US tire rules put three duties on a passenger tire. It has to be certified against a federal safety standard, it has to carry an identification number molded into the sidewall, and whoever sells it has to record who bought it. The DOT code is where the last two meet. It is the only marking that ties one physical tire back to the plant that built it and forward to the customer driving on it.
The code also changed on April 13, 2025, which was the last day a manufacturer could keep using its old short plant code, so new tires now carry a 13-symbol identification number while tires already in service carry shorter ones. Service teams read both formats on the same vehicle. This page covers what the code contains, where to find it, what US law asks a dealer to do with it, and how technicians capture it without a clipboard.
One boundary first. Everything below applies to tires on passenger cars and light trucks. Heavy commercial vehicles sit under a separate federal rulebook that this page does not cover.
What DOT tire regulations actually cover
For a passenger tire sold in the United States, three federal rules do almost all of the work. FMVSS No. 139 sets performance and marking requirements for radial tires on light vehicles, and it is the reason the letters DOT appear on the sidewall at all. Part 574 defines the identification number and the records a seller keeps. The Uniform Tire Quality Grading Standards add the treadwear, traction, and temperature grades that let a buyer compare one tire against another.
FMVSS 139 also puts the wear markers in the grooves. Paragraph S5.4 requires “not less than six” treadwear indicators around the circumference, set so a person can see when the tire has worn to “one sixteenth of an inch”.
One term causes more confusion than the rest of the rulebook combined. A tire is not DOT approved. NHTSA does not test or approve individual tires. The DOT symbol is the manufacturer’s own certification that the tire meets the applicable federal standard, which Part 574 states plainly: “The DOT symbol constitutes a certification that the marked tire conforms to an applicable Federal Motor Vehicle Safety Standard.” Responsibility sits with the maker, and the agency enforces after the fact.
None of these rules say how much tread a tire needs to stay legal once it is on the road. States set that. California, for example, requires 1/32 in of tread in any two adjacent grooves for an ordinary passenger tire, and raises the figure for snow tires used in a chain control area.
How to read a tire’s DOT code
A DOT code on a new tire is a 13-symbol Tire Identification Number, split into three groups. Read left to right after the letters DOT.
| Group | Symbols | What it tells you | Example |
|---|---|---|---|
| Plant code | 3 | The factory that built the tire. NHTSA assigns it. | A1B |
| Manufacturer’s code | 6 | The maker’s own descriptive code, covering tire characteristics or the brand name owner. | C7D9EF |
| Date code | 4 | Week and year of manufacture. | 2225 |
Put together, a code reading DOT A1B C7D9EF 2225 came out of plant A1B in the 22nd week of 2025.
A DOT code identifies a batch. Four tires built to the same specification in the same plant in the same week carry the same identification number, and that property trips up more inventory systems than any other.
Batching is what makes a recall workable, because the manufacturer can name a plant and a production window instead of chasing individual units. The cost of it shows up elsewhere. A DOT code cannot on its own tell two tires apart, so it fails as a unique key for asset tracking or theft recovery.
The middle group is worth understanding before you build anything around it. Part 574 lets the manufacturer use those six symbols “as a descriptive code for the purpose of identifying significant characteristics of the tire or to identify the brand name owner”. Every maker fills that space differently, and no public master key exists. A decoder will tell you reliably where and when a tire was built, and it will hand you the middle group as raw characters, because their meaning belongs to whoever molded them.
Why some DOT codes are shorter than 13 symbols
Shorter codes are legal, and there are millions of them still rolling. NHTSA standardized the identification number at 13 symbols in 2015 and then gave manufacturers a decade to switch, because the change extended the plant code from two symbols to three and every plant needed a new one. Part 574 put the deadline in writing: “A manufacturer may continue to use a previously assigned two-symbol plant code until April 13, 2025.”
