How to Check a Tire's Date: Reading the DOT Code on Your Sidewall

Every tire sold in the United States carries a manufacturing date stamped directly into the rubber — no special tools required to find it. That date matters more than most drivers realize, because tires age whether they're driven on or not. Here's how to find it, read it, and understand what it means.

Where the Date Is Located

The date code is part of a longer alphanumeric string called the DOT number, which appears on the tire's sidewall. DOT stands for Department of Transportation — it's a compliance identifier required on all tires sold in the U.S.

The full DOT code typically looks something like this:

DOT MA L9 ABCD 2319

The last four digits are what you're after. This is the week and year of manufacture, formatted as WWYW:

• The first two digits = the week of the year (01 through 52)
• The last two digits = the year

So 2319 means the tire was manufactured in the 23rd week of 2019.

How to Find It on the Sidewall

The DOT string is molded into the rubber, usually on the inner sidewall — the side facing the vehicle. On some tires, it appears on the outer sidewall. If you're having trouble spotting it, look for the letters "DOT" and follow the string from there. The four-digit date code always comes last.

🔦 A flashlight helps on tires that are still mounted — the molded text can be shallow and hard to read in low light or if the tire has accumulated grime. Wiping the sidewall clean first makes the numbers easier to see.

Tires Made Before 2000

If you're looking at an older tire, the date code may only have three digits instead of four. For example, 239 would mean the 23rd week of the 9th year of a decade — but which decade is ambiguous without additional context. This format was used before the year 2000. If you find a three-digit code on a tire, treat it as a strong signal that the tire is very old and likely past any safe service life.

Why the Manufacturing Date Matters

Rubber degrades over time through a process called oxidation. UV exposure, heat, humidity, and oxygen all break down the compounds in tire rubber — even when a tire looks fine on the surface. This degradation can lead to:

• Cracking in the sidewall or tread grooves (sometimes called crazing)
• Tread separation, where the tread layer pulls away from the carcass
• Reduced flexibility, which affects grip and handling

The problem is that these changes aren't always visible to the naked eye. A tire can look acceptable and still be structurally compromised.

Industry Guidance on Tire Age 🕐

There is no single universal law in the U.S. that mandates tire replacement at a specific age, but there are widely referenced guidelines from tire manufacturers and safety organizations:

The most conservative guidance — often cited by vehicle manufacturers — is 6 years from the manufacture date, with 10 years as an absolute maximum. Tires that are 10 or more years old from their DOT date are generally considered end-of-life regardless of tread depth.

Variables That Affect How Quickly Tires Age

Not all tires age at the same rate. Several factors accelerate rubber degradation:

• Climate: Hot, sunny regions cause faster oxidation than cooler climates. A tire stored or driven primarily in the Southwest ages differently than one kept in the Pacific Northwest.
• Storage conditions: Tires stored in garages away from sunlight, ozone sources (like electric motors), and extreme temperatures age more slowly than those left outdoors.
• UV exposure: Tires parked in direct sunlight for extended periods break down faster.
• Inflation: Consistently over- or under-inflated tires stress the rubber structure in ways that compound age-related wear.
• Use patterns: A spare tire that has never been mounted still ages. Low-mileage tires on a rarely driven vehicle can still degrade on schedule.

Buying Used or New Tires: The Date Still Matters

When buying new tires, it's worth checking the DOT date — tires can sit in warehouse inventory for months or even years before being sold. A "new" tire with a manufacture date from three years ago has already consumed some of its service life. This is especially relevant when buying tires from discount retailers, online marketplaces, or dealers clearing old stock.

When buying a used vehicle, checking the tire date codes is a standard part of evaluating the car's condition. Four matching dates close together suggest the tires were replaced as a set — a positive sign. Mismatched dates across all four corners may indicate piecemeal replacement history worth understanding.

What the Date Doesn't Tell You

The DOT manufacture date tells you how old the tire is — it doesn't tell you how the tire was used, stored, or whether it's been damaged. A tire can be within its service age and still have issues from road hazards, improper inflation, or misaligned wear. Tread depth, sidewall condition, and any signs of irregular wear are separate considerations from the date code alone.

The date gives you one data point. How that date applies to your specific tires, driving environment, vehicle type, and how those tires have been maintained — that's the part only you and a hands-on inspection can answer.