How to Read Tire Manufacture Date and When to Replace Old Tires

Every tire sold in the United States carries a Department of Transportation (DOT) serial number molded into its sidewall. Hidden inside that string of letters and numbers is the tire’s manufacture date, down to the exact week and year it left the factory. Most drivers never look at it, yet that four-digit code can mean the difference between a safe commute and a blowout on the highway.

Rubber degrades over time regardless of how much tread remains. A tire sitting in a garage or rolling on a lightly used vehicle can be just as dangerous as one worn to the wear bars. This guide explains exactly how to find and decode the DOT date code, what the major safety authorities say about tire age limits, and how to decide when it is time to replace tires before they fail.

Where to Find the DOT Code on Your Tire

The DOT serial number is embossed on the sidewall of every tire sold in the US, as required by the Federal Motor Vehicle Safety Standard (FMVSS) 109 and 119. The full serial appears on the outboard side of the tire in most cases, though some manufacturers mold only a partial code on the inboard face.

To locate it, crouch beside your vehicle and look at the outer sidewall near the rim. You are looking for a string that begins with the letters DOT, followed by two letters (plant code), two more letters or numbers (tire size code), up to four optional characters (brand-specific data), and finally a four-digit number. That last four-digit group is the manufacture date code.

If you can only see a partial code ending in three digits instead of four, you are looking at a tire made before 2000. Tires from that era used only three digits for the date and should be considered end-of-life regardless of condition.

How to Decode the Four-Digit Week and Year Number

The manufacture date is encoded in the last four digits of the DOT serial. The format is simple once you know the pattern:

• First two digits represent the week of manufacture, from 01 (first week of January) to 52 or 53 (last week of December).
• Last two digits represent the year.

A code reading 2419 means the tire was manufactured in the 24th week of 2019, which falls in mid-June 2019. A code reading 0422 means the first week of February 2022.

Here are a few worked examples to build confidence:

• DOT ending in 1124 = week 11 of 2024 = mid-March 2024
• DOT ending in 3521 = week 35 of 2021 = late August 2021
• DOT ending in 0118 = week 1 of 2018 = early January 2018

Once you decode the date, write it on a piece of tape inside your glove box or photograph the sidewall with your phone so you have a permanent record without crawling under the car again.

What Safety Authorities Say About Tire Age Limits

No single federal regulation currently mandates a maximum tire age in the US for passenger vehicles, but multiple recognized authorities have published guidance that tire professionals and automakers rely on.

• NHTSA (National Highway Traffic Safety Administration) states that tires degrade over time even when stored properly, and recommends that consumers follow automaker guidance and have tires inspected regularly once they reach six years of age.
• Most automakers, including Ford, Volkswagen, and Chrysler, specify in their owner’s manuals that tires should be replaced after six years regardless of tread depth, and that ten years is the absolute maximum service life even if the tire appears serviceable.
• The British Tyre Manufacturers Association and the European Tyre and Rim Technical Organisation (ETRTO) recommend a ten-year maximum, citing rubber oxidation and ozone degradation as the primary failure mechanisms.
• NHTSA’s tire safety resources (available at nhtsa.gov/vehicle-safety/tires) advise inspecting tires older than five years annually for cracks, bulges, and dry rot, even if tread depth is still above the 2/32-inch legal minimum.

The consensus among industry bodies is clear: six years as a practical replacement guideline, ten years as an absolute ceiling. Tread wear alone is not a reliable indicator of a tire’s safety once age becomes a factor.

Signs of Age-Related Tire Degradation to Watch For

Rubber compounds in tires contain antiozonants and antioxidants that slow degradation, but those chemicals deplete over time through UV exposure, heat cycles, and contact with ozone in the atmosphere. When they are exhausted, the rubber begins to crack and harden. Here is what to look for during a visual inspection:

• Sidewall cracking (crazing): Fine cracks in the sidewall rubber, even if they do not penetrate deep, indicate the rubber is becoming brittle. These cracks can rapidly propagate under load.
• Tread groove cracking: Cracks visible at the base of the tread grooves are a sign of advanced degradation and warrant immediate replacement.
• Hardened rubber feel: Press your thumbnail lightly into the sidewall. Fresh rubber has a slight give. Aged rubber feels hard and unyielding.
• Bulges or bubbles: These indicate internal structural failure, often in the belt or carcass, and represent an immediate blowout risk.
• Discoloration: A grayish or faded appearance, especially combined with surface cracking, signals ozone damage.

Any tire showing these signs should be replaced immediately, regardless of its manufacture date or remaining tread depth.

How Storage and Usage Conditions Affect Tire Aging

Two tires manufactured the same week can age at dramatically different rates depending on how they are used and stored. Understanding these factors helps you assess your specific tires more accurately.

• Heat accelerates degradation. Tires in hot climates (the US Southwest in particular) or on vehicles that sit in the sun regularly age faster than the same tire in a cooler, shaded environment. NHTSA notes that higher ambient temperatures significantly reduce tire service life.
• Ozone exposure. Electric motors, fluorescent lighting, and welding equipment all generate ozone. Storing tires near these sources speeds up ozone cracking. Garages with a freezer or electric motor nearby are a common problem.
• UV light. Direct sunlight breaks down rubber compounds. Tires stored outdoors or driven regularly in strong sun degrade faster than garage-kept examples.
• Underinflation and overloading. Running tires below the recommended PSI creates excess heat inside the tire during driving, compounding thermal degradation.
• Long-term storage. Spare tires, especially full-size spares mounted in a compartment under a vehicle or exposed on a truck bed, often age faster than the four driving tires. Always check the spare’s date code, not just its appearance.