The older format was shorter, and it varied in length, because the size code and the descriptive code were both capped at a maximum instead of set at a fixed length. NHTSA’s own rule describes the result: a full identification number under the old scheme “may be anywhere between 6 and 12 symbols”. Tires stay in service for years, so a technician pulling a car onto the lift in 2026 reads a mixed population, and often finds both formats on the same vehicle after one axle has been replaced.
That has a practical edge for anyone writing software or an inspection checklist. A rule that validates a DOT code by counting characters will throw out perfectly valid legacy codes. Match on the shape of the code and on the trailing four digits, and treat length as information instead of a pass or fail test.
Where the DOT code is, and why you sometimes cannot see it
The full identification number only has to appear on one side of the tire, and federal rules pick the side. Part 574 requires the manufacturer to label the number “on one sidewall”. FMVSS 139 is more specific for tires built since September 2009: the number goes on the intended outboard sidewall, and the other sidewall may carry either the complete number or a partial one.
Read the rule closely, and the partial number turns out to be defined by what it leaves off. FMVSS 139 describes it as every character in the identification number “except for the date code and, at the discretion of the manufacturer, any optional code”. A partial code therefore never carries a manufacturing date, by definition and by design.
Walk around a mounted wheel, and the consequence shows up fast. A technician who cannot find the week and year has usually found the inboard face, and the full marking is on the side turned away. Getting the complete code means turning the steering, reaching behind the wheel, or pulling the tire.
This is the single most common reason a DOT record comes back incomplete, and no amount of process discipline fixes it. The information is not there to read.
What the date code says about tire age
The last four digits give the week and the year the tire was built. Nothing in federal law turns that into an expiry date. NHTSA puts the position carefully: “Some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old, regardless of treadwear.” Those numbers come from the makers, and the agency reports them as advice.
The date code marks the moment the tire left the press. A tire can sit in a warehouse for a year before anyone sells it, and longer than that on a distributor’s rack. So the four digits set the earliest possible age of the tire and say nothing about how long it has carried a load.
Very occasionally a three-digit date code turns up, usually on a spare that has never been used. Older tires used a shorter date code in which the year is ambiguous, and current federal rules require four digits. Anything still carrying three is old enough that pinning down the exact year is the least of its problems.
What the treadwear, traction and temperature grades mean
Next to the DOT code sits a second set of markings that answers a different question. The Uniform Tire Quality Grading Standards require most passenger car tires sold in the US to carry three grades, covering “the relative performance of passenger car tires in the areas of treadwear, traction, and temperature resistance”.
Treadwear is the one people misread. The number is a percentage of a government reference value, and it carries no mileage in it. A tire graded 400 should wear roughly twice as long as one graded 200 under the same test. It compares tires against each other and predicts nothing about how long a specific set will last on a specific car.
Traction runs AA, A, B, C and covers less than most buyers assume. The required consumer wording spells out the gap: the grade “is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics”. Temperature runs A, B, C for heat resistance at speed. All three grades are assigned by the manufacturer under a defined federal test procedure, in the same way the DOT symbol is.
What US dealers have to record when they sell a tire
An independent tire dealer has to register every new tire it sells, and federal rules offer three ways to do it. The dealer picks one.
- Hand the buyer a paper registration form at the point of sale with the identification number and the dealer’s details already recorded on it.
- Record the same information on a paper form and return it to the tire manufacturer within 30 days of the sale, free to the customer.
- Transmit the same information electronically by secure means within 30 days of the sale, free to the customer.
Independent here has a specific meaning. Part 574 defines it as a dealer or distributor whose business is not owned or controlled by a tire manufacturer or brand name owner. Company-owned stores register under different terms.
One point deserves correcting, because a lot of published guidance gets it wrong and so did an earlier version of this page. Electronic transmission sits alongside the two paper routes as an equal option, and federal law stops short of requiring it. The 2015 FAST Act directed NHTSA to write a rule obliging independent sellers to record and electronically transmit registration data at no cost to the customer.
That rulemaking has not been issued. Until it is, the paper routes remain lawful, and any vendor telling you that federal law now mandates electronic registration is ahead of the regulation.
