Find the DOT marking first
- Find the DOT marking on the tire’s sidewall. Its final four digits give the manufacturing week, then the year.
- Use that date to work out age, then consider wear, condition and performance before deciding whether to keep using the tire.
If you’re staring at sidewall numbers without finding a date, we’d locate the DOT Tire Identification Number first, because that’s where the manufacturing date belongs. You’re looking for the end of that marking, so you can leave the other sidewall specifications alone.
Look on both sides of the tire if you haven’t found the number. The Tire Identification Number, shortened to TIN, may not appear on both sides. NHTSA’s tire-age guidance (opens in a new tab) makes this a useful next check when the side facing you hasn’t supplied the date.
Turn four digits into a week and year
Take the final four digits together and split them into two pairs. Read the first pair as the week of manufacture and the second pair as the year. Keeping the pairs separate helps you read the code as a manufacturing period instead of a familiar month-and-year date.
For example, 0308 means the third week of 2008. The leading zero belongs with the 3, giving week 03, while 08 identifies 2008. That gives you a week within a year, rather than an exact calendar day to put on a birthday reminder.
To work out elapsed age, count forward from that manufacturing week and year to the present. Subtracting the manufacturing year gives you a starting point, then the week tells you whether the anniversary has passed. Keep the manufacturing date as your reference even if you bought or fitted the tire later.
A Michelin example you can match to your tire
On Michelin passenger vehicle tires, locate the DOT code on the sidewall and focus on its final four digits. In Michelin’s worked example (opens in a new tab), a code ending in 3520 means manufacture during the 35th week of 2020: 35 supplies the week, and 20 supplies the year.
Michelin gives two more examples that help when you’re comparing tires of different ages. A date code of 4714 means the 47th week of 2014, while 2524 means the 25th week of 2024. Compare the year pair first to establish which manufacturing date came earlier.
If you’re checking a used vehicle or tires that have been in storage, read the date on each tire you’re assessing. Michelin specifically recommends checking the manufacturing date in those situations. Keep each four-digit reading beside its decoded week and year so you can refer to the actual manufacturing period when discussing age.
Low mileage still leaves room for aging
A car that covers little mileage still deserves attention to tire age. NHTSA identifies low annual mileage and infrequently driven vehicles, including collector cars, as situations where aging can become a concern. Plenty of time can pass while the vehicle sees relatively little use.
Aging involves changes to the rubber and other tire components over time, influenced by service, storage and environmental conditions. Sunlight, warmer climates, poor storage and poor maintenance contribute, too. NHTSA identifies the more southern parts of the Sun Belt as an area where tire aging is a greater concern.
Age and a reassuring appearance alone cannot establish that a tire is safe to use; consider the date alongside wear, condition and performance. Michelin explains that heat cycles, UV exposure and ozone can degrade rubber in ways you won’t see on the surface, which is why a visual check has limits.
Use the recommendation for your tires and vehicle
NHTSA reports that some vehicle and tire manufacturers recommend replacement at six to ten years old, regardless of treadwear. That range describes different manufacturers’ recommendations. Apply the guidance for your tires and vehicle when deciding what the date means for replacement.
As tires age, they become more prone to failure. The manufacturing date therefore matters even when your immediate reason for checking is simply a used-car purchase or a tire that still has tread. It gives you the age reference needed to apply a manufacturer’s recommendation.
Michelin describes tire lifespan as the result of several factors, including design, driving habits, climate, road conditions and maintenance. For your decision, keep the age recommendation alongside those service conditions. A tire’s time in use and the conditions it has experienced matter as well as the number you decoded.
Michelin’s five-year inspection wording needs care
Michelin’s replacement guidance (opens in a new tab) calls for a thorough inspection by a trained tire professional at least annually after five years of service. It also describes this starting point as five years of use. Those inspections can reveal aging or damage that isn’t immediately visible.
There’s a timing distinction to keep in view. Michelin’s sidewall-marking guidance (opens in a new tab) discusses the manufacturing date, then recommends a close inspection after five years and replacement by ten years from that date. Its inspection wording therefore uses a manufacture-date context, while the replacement guidance uses service or use.
Keep the manufacturing date and time in service separate when arranging an inspection. We’d follow the earlier applicable inspection point because Michelin’s wording uses both starting points, and the purpose is to catch aging or damage you may not see. Don’t postpone an inspection already due under either wording.
Michelin’s ten-year recommendation includes spares
As a precaution, Michelin recommends replacement ten years after manufacture (opens in a new tab), regardless of remaining tread depth or apparent condition. That recommendation includes spare tires. For the 3520 example, the ten-year point falls in the 35th week of 2030.
For original equipment tires, Michelin instructs you to follow the vehicle manufacturer’s replacement recommendations. Keep that instruction with the ten-year guidance when checking the tires supplied with your vehicle, so your decision reflects the vehicle maker’s recommendation as well.
Spare tires deserve attention because they age and seldom get replaced. Don’t use a spare as a routine replacement for worn tires. NHTSA allows an emergency exception for a full-size spare, such as replacing a flat tire, while warning against making it the regular replacement for a worn one.
Wear, damage or performance problems change the next step
Bring the date reading back to the tire in front of you. Wear and damage can require you to stop using it before an age-based replacement point arrives. A newer manufacturing year leaves those condition checks just as relevant to your next decision.
If a tire fails to maintain proper inflation pressure, makes noise or causes vibration, consult a tire service professional (opens in a new tab). Tell them which performance change you’ve noticed, along with the manufacturing date you read, so the conversation covers both age and what the tire is doing.
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