A tire on a low-mileage classic car stored in a hot garage for eight years may be more dangerous than a high-mileage tire on a daily driver kept in a cool, shaded parking structure.

How to Check Tire Age When Buying Used or New Stock

Buying tires requires checking the manufacture date, not just the brand and size. New tires sitting in a warehouse or on a shop shelf continue to age, and a tire purchased new that was manufactured two or more years ago carries a shorter remaining service life than one just produced.

• When buying new tires: Ask the retailer for the DOT date code before purchase. A reputable shop will not object. Aim for tires manufactured within the last 12 to 18 months if possible. Reject any new tire more than two years old unless you receive a significant price reduction that reflects its remaining service life.
• When buying a used vehicle: Decode the date code on all four tires and the spare as part of your pre-purchase inspection. Tires often look fine visually but may already be approaching or past the six-year guideline. Factor replacement costs into your offer.
• At lease return or ownership transfer: Fleet vehicles and leased cars sometimes return with tires that look adequate on the tread gauge but are four to six years old. A new owner starting fresh with old tires faces unexpected replacement costs within months.

The US Tire Manufacturers Association (USTMA) supports transparent disclosure of manufacture dates and recommends consumers check the date code at every tire purchase.

Practical Steps to Track and Manage Tire Age

Building a simple habit around tire date tracking can prevent a dangerous and expensive roadside failure.

• Photograph the DOT codes on all four tires and the spare when you buy a vehicle or install new tires. Store the images in a folder on your phone labeled with the installation date.
• Set a calendar reminder for five years after the tire manufacture date (not installation date) to begin annual inspections and start budgeting for replacement.
• Check the spare tire date separately. Compact spare tires (the small temporary spares often called donuts) are typically rated for a single emergency use and a maximum speed of 50 mph. They are not designed for extended driving but they still degrade from age. NHTSA recommends inspecting the spare every time you check your regular tires.
• Do not rely on tread depth alone. The penny test (insert a penny with Lincoln’s head pointing in; if you can see the top of his head, the tread is below 2/32 inch) tells you about wear, not rubber condition. A tire can pass the penny test and still be dangerously old.
• Ask during oil changes. Many service centers check tires visually but do not always decode the date. Ask your technician specifically to report the manufacture date, especially if you are unsure how old your tires are.

Frequently Asked Questions

How old is too old for tires?

Most automakers and tire industry organizations recommend replacing tires at six years from the manufacture date regardless of remaining tread depth, and treating ten years as an absolute maximum even if the tire looks and feels fine. NHTSA advises that tires older than six years be inspected annually by a qualified technician. In hot climates or with poor storage conditions, tires may need replacement even sooner than six years.

Can a tire expire even if the tread looks fine?

Yes. Tread depth is a measure of wear, not rubber health. The polymer compounds inside the tire degrade through oxidation, ozone exposure, UV light, and heat cycles even when the tire is not being driven. A tire with 7/32 inch of tread remaining but manufactured eight years ago may have brittle internal structure and cracked sidewall rubber that puts it at real risk of sudden failure under highway loads or in hot weather.

Where is the tire manufacture date located?

The manufacture date is encoded in the last four digits of the DOT serial number, which is molded into the tire sidewall. Look for the text starting with DOT near the rim on the outer sidewall. The final four digits follow the format WWYY, where WW is the two-digit week (01 to 52) and YY is the two-digit year. For example, 1823 means the 18th week of 2023.

Does the six-year rule apply to spare tires too?

Yes, and spare tires often need extra attention because they sit unused and may be exposed to heat under a vehicle or in a truck bed. The manufacture date on a spare is just as important as on the four driving tires. A compact temporary spare with an eight-year-old date code should be replaced even if it holds air perfectly, because the rubber has aged and may fail under the stress of an emergency situation.

Is there a US law requiring tires to be replaced after a certain age?

As of this writing, there is no federal US law mandating tire replacement at a specific age for passenger vehicles. NHTSA has studied the issue and issued guidance recommending that consumers follow automaker owner’s manual recommendations, which typically specify six years as a replacement guideline and ten years as a maximum. Some state vehicle inspection programs check tread depth and visible condition but do not currently mandate replacement based on date code alone. The absence of a federal mandate does not mean aged tires are safe, only that enforcement falls to individual consumer awareness and manufacturer recommendations.

The Bottom Line

The four-digit DOT date code on your tire sidewall is a very overlooked pieces of safety information on your vehicle. Decoding it takes less than a minute, and knowing your tires’ age allows you to follow the six-year replacement guideline that automakers and tire industry bodies consistently recommend. Tread depth tells you about wear, but only the manufacture date tells you about the rubber’s remaining structural integrity. Check the code, photograph it, set a reminder, and never assume a tire is safe simply because it still has tread left.

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