How to read a tire DOT date code

Decode a tire's four-digit DOT date code in seconds, with three worked examples, what a partial code on one sidewall means, and how to log it.

The four digits

2319 doesn't look like much stamped into rubber. Read correctly, it tells you exactly how old that tire is: week 23 of 2019. The full DOT code runs longer than that. It starts with "DOT," then a two- or three-character plant code, then a string for size and brand, and finally a four-digit date. The date is the part that matters for age, and it always reads week first, year second: WWYY.

Take 4821. That's week 48 of 2021, so the tire came off the line in late November of that year. Or 0517: week 5 of 2017, a tire that was already years old before a customer ever asked about it. Here's the pattern laid out plainly.

Learn the order once and you won't need the table again. Week, then year. Always four digits, in that order, no exceptions.

Why one sidewall might show less

Manufacturers only have to stamp the full code, date included, on one side of the tire. FMVSS 139, the standard for new radial tires on light vehicles, puts it on the intended outboard sidewall, the side meant to face out, for tires made on or after September 1, 2009. Older tires, tires outside that standard, tires with no set outboard side, and tires mounted the other way around can still hide the full code on the side facing the car. What you see from the curb might be a partial code: plant and size, no date at all. That's normal. It isn't a defect and it isn't the shop's mistake.

If the date isn't on the side facing you, check the other side before assuming it's missing. On a mounted tire, that means a light and a mirror under the car, or breaking the bead to spin it around. For a take-off sitting in the back, or anything still on the rack, just flip it over. Takes a few seconds either way, and it beats guessing.

This trips up new hires more than anything else about the DOT code. They see "DOT U2AB 5R17" and no date, assume it's missing entirely, and either skip logging it or guess at an age from how worn the tread looks. Worn tread and tire age aren't the same thing. A tire can look rough at three years or clean at eight. Always go find the date instead of estimating it.

Tires stamped before 2000

Older tires used a three-digit code instead of four: two digits for the week, one for the year. There was no reliable way to tell the decade from the code alone. A tire stamped "236" could be week 23 of 1996 or, on paper, 1986. It doesn't matter which anymore. Any tire carrying a three-digit code is now decades old.

That tire should not be on a customer's car. It shouldn't be on your shelf either. Refuse it and move on to the next one.

Plant codes exist, but skip them

The first two or three characters right after "DOT" identify which plant built the tire. That information is public and decodable, but it isn't something you need memorized to work the counter. What matters for grading, pricing, and refusal decisions is the date, not the factory. A customer might ask where a tire was made out of curiosity, and that's fine to look up. It rarely changes what you actually do with the tire once it's in your hands.

Some techs get hung up trying to identify a plant from memory and waste time doing it. Don't bother. Read the date, log it, move to the next tire.

Brand and size codes sit in the middle of the string, between the plant code and the date, and they can look like a jumble of letters and numbers at first. You don't need to decode those either for day-to-day grading. The sidewall already spells out brand and size in plain text elsewhere, so the DOT string's middle section is mostly useful to the manufacturer, not the shop floor.

When you do need the plant: NHTSA's lookup

Sometimes the factory does matter. Say a customer wants to know who really built a store-brand tire. NHTSA runs a free lookup for that: open the Manufacturer Information Database (MID) on its vPIC site at vpic.nhtsa.dot.gov/mid, go to the "Equipment Plants" search, choose Tires as the equipment type, and type the plant code into the DOT Code box. It returns the manufacturer and the plant behind that code. The help text says the DOT Code field "applies to both New and Old DOT code," which matters for the next point.

Plant codes changed length. Under 49 CFR 574.5 the plant code is three symbols, assigned by NHTSA, and it's the first group of the tire identification number. Manufacturers that held older two-symbol codes could keep using them until April 13, 2025. So a tire from a few years back may show two characters after "DOT" and a newer one three. Both are real. Neither one is a misread.

That adds up to the 13 symbols 574.5 requires on new tires. Retreaded tires get a shorter number of seven symbols, with the "R" for retread marked separately.

The full TIN also matters past age and origin. Tires get recalled too, and NHTSA's recall search covers them. For what the registration rules ask of a shop that sells new tires, see tire registration, recalls and the TIN.

Logging the DOT on a used tire

Log the date on every used tire that comes in before it touches the rack, not after. You don't need the whole string, just the four digits and enough of the rest to match it back to the sidewall if a customer ever asks. Put it on the tire in chalk and again in the record, right next to size, tread depth, and where it came from.

It takes ten seconds. And it answers the age question before anyone has to ask it out loud, which matters more than it sounds like it should when a customer is standing at the counter deciding whether to trust a used tire on their kid's car.

A photo can handle this step. In DuroBay, the tire shop inventory app we build, a picture of the sidewall reads size, brand, model, and DOT straight into the add-tire form, so nobody's squinting at four tiny digits with grease on their hands. For how the rest of that sidewall breaks down, see our guide on how tire sizes work, and for what the tread numbers mean once a tire's on the rack, check the tread depth chart.