To read a tire date code, find the DOT Tire Identification Number on the sidewall and interpret its final four digits as week and year. For example, 2423 means the tire was manufactured in the 24th week of 2023. The complete date code may appear only on one sidewall, so inspect both sides.
Key Facts at a Glance
- The final four digits of a modern DOT tire code identify the production week and year.
- The first two digits indicate the manufacturing week, normally 01 through 52, with some years including week 53.
- The last two digits identify the manufacturing year, such as 23 for 2023.
- The full date code may be molded only into the inner-facing sidewall.
- Tire age is measured from the manufacturing date, not the date of purchase or vehicle registration.
- Tread depth cannot prove that an older tire remains structurally safe.
What Is a Tire Date Code?
A tire date code is the four-digit date segment at the end of a modern DOT Tire Identification Number. The code records the calendar week and year when the tire was manufactured, while the preceding characters identify production details such as the manufacturing plant and tire size.
The U.S. National Highway Traffic Safety Administration, or NHTSA, uses tire age as one factor in tire safety guidance because rubber compounds and internal materials can deteriorate with time. Heat, ultraviolet exposure, underinflation, heavy loading, long storage, and repeated flexing can accelerate that deterioration.
The code does not show the exact day of manufacture. A tire marked 2423 was produced during week 24 of 2023, which falls approximately in June, but the code cannot identify whether production occurred on Monday or Friday.
A tire date code is also not an expiration date. The U.S. Department of Transportation requires the identification system for traceability, but federal law does not establish one universal age at which every tire becomes automatically illegal or unsafe. Replacement decisions should combine the code with tire condition, vehicle use, and the tire manufacturer’s guidance.
How Does the DOT Date Code Work?
The DOT date code uses a week-year format: the first two digits represent the production week, and the last two digits represent the production year. Modern tires manufactured from 2000 onward use four digits, while tires made before 2000 may use three digits.
For example:
- 0824 means week 8 of 2024.
- 3722 means week 37 of 2022.
- 5021 means week 50 of 2021.
- 2423 means week 24 of 2023.
The first two characters are not a conventional month number. A code beginning with 24 does not mean June 2024 unless the four-digit sequence is interpreted as week 24 and year 23, as in 2423.
How Do You Convert the Week Into a Calendar Date?
A tire date code identifies a production week, not a precise calendar date. Week 01 generally occurs in early January, and week 52 generally falls in late December, but the exact date depends on the calendar year and the manufacturer’s production schedule.
Some calendar years contain a week 53. Therefore, a final date segment such as 5320 can be legitimate, although the tire manufacturer or tire professional can confirm an unusual code. Do not reject a tire solely because the first two digits exceed 52 without checking the full marking.
| Date code | Manufacturing week | Manufacturing year | Approximate period |
|---|---|---|---|
| 0824 | 8 | 2024 | February 2024 |
| 2423 | 24 | 2023 | June 2023 |
| 3722 | 37 | 2022 | September 2022 |
| 5021 | 50 | 2021 | December 2021 |
How to Read Tire Date Code in Four Steps
Reading the code normally takes 5-15 minutes per vehicle, depending on access to the inner sidewalls. The task requires no special equipment, but a flashlight, phone camera, work gloves, and a tire crayon can make faint or obstructed markings easier to identify.
Before You Start
| Requirement | Typical value |
|---|---|
| Time | 5-15 minutes per vehicle |
| Difficulty | Low, but inner-sidewall access can be restricted |
| Tools | Flashlight, phone camera, gloves, tire brush |
| Cost | $0 at home, $10-$25 for a shop inspection |
| Safety prerequisite | Park on level ground and set the parking brake |
| Inspection condition | Tires cool, vehicle stationary, adequate lighting |
Do not crawl beneath a vehicle supported only by a jack. If the full code is on the inward-facing sidewall, photograph it from a safe position or have a tire shop inspect it.
Step 1: Find the DOT Marking
Look around the tire sidewall for the raised letters DOT. The Tire Identification Number follows the DOT marking and may include letters and numbers molded into the rubber.
The DOT marking can appear near the bead, shoulder, or a sidewall rib rather than beside the tire size. Clean dirt from the sidewall with a dry brush, then use angled light because shallow molded characters can disappear under direct glare.
You may also see separate markings for tire size, maximum load, maximum inflation pressure, traction, temperature, or UTQG treadwear. Those markings are not the date code.
You will know this step worked when: you have located DOT and the alphanumeric string immediately following it.
Common mistake: reading a nearby sequence such as P235/65R17 or 104H as the manufacturing date. Tire size and service-description markings do not identify production age.