What happens when tire registration records are wrong
Registration failures are enforced through civil penalties, and the ceiling is high. NHTSA‘s current schedule sets a maximum of $27,874 per violation, with $139,356,994 for a related series, published in December 2024. Those figures adjust for inflation each year, so check the current table rather than a number you saw in an article.
The fine is rarely the real cost. A recall only reaches the people whose tires were registered, and the recovery numbers have historically been poor. When the NTSB reviewed passenger vehicle tire safety in 2015, it reported that a tire manufacturer “physically recovers only about 20 percent of recalled tires”, and cited a Michelin survey of independent dealers covering 2010 to 2013 in which fewer than 2 percent of tires sold were being registered.
Both of those figures are more than a decade old. Registration practice has moved on since, though no newer public dataset has replaced them, so treat them as the direction of the problem and not a measure of its size today. For scale on the underlying risk, NHTSA recorded 511 traffic fatalities in tire-related crashes in the United States in 2024.
How to check whether a tire has been recalled
The DOT code is the lookup key, and the search that accepts it belongs to the industry side. The U.S. Tire Manufacturers Association runs a recall lookup at recallinfo.ustires.org where you enter the identification number from the sidewall. NHTSA’s own recall page at nhtsa.gov covers tires too, but it searches by brand and line and returns general results, so it will not resolve a single tire from its code.
Three limits are worth building into the process. The USTMA tool covers recalls by its member companies, which leaves anything from a non-member outside it. The search needs the full number, so a partial code off an inboard sidewall will not resolve. And a recall issued after the check still applies, which is the entire reason the registration record exists: the manufacturer has to reach the owner when the tire is already on the car.
For a service department, that turns the recall check into two separate jobs. One runs at the point of sale and protects the customer standing in front of you. The other runs for years afterward and depends on a registration record that was accurate on the day it was filed.
How service teams capture DOT codes without a clipboard
Reading a DOT code by eye and typing it into a form is the slowest and least reliable step in a tire inspection. The characters are molded black on black; they sit on a curve, they collect brake dust, and half of them are on the side of the tire you cannot easily see. Then there are the confusions that hand transcription always produces: 0 and O, 1 and I, 8 and B. Every one of those goes straight into the registration record and stays there.
Anyline reads the code with the camera already in the technician’s pocket, and the identification step is where speed genuinely counts. Anyline’s DOT capture runs up to 300% faster than manual recording. Discount Tire, which operates almost 1,100 stores across the United States, moved its technicians off pen and paper onto a mobile inspection tool built with Anyline and Zebra Technologies, and now completes a tire assessment in under five seconds.
Our new tire inspection solution is a game-changer for our people and will help further our assurance to our customers that we are taking care of their safety by providing the best possible service and most accurate tire readings.
Being clear about what the capture layer does not do matters more than the speed figure. It reads characters off a sidewall. It does not decide whether a tire has been recalled, and it does not file the registration for you. The record still has to reach the manufacturer through one of the three routes above, and someone still has to run the number against the recall lookup. What changes is that the number in the record matches the number on the tire.
Success Story: Discount Tire
Discover how Discount Tire launched a tire inspection mobile computing solution with Anyline and Zebra Technologies
How tire identification works in the UK and EU
Tires sold in the UK and the EU carry a date of manufacture, and it has nothing to do with the DOT. UN Regulation No. 30 governs passenger car tire approval across both markets, and it requires “the date of manufacture in the form of a group of four digits, the first two showing the week and the last two the year of manufacture”. Same four digits, same meaning, different legal source.
R30 also requires the trade name, the size designation, the load index, the speed symbol and the circled E approval mark. What it leaves out is the plant and batch grouping that the US identification number carries, which is the part that lets a recall be aimed at a production run.
Plenty of tires on European roads carry a DOT code as well, because manufacturers build for a global market and mold both sets of markings. No European rule asks for it.
There is no EU or UK equivalent of the US tire registration form. Recall reach in Europe rests on the obligations that sit with manufacturers and distributors rather than on a customer record created at the point of sale, which is why a European service department has no filing duty when it fits a tire.
