How to Read a Tire's Manufacture Date (DOT Code Decoded)

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How to Read a Tire's Manufacture Date (DOT Code Decoded)

May 26, 2026 Prince Tires

The DOT date code is the four-digit number on every tire's sidewall that tells you exactly when it was manufactured. Most Calgary drivers have never noticed it, and many tire shops don't volunteer the information when they sell you "new" tires that have been sitting in a warehouse for two years. Reading the DOT code yourself takes thirty seconds and can save you from buying or driving on tires that are already past their service life. Here's how to read a tire's manufacture date, why it matters more than tread depth in some cases, and the rule for when age — not wear — should drive the replacement decision.

What the DOT Code Actually Is

"DOT" stands for Department of Transportation, and every tire sold in North America carries a code that begins with the letters DOT followed by a series of letters and numbers identifying the manufacturer, plant, tire size, and date of manufacture. The last four digits are the date stamp: the first two are the week of the year, and the last two are the year itself.

So a DOT code ending in "2823" means week 28 of 2023 — roughly mid-July 2023. A code ending in "0526" means week 5 of 2026 — late January 2026. The full DOT code can be 9 to 13 characters long, but only those last four digits are the manufacture date. The Tire and Rubber Association of Canada publishes a guide on this if you want the full breakdown.

If you're new to reading tire markings in general, our breakdown on how to read a tire size walks through the rest of the sidewall information.

How to Read the Date in 30 Seconds

Find the DOT code on the sidewall. It's usually printed in a recessed section, often near the bead area where the tire meets the rim. On many tires it's only on one side — if you can't find it on the outer sidewall, check the inner sidewall.
Locate the four-digit code at the end. Right after the DOT prefix and a string of letters/numbers, you'll see four digits.
Read the date. First two digits = week of the year. Last two digits = year. Done.

Examples to make it concrete:

3424 = week 34 of 2024 = late August 2024
0125 = week 1 of 2025 = early January 2025
5023 = week 50 of 2023 = mid-December 2023

If your tire shows a three-digit code instead of four, the tire was made before 2000 (different format) and absolutely needs to be replaced regardless of how it looks.

Why Tire Age Matters Independent of Tread

Rubber degrades over time even when a tire is sitting unused. Heat cycles, UV exposure, oxygen, and ozone all break down the long-chain polymers that give rubber its grip and flexibility. After about six years from manufacture, even an unused tire stored well has lost meaningful elasticity, and the risk of internal cracking and sudden failure climbs sharply.

The widely accepted rule from manufacturers and tire safety organizations: replace passenger tires by six years from manufacture date, regardless of tread. Some manufacturers extend this to ten years for tires kept in ideal storage and rotated regularly, but six years is the conservative number most North American shops work to.

This is why the DOT date matters when you're buying tires. A tire on a shop shelf with 11/32" of tread looks brand new — but if it was made in 2019 and you buy it in 2026, you're already most of the way through its service life. Always ask the shop for the DOT date on tires you're considering buying. Reputable shops will tell you up front and won't sell you a tire more than 18 months old as new.

Calgary-Specific Reasons to Care

Three reasons the DOT date matters more here than in milder climates.

1. UV exposure on stored winter tires. Many Calgary drivers store winter tires in a garage that gets sunlight through windows. UV is brutal on tire rubber. A set of winters stored five summers in a sunny garage will be at the end of life sooner than the same set stored in a dark basement. Our breakdown on how to store winter tires the right way covers the storage variables.

2. Freeze-thaw stress. Calgary's repeated freeze-thaw cycles flex tire rubber more than a steady-cold or steady-warm climate would. Rubber that's flexed through enough freeze-thaw events develops micro-cracks earlier than in milder regions.

3. Long Calgary tire lives. Many Calgary drivers run lower annual mileage than the national average — meaning their tires can hit six years old with full tread still on them. The DOT date check is the only thing that catches this. Pair it with the toonie test for a complete picture, and check the top 5 signs your winter tires are done for what to look for visually.

DOT Date Code FAQs

How old is too old for a tire?
Six years from manufacture is the standard replacement age regardless of tread. Some manufacturers say up to ten years if storage is ideal, but for Calgary conditions six is the safe number.

Why does only one of my tires have the DOT code visible?
Manufacturers only legally need to print the full DOT code on one sidewall. The inner sidewall often has it. The other side may have a partial code without the date.

Is it legal to sell tires older than six years as new?
Yes, in most jurisdictions including Alberta. There's no maximum age limit on what can be sold as new. That's why you have to ask.

Should I worry about the DOT date when buying a used vehicle?
Yes — read the DOT date on all four tires (and the spare) during the pre-purchase inspection. Tires older than six years should be priced into the deal as a near-term replacement cost.

What if my new tires have different DOT dates?
That's fine as long as all four are current. Manufacturers don't make all four tires for your set on the same day. A few weeks' difference is normal.

Free DOT date check on your existing tires

Not sure how old your tires are? Swing by and we'll read the DOT codes on all four (plus the spare) and give you a straight answer on whether replacement is overdue. Five minutes, no charge.

Prince Tires
111 42 Ave SW, Calgary, AB
(403) 452-4283
Book your appointment

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