Step 2: Isolate the Final Four Digits
Read the last four digits in the DOT sequence and write them down exactly. The final four digits are usually placed in a recessed oval, rounded rectangle, or visually separated block, although the molding style varies by brand.
The earlier characters are traceability information. They may identify the plant, tire size, and manufacturer-specific production characteristics. The full Tire Identification Number can contain more information than the four digits needed to calculate age.
For example, in a simplified code such as DOT ABCD 4K7R 2423, the relevant date segment is 2423, not ABCD, 4K7R, or the first two digits after DOT.
You will know this step worked when: the number has four digits and the final two digits correspond to a plausible year.
Common mistake: selecting the first numeric pair after DOT. Those characters can identify the production plant and do not indicate the tire’s age.
Step 3: Decode the Week and Year
Split the four-digit block into two pairs. Read the first pair as the production week and the second pair as the year.
A code of 3919 means week 39 of 2019. A code of 0625 means week 6 of 2025, not June 2025. Leading zeroes matter, so 0625 must remain a four-digit code.
Calculate age from the production week, not from January 1 of the printed year. A tire made in week 50 of 2021 becomes approximately four years old in week 50 of 2025, even though a simple year subtraction may produce a slightly different result.
You will know this step worked when: you can state both the production week and production year without converting the week into an invented exact day.
Common mistake: treating the first pair as a month. Tire date codes use weeks, so 1224 means week 12 of 2024.
Step 4: Check the Opposite Sidewall
Inspect the inner sidewall if the outward-facing side does not show four final digits. U.S. regulations allow the complete date portion to appear on only one sidewall, while the opposite side may show a partial Tire Identification Number without the date.
This arrangement is common on passenger-car tires, light-truck tires, directional tires, and tires mounted with the full code toward the suspension. Turn the steering wheel to improve access to front tires, but do not remove a tire or place yourself under a raised vehicle solely to read the code.
Compare the same axle or vehicle set only as a cross-check. Matching codes are common, but tires can be replaced individually, so one tire must not be assigned another tire’s age.
You will know this step worked when: every tire has an individually recorded four-digit date segment, or a tire professional has verified the marking.
Common mistake: assuming all four tires were produced in the same week. Replacement tires often create mixed-age sets.
What Do the Other DOT Numbers Mean?
The characters before the final four digits identify the tire within the DOT traceability system, but their exact interpretation depends on the tire’s production era and regulatory format. The first two characters commonly identify the plant, while later characters can identify tire size or manufacturer-specific attributes.
| Marking or segment | Typical meaning | Does it show age? | Example |
|---|---|---|---|
| DOT | Tire Identification Number prefix | No | DOT |
| First two characters after DOT | Manufacturing plant code | No | 4K |
| Middle characters | Tire size or manufacturer attributes | No | 7R |
| Final four digits | Production week and year | Yes | 2423 |
| Tire size marking | Nominal dimensions and wheel diameter | No | P235/65R17 |
| Load and speed rating | Permitted load and speed category | No | 104H |
The exact middle characters should not be decoded from a generic internet chart unless the chart matches the tire’s manufacturer and production era. The date segment is the dependable age reference.
Which Tire Date-Code Formats Exist?
Modern four-digit codes and older three-digit codes are the main formats. A three-digit date code indicates a tire manufactured before 2000, and the code alone cannot reliably distinguish every decade.
Four-Digit Codes From 2000 Forward
A four-digit sequence such as 1818 means week 18 of 2018. The format avoids the decade ambiguity found in older codes because the last two digits identify the year within the 2000-2099 period.
Three-Digit Codes Before 2000
A three-digit code such as 159 means the 15th week of a year ending in 9. The code could refer to 1989 or 1999 unless a small triangle symbol provides additional context.
Any tire with a three-digit date code is at least more than two decades old in 2025. It should not be used on public roads. Arrange professional removal and replacement rather than relying on tread appearance or a collector’s claim that the tire was stored indoors.
Three-Digit Codes With a Triangle
A triangle after a three-digit code was used on some tires to indicate the 1990s. A code such as 159△ generally means week 15 of 1999, while 159 without the triangle could represent an earlier decade.
This historical distinction has no practical effect on replacement. Both formats identify tires that have exceeded the service life of any modern passenger vehicle tire.
How Old Is Too Old for a Tire?
There is no single federal expiration date for every tire, but tire manufacturers commonly recommend professional inspection after five years in service and replacement around 10 years from manufacture, regardless of remaining tread. Michelin states, “Michelin recommends that tires be removed from service 10 years from the date of manufacture,” while also advising regular inspections after five years.
