Tire Date Code: Check 4 Digits Before Driving a Stored Supercar
Look for the letters DOT on the tire sidewall. The last four digits of the Tire Identification Number after them give the week and year the tire was made, in a WWYY format. A code ending in 2524 means the 25th week of 2024. For tires built in 2000 or later, that is the whole rule.
TL;DR:
- If DOT appears without its date code, inspect the opposite sidewall; the date may face inward, and a mirror or phone photo can help.
- Record every character after DOT, not just the date, because the full tire identification number can support recall checks and clarify unclear markings.
- The first two digits identify the week, counted from the year’s first full calendar week, while the last two identify the year.
- Calendar age alone cannot establish whether a tire is safe; assess cracking, stiffness, bulges, storage conditions, and the tire maker’s inspection or replacement guidance.
Table of Contents
- Where to find the DOT code on a tire sidewall
- How to decode the last four digits of the date code
- Special cases: older tires, retreads, and worn markings
- What the manufacture date means for tire safety
- Quick checklist: locate, decode, inspect, document, act
- Why tire age matters more on exotic and stored cars
- FAQ
- Sources
Where to find the DOT code on a tire sidewall
Start with a flashlight and a clean rag. Wipe road grime from the lower half of the sidewall, then look for the letters DOT molded into the rubber. The characters that follow, read left to right, are the Tire Identification Number, or TIN. The tire date code is the last four digits of that string.
The TIN is not one random jumble. After the DOT letters, it holds a plant code, then optional manufacturer codes, then the four-digit date. The Tire Industry Association explains that the final four numbers show the week and year of manufacture, while the earlier characters identify the plant and production details. You do not need to decode those earlier characters to find the age, but you will want to record them for recall checks.
If you see DOT and a plant code but no four-digit date, check the other sidewall for the date code.
- Check the inside sidewall. On a car, the date side may face the suspension. Turn the steering wheel to full lock to expose more of the inner edge.
- Use a mirror and a light. A small inspection mirror on a handle lets you read the inner sidewall without jacking the car.
- Photograph the code. A phone photo with the flash on, or at a low angle, makes shallow lettering easier to read.
- Wipe, then look again. Dirt and tire shine can hide molded characters.
- Record the entire TIN. Write down or photograph every character after DOT, not only the last four digits. You will need the full string if you ever check for a recall.
Pro Tip: Shine your flashlight across the sidewall at a shallow angle rather than straight on. The raised letters cast tiny shadows, and a faint date code that looks blank head-on becomes readable.
If you keep tires on a spare wheel, a trailer or a project car that sits for months, check each one. The date can differ between tires on the same vehicle, so never assume all four match.
How to decode the last four digits of the date code
The date code follows a simple pattern. The first two digits are the week of the year, and the last two digits are the year. Think of it as WWYY.
For tires made in 2000 or later, federal rules spell this out. The regulation at 49 CFR § 574.5 requires the date code to be four numerical symbols identifying the week and year of manufacture. The first two symbols give the week, using “01” for the first full calendar week of the year, and the third and fourth symbols are the last two digits of the year. Its own example reads 0109 as the first full week of 2009.
Here is how to work through any code:
- Isolate the last four digits of the TIN after the DOT letters.
- Read the first two digits as the week number. The code can use 53 for the week when applicable.
- Read the last two digits as the year. Add “20” in front for a tire built in 2000 or later.
- Convert the week to a rough month if that helps. Week 25 falls in mid to late June, and week 01 is early January.
Now try some real examples:
- 2524 means the 25th week of 2024.
- 0308 means the 3rd week of 2008.
- 2910 means the 29th week of 2010, the same example the Tire Industry Association uses.
- 0412 means the 4th week of 2012, matching the example in U.S. Army safety guidance on checking tires before trips.
Regulation at a glance: According to federal tire identification rules, the date code is four digits that identify the week and year, and “01” marks the first full calendar week of the year. That wording is why a code like 0109 is read as the first full week of 2009, not simply “January.”
A note on week numbering. The rule counts from the first full calendar week of the year. If you see 53 in the first two positions, read it as the week number.
If the last four digits look odd, check that you are reading the final four digits of the TIN, not a digit group from the plant code.
Special cases: older tires, retreads, and worn markings
Not every tire follows the clean WWYY pattern. Here are the situations you may run into.
Older tires. If you find a date code that does not follow the four-digit format, ask a tire professional to identify it and check the tire’s condition.
Retreaded tires. If you are buying or inheriting a vehicle with retreaded tires, ask the seller or a tire shop to check the tire’s markings and condition.
Missing, worn or covered codes. Sometimes the date simply is not there. The tire may be mounted with the date side against the vehicle, the lettering may be rubbed away by curb scrapes, or the tire may be a spare buried in a trunk well. When that happens:
- Clean the sidewall and try again with raking light and a mirror.
- Look at the opposite sidewall in case the code was only molded on one side.
- Photograph whatever characters you can read, including the plant code.
- Ask a tire professional or the tire manufacturer to verify the age from the partial TIN.
When to bring in a professional. If you cannot find the date, if the markings look inconsistent, or if you spot damage, have a tire shop dismount and inspect the tire. They can read the inner sidewall properly and check the full TIN against recall databases. A tire with an unreadable date and unknown history is best treated as an old tire until proven otherwise.
