenty.

Then Read The Front Part Of The Code

Everything before the date is not random. Under 49 CFR § 574.5 tire identification requirements, the opening group is the plant code assigned by NHTSA. On newer U.S. tires, that plant code uses three symbols. After that comes the maker’s own six-symbol code on new tires. Brands use that block to track tire details in their records.

That means the front section is useful for tracing a tire, while the back section is what tells you age at a glance. If you only want to know whether a tire is fresh stock or older stock, skip straight to the last four digits. If you’re checking a recall notice or matching a set across the car, copy the full string.

Where The DOT Code Sits And Why It Can Be Tricky

The code is molded into the sidewall, usually in smaller text than the size line. Dirt, curb rash, and low light can make it easy to miss. A lot of people also stop when they see “DOT” on the outer sidewall and assume they’ve found the whole thing. Sometimes they haven’t.

On many tires, the full TIN with the four-digit date appears on only one sidewall. The opposite side may show a shortened DOT mark without the full ending. So if you can’t find the date on the side facing you, check the inner sidewall too. A flashlight and a quick phone photo make this much easier than squatting and guessing.

• Wipe the sidewall clean before reading the code.
• Turn the steering wheel to open up space on front tires.
• Roll the car a few inches if the code sits near the ground.
• Take a photo and zoom in instead of trying to read every character in one glance.

The DOT Tire Number Breakdown At A Glance

Part Of The Mark	What It Means	What You Do With It
DOT	The tire is marked under U.S. Department of Transportation rules.	Use it as your starting point when scanning the sidewall.
Plant code	The factory identifier assigned by NHTSA.	Useful for recalls, tracing, and batch checks.
Maker code	The brand’s internal identification block for the tire.	Helpful when a recall notice lists full TIN ranges.
Final four digits	The build date code.	This is the part most buyers need first.
First two date digits	Week of the year.	Use them with the last two digits to pin down the build window.
Last two date digits	Last two digits of the year.	Tells you whether the tire is fresh stock or older stock.
Full TIN on one side only	The dated version may be on the inner sidewall.	Check both sides before you assume the date is missing.
Shorter or older layouts	Retreads and older tires can look different.	Read the date ending first; if it is three digits, pass on it for normal road use.

What A Real DOT Number Looks Like In Practice

Say you spot a code like DOT 1AB 6CD8EF 3524. The spaces may differ from brand to brand, but the reading flow stays the same. Start at the end. 3524 means the tire was built in the 35th week of 2024. Then move left. 1AB is the plant code. 6CD8EF is the maker’s internal code.

That’s all you need for a clean first read. The federal rule tells you what each block is for, while NHTSA TireWise notes that the full TIN may not be on both sides and that the last four digits give the week and year the tire was made. If you’re checking a used car, do this on all four tires, not just one. Mixed dates can point to a past blowout, a single-tire replacement, or a set that was pieced together.

If you find a three-digit date ending instead of four digits, the tire is from before 2000. At that point, you don’t need a long debate about service life. It’s old enough to skip for normal road use.

What The Code Does Not Tell You

The DOT number is handy, but it does not tell you everything. It does not give tread depth, load index, speed rating, inflation pressure, or whether the tire still fits your car. Those marks live elsewhere on the sidewall or on the placard in the driver’s door area.

So after you decode the date, pair that read with a quick visual check. Look for dry cracking, bulges, odd wear, puncture repairs, and uneven tread across the set. A newer build date does not erase bad storage, road damage, or a poor match to the vehicle.

Tire Date Code Examples You Can Read In Seconds

Code Ending	Read It As	Plain-English Meaning
0126	Week 01, Year 26	Built in the first full calendar week of 2026.
0524	Week 05, Year 24	Built in the fifth week of 2024.
3524	Week 35, Year 24	Built late in the summer of 2024.
5320	Week 53, Year 20	Built in a year that carried a 53rd production week.
279	Week 27, Year ending in 9	Pre-2000 tire date style; too old for normal road service.

Common Mistakes That Lead To Wrong Reads

The biggest mistake is reading the wrong number. Tires carry size markings, load ratings, speed symbols, and other molded text, so it’s easy to grab the first four digits you see and call it done. The build date is only the final four digits of the full DOT identification number.

• Reading the size line as the date: 225/45R17 is tire size, not build age.
• Stopping at the outer sidewall: the full dated code may be on the inner side.
• Using one tire to judge the whole car: each tire can have a different build date.
• Confusing fresh tread with fresh age: low miles do not change the manufacturing date.
• Ignoring a spare: a little-used spare can still be old.

Another slip is treating the middle part of the code like a consumer-friendly model label. It usually isn’t. The plant code and maker code matter for tracing and recall work. The date ending is the part built for quick reading by a shopper or owner.

When The Date Code Should Make You Pause

A tire can look clean, deep-treaded, and still be old. Age alone is not the whole story, but it matters. On its tire pages, NHTSA says some vehicle and tire makers call for replacement at six to 10 years, even if tread remains. That’s why a date check is not trivia. It gives you context before you spend money or head out on a long trip.

If a shop brings out tires with dates that are older than you expected, ask when they were received, how they were stored, and whether a fresher set is available. If you’re buying a used car, note whether all four dates are close together. A matched set usually points to a cleaner maintenance story than a random mix spread over many years.

Also watch for signs that age and condition are lining up in a bad way: small sidewall cracks, a harsh ride, tread blocks that feel hard, or vibration that does not fit the tread wear you can see. The DOT date will not diagnose those problems by itself, but it gives you a firm starting point.

A Five-Minute Sidewall Check Before You Buy

Once you know how to read the mark, use the same short routine every time you shop or inspect a vehicle:

1. Find the full DOT code on each tire.
2. Read the last four digits first.
3. Write down or photograph all four dates.
4. Check whether the dates are close together.
5. Scan the sidewalls and tread for damage or uneven wear.
6. Match the tire size and load rating to the vehicle placard.

That little habit pays off. You stop guessing. You catch old inventory. You spot mixed sets before they surprise you. And you can walk into a tire shop or a used-car sale knowing exactly what the sidewall is telling you.