That guidance is not permission to drive a visibly damaged six-year-old tire until year 10. Cracking, bulges, exposed cords, vibration, repeated air loss, impact damage, or a history of severe underinflation can require immediate replacement at a younger age.
| Tire age from manufacture | Appropriate action | Why |
|---|---|---|
| Under 3 years | Check pressure and condition at routine intervals | Age alone rarely determines replacement |
| 3-5 years | Inspect tread, sidewalls, pressure history, and storage condition | Heat and service use can accelerate aging |
| 5-9 years | Arrange at least annual professional inspection | Many manufacturers increase inspection emphasis after five years |
| Around 10 years | Replace, even with usable tread, unless the manufacturer gives stricter guidance | Several major manufacturers use 10 years as a maximum recommendation |
| Over 10 years | Replace promptly and avoid high-speed use until replacement | Internal aging may not appear in tread inspection |
These bands are practical maintenance guidance, not a legal classification. NHTSA notes that tire manufacturers differ in their age recommendations, so the vehicle owner’s manual and tire manufacturer guidance take priority.
Is a Tire Safe If It Has Good Tread?
Good tread does not establish that a tire is safe. Tread depth measures remaining groove material, while aging can affect sidewalls, inner liners, belt adhesion, and the rubber between visible tread blocks.
A five-year-old tire with 6/32 inch of tread may need closer evaluation than a two-year-old tire with 4/32 inch, because age and condition answer different safety questions. Tires exposed to desert heat, coastal sunlight, heavy loads, low inflation, or long stationary periods can deteriorate faster than their tread suggests.
Inspect for:
- Circumferential or radial sidewall cracks.
- Cracks between tread blocks or in the grooves.
- Bulges, bubbles, cuts, or exposed cords.
- Uneven wear that indicates alignment, suspension, or inflation problems.
- Persistent vibration after balancing.
- Repeated pressure loss without a puncture explanation.
- Flat spotting after extended storage.
The date code cannot detect any of these conditions. A professional inspection remains necessary when physical symptoms exist.
When Should You Replace a Tire Based on Use?
Replace a tire before a general age threshold when the tire has structural damage, reaches the legal or manufacturer tread limit, develops severe uneven wear, or cannot maintain correct pressure. Use conditions change the risk profile, so a passenger car, trailer, RV, and performance vehicle should not receive identical maintenance intervals.
| Situation | Additional risk | Practical inspection or replacement rule |
|---|---|---|
| Daily commuter vehicle | Heat cycles, potholes, underinflation | Check monthly and before long trips |
| RV or motorhome | Long storage, heavy load, sun exposure | Inspect before every trip and follow the tire maker’s age limit |
| Trailer | Stationary loading and sidewall stress | Check before towing, including the spare |
| Performance or track vehicle | High temperature and lateral load | Inspect after each event and follow competition-tire guidance |
| Spare tire | Years without visual attention | Include it in annual checks and replace at the same age standard |
Trailer and RV owners should not apply a rigid “replace every five years” rule without checking the tire manufacturer, but earlier replacement can be sensible when storage heat, overload, or ultraviolet exposure is severe. A spare tire may be older than the four tires in use.
Can You Buy a New Tire That Is Already Old?
A tire can be unused yet several years old because manufacturing date and retail purchase date are different. Storage in a cool, dry, dark warehouse is less severe than years of road service, but storage does not reset the tire’s age clock.
When buying tires, request the date codes before installation if the purchase channel allows inspection. A tire made 18-24 months earlier is often commercially accepted as new when properly stored, but a buyer who wants maximum service life should ask for a recent production batch.
For a four-tire purchase, check whether the codes are reasonably close. A difference of a few weeks is ordinary; a difference of several years deserves an explanation, a price adjustment, or a different set.
Keep the invoice and record the installation date. The code establishes manufacture age, while the invoice establishes purchase and service history.
What If the Tire Code Is Missing or Hard to Read?
A missing date code on the visible sidewall usually means the complete code is facing inward, not that the tire lacks a date. A professional tire shop can inspect the inner sidewall without guessing from the tire size or serial characters.
Use this troubleshooting sequence:
- Wipe the sidewall with a dry cloth or soft brush.
- Photograph the DOT area with side lighting and zoom.
- Inspect the opposite sidewall.
- Check the other tires only for possible batch information, not as a substitute.
- Ask the tire retailer or manufacturer to interpret an unusual code.
- Replace the tire if the age cannot be established and the tire appears old, damaged, or unusually weathered.
A non-DOT racing slick, agricultural tire, imported specialty tire, or retread may use a different identification system. A tire intended for public-road use should have markings appropriate to its market and regulatory requirements. Do not infer legality or safety from the absence of a familiar DOT sequence.
What Are the Most Common Reading Errors?
The most common error is reading the wrong number. Sidewalls contain several numeric markings, but only the final four digits of the DOT Tire Identification Number provide the modern manufacture date.