- Missing date code: assume unknown age and get it inspected.
- Three-digit code: likely made before 2000, so plan to replace.
- Retread marking: check the casing age as well as the tread.
- Worn or damaged sidewall lettering: photograph it and consult a professional.
What the manufacture date means for tire safety
Once you know the age, the next question is what to do about it. This is where many drivers go wrong in both directions: some replace perfectly good tires on a birthday, others keep ancient rubber because the tread looks deep.
Industry guidance is clear that age is one factor, not a switch. The U.S. Tire Manufacturers Association says, in its tire facts, that it is not possible to accurately predict the serviceable life of a specific tire from calendar age alone. Heat, sun exposure and how the vehicle is used all speed up rubber degradation in different ways for different cars. The same guidance stresses that tread depth, storage conditions and signs of rubber breakdown such as cracking or stiffness matter, and that age deserves extra attention on infrequently driven vehicles.
Some vehicle and tire makers publish their own guidance about when to inspect or replace tires. Check your owner’s manual and your tire maker’s literature for guidance on your specific tires. Treat that as manufacturer practice, not a federal rule. Your owner’s manual and your tire maker’s literature are the right place to find the number for your specific tires.
Combine the date with what you can see. Replace or get a professional opinion when you find:
- Cracks in the sidewall or between tread blocks, especially fine webbing that looks like dry skin.
- Hardness or brittleness. Rubber that feels stiff and has lost its slight tackiness is aging.
- Bulges or bubbles on the sidewall, which can signal internal damage.
- Tread separation, where the tread edge lifts or shows uneven wear patterns.
- Vibration you cannot balance away, which can point to internal changes.
Environment shapes all of this. Tires that live in a hot garage, sit in direct sun, or rest on one flat spot for months age differently from tires on a daily commuter. Keeping rubber clean and protected helps: a gentle water-based dressing and regular washing keep road salt and grime from sitting on the sidewall. If you are looking for care products, this UK guide to tyre dressings covers what to look for when protecting sidewalls from the elements. Dressings do not reverse age, though, and they never replace an inspection.
Pro Tip: Check the date and the condition together every time you wash the car or change the oil. A quick look at each sidewall can help you spot a problem before it becomes a roadside event.
Stored and low-mileage vehicles deserve the most attention. A car that is driven infrequently can wear its tread slowly while its rubber ages on the calendar. Deep tread on a tire that is many years old is a false comfort. If your vehicle sits for long stretches:
- Check every tire’s date code, including the spare.
- Inspect for cracking and flat spots after each storage period.
- Keep tires inflated to the recommended pressure, and store the vehicle out of direct sun where you can.
- Replace tires on condition and age together, not on tread depth alone.
Quick checklist: locate, decode, inspect, document, act
Use this list the next time you walk around your vehicle.
- Locate. Find the letters DOT on each tire, and photograph the full TIN. Check both sidewalls if the date is not on the first one you read.
- Decode. Read the last four digits as WWYY, with the first two as the week and the last two as the year. Write the result next to each tire’s position.
- Inspect. Look for sidewall cracking, bulges, stiffness and uneven tread wear. Run a hand carefully over the tread to feel for irregular spots.
- Document. Save your photos and notes. Record the full TIN so you can check manufacturer and NHTSA recall tools, and ask a tire professional if any marking is unclear.
- Act. If a tire is old for its use, shows damage, or has an unreadable code, have it inspected by a professional before your next long drive.
Why tire age matters more on exotic and stored cars
Here is my view: tread depth is the wrong number to trust on a car that barely moves. Supercars and other high-value cars often rack up few miles, so the rubber looks new while the compound quietly stiffens. A date code takes seconds to read and tells you what a tread gauge cannot. Pair it with a look at how the car has been stored. And when a replacement is due, correct identification of the right part for your specific model matters just as much as the date on the old one. For any safety decision, ask a qualified tire professional.
— Artem
FAQ
How long are tires good for based on the date code?
There is no single legal expiration date. The U.S. Tire Manufacturers Association says calendar age alone cannot predict a specific tire’s serviceable life, because heat, storage and use change how fast rubber degrades. Some manufacturers advise when to inspect or replace tires, so check your tire maker’s guidance.
How do I read the tire date code?
Find the letters DOT on the sidewall, then look at the last four digits of the string that follows. The first two digits are the week and the last two are the year, so 2524 means the 25th week of 2024, as the Tire Industry Association describes. If the date is missing, check the opposite sidewall.
Can I still use an old tire if the tread looks good?
Deep tread does not guarantee the tire is sound. Rubber ages from the inside and the outside, and cracking, stiffness or bulges can appear on a tire with plenty of tread left. Inspect the sidewalls and the date code together, and have a professional look at any tire that is old, damaged or has an unknown history.
What if my tire only shows a three-digit date code?
If the code does not follow the four-digit format, have a tire shop identify it and check its condition before you drive on it.
Sources
- Tire Facts | USTMA
- 49 CFR § 574.5 - Tire identification requirements. | Electronic Code of Federal Regulations (e-CFR) | US Law | LII / Legal Information Institute
- Reading a Tire Sidewall - Tire Industry Association
- Check your tires for wear, age as you prepare for trips | Article | The United States Army