Minimum tread depth runs at 1.6 mm across both markets. The EU sets it in the main grooves for cars, vans and light trailers. The UK wording is more exact and worth quoting, because it defines where you measure: at least 1.6 mm “throughout a continuous band comprising the central three-quarters of the breadth of tread and round the entire outer circumference of the tyre”.
Tire age is where the two markets diverge from expectation. No maximum age applies to a car tire in the UK. The ten-year rule that gets quoted in trade press covers goods vehicles over 3.5 tonnes, buses, coaches and minibuses, and it leaves passenger cars alone.
Reading the DOT code with a smartphone
Anyline DOT scanner reads the identification number off the sidewall using the camera in the technician’s own phone or tablet, and writes the characters straight into the inspection record. There is no second device to carry, no clipboard, and no retyping at the counter. The technician holds the phone to the tire, the code appears on screen, and the record ends up carrying the same characters that are molded into the rubber.
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DOT tire regulations: common questions
What is the DOT tire rule?
There is no single DOT tire rule. People asking usually mean one of two things. The marking rule requires every tire sold in the US to carry the DOT symbol and a Tire Identification Number molded into the sidewall. The registration rule requires the dealer who sells that tire to record who bought it. Both sit in 49 CFR Part 574, and they fall on different parties: marking on the manufacturer, registration on the seller.
What are DOT compliant tires?
A DOT-compliant tire is one the manufacturer has certified as meeting the applicable Federal Motor Vehicle Safety Standard. The DOT symbol on the sidewall is that certification. NHTSA does not test or approve individual tires before they go on sale, which is why “DOT approved” is a misnomer. The agency writes the standard, the manufacturer certifies against it, and enforcement comes afterward.
How old should tires be to be DOT?
Age has no bearing on whether a tire carries a valid DOT marking. The certification is made at manufacture and it holds for the life of the tire, and no federal rule in the US sets a maximum age for a passenger tire. NHTSA states that “some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old, regardless of treadwear”. The DOT code is what tells you the age, because the last four digits give the week and year of manufacture.
What is the 7/7 rule for tires?
The 7/7 rule is a consumer maintenance habit with no regulation behind it: check tire pressure every seven days, and inspect the tires before any drive of seven hours or more. No standards body, tire manufacturer or federal rule publishes it. NHTSA’s own guidance runs on a monthly cycle and asks drivers to “check the pressure of all tires, including your spare, at least once a month when the tires are cold”.
How do you read a tire’s DOT code?
A DOT code on a new tire is a 13-symbol Tire Identification Number that splits into three groups. The first three symbols are the plant code, which identifies the factory. The next six are the manufacturer’s own descriptive code. The last four are the date code, giving the week and the year. A code reading DOT A1B C7D9EF 2225 came out of plant A1B in the 22nd week of 2025.
Where is the DOT number on a tire?
The full identification number goes on the intended outboard sidewall, which is the face pointing away from the vehicle. The other sidewall may carry either the complete number or a partial one, and FMVSS 139 defines a partial number as the identification number without its date code. So a technician who cannot find the week and year has usually found the inboard face, where the date is never printed.
Why is my tire’s DOT code shorter than 13 characters?
Shorter codes are legal and common. NHTSA standardized the identification number at 13 symbols in 2015 and allowed manufacturers to keep using previously assigned two-symbol plant codes until April 13, 2025. The older format varied in length, and NHTSA’s rule puts the range at anywhere between 6 and 12 symbols. Those tires stay in service for years, so a shop in 2026 reads both formats, sometimes on the same vehicle.
What do US tire dealers have to record when they sell a tire?
An independent dealer picks one of three routes set out in 49 CFR 574.8. It can hand the buyer a paper registration form at the point of sale with the identification number already recorded on it. It can record the same information on a paper form and return it to the manufacturer within 30 days. Or it can transmit that information electronically by secure means within 30 days. The last two have to be free to the customer, and none of the three is more required than the others.