Confusing Tire Size With the Date
A marking such as 225/45R17 describes width, aspect ratio, construction, and wheel diameter. It does not indicate the production month or year.
Reading Only the Outward Side
The full date segment may face the vehicle. A partial DOT sequence on the outer sidewall is normal for some installations.
Treating Week as Month
The first two digits represent a week. Code 0924 means week 9 of 2024, not September 2024.
Assuming Tread Proves Remaining Life
Tread depth does not reveal internal belt separation, ozone cracking, or heat damage. Date and condition must be evaluated together.
Assuming All Tires Match
A vehicle can contain tires from different production years after puncture repairs, rotations, replacements, or previous ownership. Record each tire separately.
One practitioner rule is especially useful: photograph every code during the same inspection and label each image by wheel position. This prevents a rear tire’s date from being mistakenly attributed to the front axle during a used-car purchase.
How Should You Check Tires on a Used Car?
Check all four mounted tires and the spare before buying a used car. Compare the manufacturing dates, physical condition, tread depth, pressure, and wear pattern because an apparently inexpensive vehicle can require four tires immediately.
A sensible inspection record includes:
- Wheel position, such as front left or rear right.
- Full four-digit date code.
- Tire brand and model.
- Tread depth in 32nds of an inch.
- Visible cracking, bulges, or repairs.
- Uneven wear and pressure readings.
- Spare-tire date and condition.
A tire set made six or more years ago should influence the purchase price even when tread remains. A set with mixed brands, mismatched dates, or one replacement tire may indicate prior puncture or alignment issues, so inspect the suspension and wheel alignment rather than treating the date code as an isolated fact.
Does the Date Code Apply to Retreaded Tires?
Retreaded tires can carry identification marks that differ from a new tire’s original DOT date code. The casing’s age, retread date, casing inspection, and retreader identification may all matter, especially on commercial trucks, buses, and certain trailers.
Passenger-vehicle owners should ask a qualified tire professional to identify whether a tire is new, retreaded, or repaired. The date of a new tread application does not necessarily make the underlying casing new. A retreaded tire requires casing-specific evaluation.
What Should You Do After Reading the Code?
Record the date code, calculate the tire’s age from the production week, and compare that result with the tire manufacturer’s service guidance. Then inspect inflation, tread, sidewalls, repairs, wear, and vehicle loading before deciding whether to keep or replace the tire.
Replace a tire promptly when it has a three-digit date code, is near or beyond the manufacturer’s maximum age recommendation, or shows cracking, bulges, exposed cords, severe vibration, or repeated pressure loss. Do not use a date code as a substitute for a complete tire inspection.
Frequently Asked Questions
Is DOT the same as a tire expiration date?
No. DOT identifies the tire for regulatory traceability, and its final digits show the manufacturing week and year. The DOT system does not create one universal expiration date for every tire. Tire manufacturers publish their own age recommendations, while condition, use, storage, inflation, load, and damage can require earlier replacement.
Where is the date code on a Michelin, Goodyear, or Bridgestone tire?
The date code is part of the DOT Tire Identification Number on the sidewall of Michelin, Goodyear, Bridgestone, and other road tires sold in the United States. The complete four-digit segment may face inward. Search for DOT, then read the final four digits rather than a nearby size or load marking.
How many years can tires sit in storage?
Storage duration depends on temperature, humidity, sunlight, ozone exposure, and whether the tire carried a vehicle load. Proper storage slows deterioration but does not erase the manufacturing date. Ask the tire manufacturer for its storage policy, and inspect any stored tire for cracking or deformation before installation.
Can I drive on a tire with a date code from 2018?
A 2018 tire is approximately seven or eight years old in 2025 or 2026, depending on its production week. Driving suitability depends on the manufacturer’s guidance and physical condition. Arrange a professional inspection, and replace the tire if it has cracking, damage, poor pressure retention, severe wear, or an age recommendation that has been reached.
Does rotating tires change their age?
No. Tire age continues from the manufacturing week regardless of rotation, mileage, tread position, or installation date. Rotation can improve wear distribution, but it cannot reverse rubber aging or extend a manufacturer’s maximum recommended service period beyond its stated limit.
Should the spare tire be replaced with the other tires?
The spare tire should be inspected and dated separately because it may have spent years unused in a trunk, underbody carrier, or cargo compartment. Replace it when it reaches the manufacturer’s age limit or shows damage, cracking, pressure loss, or unsafe storage-related deterioration.
The Bottom Line
To understand how to read tire date code, locate DOT, find the final four digits, and read them as production week followed by production year. Check both sidewalls, record every tire separately, and treat the result as one part of a safety assessment. Replace aged or damaged tires according to manufacturer guidance, not tread depth alone.
