Vehicle · Tire age
Tire DOT code decoder.
Type the code from your tire sidewall, or just its last four digits. You get the week and year the tire was made, how old it is today, and where that sits against the six-to-ten-year guidance. It runs in your browser; nothing you type is sent anywhere.
Inputs
Result
Enter the code from the tire and press Decode.
How to read a tire DOT code
Look on the sidewall for the letters DOT followed by a string of letters and numbers. That string is the Tire Identification Number, or TIN. US federal rules (49 CFR 574.5) require it to be molded into new tires. The last four digits are the date code, and that is the part that tells you how old the tire is.
The date code
- First two digits: the week of the year. Week 01 is the first full calendar week, running Sunday through Saturday. The final week of a year may include up to six days of the next year.
- Last two digits: the last two digits of the year of manufacture.
- Three digits instead of four: an old code from before the four-digit date code was adopted. The single year digit does not say which decade, so treat the tire as more than 25 years old.
Worked example
The rule itself gives the example: 0109 means the tire was made in the first full calendar week of 2009, the week beginning Sunday, January 4, 2009 and ending Saturday, January 10, 2009. January 1, 2009 was a Thursday, so the first full Sunday-to-Saturday week starts on the 4th. Press “Try the CFR example” to see the decoder do it, with the age worked out for the date you pick.
The rest of the code
On a current tire the full TIN has 13 symbols: a 3-symbol plant code assigned by NHTSA to the manufacturer, a 6-symbol manufacturer code, and the 4-digit date code. Older tires used a 2-symbol plant code, up to 2 symbols for size and up to 4 optional symbols before the date. The manufacturer code is a private record the maker keeps, so only the manufacturer can say what it means. This tool splits the groups and does not translate them.
When to replace a tire
No federal rule sets a maximum age for a passenger tire. NHTSA notes that some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old regardless of treadwear. The result labels the tire against that range:
- Under 6 years: inside the range manufacturers describe. Age alone is not a reason to replace it. Keep checking tread, sidewalls and pressure.
- 6 to under 10 years: in the window where some manufacturers recommend replacement. Have a tire shop inspect it and check your vehicle manual and tire maker for their advice.
- 10 years or more: past the upper end of that guidance. Most guidance says replace it, whatever the tread looks like.
These bands are guidance, not law. Storage, heat, load and damage change how a tire ages, so a younger tire can still be unsafe.
Limits of this tool
- It checks format and works out a date. It cannot tell whether a code was actually issued to a real tire.
- It does not name the manufacturer. NHTSA assigns plant codes, but this page does not include a copy of its list because it could not be verified as current. Ask the tire shop or the manufacturer.
- The age is counted from the first day of the manufacture week, so it can read a few days older than the exact build date.
- A tire sidewall can show a full TIN on one side and a shorter code with no date on the other. Check both sides.
Sources
- 49 CFR 574.5, Tire identification requirements (eCFR, text checked October 1, 2026): TIN structure, date code, Sunday-to-Saturday week definition, the 0109 example and the authorized symbols.
- NHTSA, Tire Identification and Recordkeeping, 80 FR 19560 (April 13, 2015): records that the date code was originally three symbols and was expanded to four, citing 64 FR 36807 (July 8, 1999).
- NHTSA, Tires (page text read October 1, 2026 from an Internet Archive copy): some vehicle and tire manufacturers recommend replacing tires six to 10 years old regardless of treadwear.
Cite this page: TNAADO Tools, “Tire DOT Code Decoder,” tools.tnaado.ca/calculators/general/tire-dot-code-decoder/, rule checked against 49 CFR 574.5 (eCFR) on October 1, 2026.
Tire DOT code FAQ
Where is the date on a tire?
On one sidewall, after the letters DOT, is a Tire Identification Number (TIN). The last four digits are the date code. Some tires carry the full code on only one side, so check both sidewalls. The other side often shows a shorter code with no date.
How do I read the four-digit date code?
The first two digits are the week and the last two are the year. 0109 means week 1 of 2009. Under 49 CFR 574.5, week 01 is the first full Sunday-to-Saturday calendar week of the year, so 0109 is the week of Sunday, January 4 to Saturday, January 10, 2009.
How old is too old for a tire?
There is no federal age limit for passenger tires. NHTSA says some vehicle and tire manufacturers recommend replacing tires that are six to 10 years old regardless of treadwear. Treat six years as a prompt to have the tire inspected and to check your vehicle manual and tire maker, and ten years as the point most guidance says to replace it. This is manufacturer guidance, not a legal rule.
What if my date code has only three digits?
Tires made before the four-digit code was adopted used three digits: two for the week and one for the year. One digit repeats every ten years, so the decade is not stated. Any tire with a three-digit code is more than 25 years old and should be replaced.
What do the other letters and numbers in the DOT code mean?
On a current 13-symbol TIN the first three symbols are the plant code NHTSA assigns to the manufacturer, the next six are a manufacturer code (often size, type or brand owner, and only the manufacturer's records explain it) and the last four are the date. Older codes used a two-symbol plant code, up to two symbols for size and up to four optional symbols. This tool does not name the manufacturer because it does not carry NHTSA's plant-code list.
Does a valid-looking code prove the tire is genuine or safe?
No. The decoder checks the format and works out a date. It cannot confirm the code was issued to a real tire, that the tire is undamaged, or that it was stored properly. Cracks, bulges and uneven wear matter more than age alone.
Does the spare tire count?
Yes. A spare ages like any other tire even if it has never touched the road, so check its date code too.
Is the code I type sent anywhere?
No. The decoding runs in your browser and nothing is transmitted or stored.
What this checks, and what it does not
This decoder checks the format of a tire code and reads the date from it. It does not confirm the code was issued to a real tire, and it does not assess the condition or safety of a tire. The six and ten year bands are manufacturer guidance reported by NHTSA, not a legal limit. For a safety decision, have the tire inspected by a qualified tire shop.