How to use it
- Find “DOT” on the sidewall followed by 10–13 characters, e.g. DOT HJ YR 3PF 2319. If the last group is missing, look at the other side of the tire.
- Type the last four digits (or paste the whole code) – the tool reads the week and the year.
- Read the production week with its calendar dates, the age in years, months and days, and the colour-coded age advice.
- Check all four tires and the spare; spares are often the oldest tire on the car.
Example
A sidewall reads DOT U2LL LMLR 2319. The last four digits are 23 and 19, so the tire was moulded in week 23 of 2019 – 3 to 9 June 2019. On 20 October 2026 that makes it 7 years, 4 months and 17 days old: past the six-year mark at which several car makers recommend replacement and within the ten-year limit used by tire manufacturers, so it should be inspected for cracking and replaced soon. A code of 408 with a triangle means week 40 of 1998 – a tire that belongs in the recycling bin.
How the date is decoded
DOT PP SS (TTTT) WWYY
│ │ │ └─ week 01–53 and year (2000+). Three digits WWY = 1990s (triangle) or 1980s
│ │ └─ manufacturer’s optional type code
│ └─ tire size code
└─ plant code
week dates: ISO 8601 week numbering (week 1 contains 4 January)The Tire Identification Number is required by US Federal Motor Vehicle Safety Standard 139 and the Federal Register’s TIN rules (49 CFR 574.5): the last group is the date of manufacture as week and year. Manufacturers do not publish how they count weeks, so this tool uses ISO 8601 week dates, which match the usual industry decoders to within a few days. The age is counted from the Monday of that week to today, as whole years, months and days. Codes in the future, impossible weeks (00, 54+) and week 53 in a year that has only 52 are rejected with a message.
Age guidance: NHTSA notes that some vehicle manufacturers recommend replacing tires six years after manufacture and that most tire manufacturers set ten years as the maximum, with annual inspections after five years. Rubber ages through oxidation and heat even when a tire is unused, so storage time counts. The tool colours results green (under 6 years), amber (6–9 years) and red (10 years and over).
Sources: NHTSA – Tires: tire aging and how to read the DOT code, 49 CFR § 574.5 – Tire identification requirements, Michelin – When should I replace my tires? (10-year limit, 5-year inspections).
Age is only one factor: tread depth, damage, repairs and storage matter too. Follow the vehicle and tire manufacturers’ instructions and have tires inspected by a professional if in doubt.
Where to find the code
The DOT code sits in the lower sidewall near the rim, starting with the letters DOT. Since 2000 the date is the last four digits of the string; on tires made in the 1990s it is a three-digit group followed by a small triangle (the 1980s used the same three digits with no triangle). Only one sidewall must carry the full code, so if you see DOT followed by just two or three groups, check the inner side of the tire.
Questions
- How old is too old for a tire?
- Ten years from the production date is the limit used by tire manufacturers and quoted by NHTSA, regardless of tread. Several vehicle makers (including Ford, Nissan and Mercedes-Benz) say six years. From five years on, have the tires inspected every year.
- What does 2319 on a tire mean?
- Week 23 of 2019 – the tire was moulded between 3 and 9 June 2019. The first two digits are always the week and the last two the year.
- My DOT code has only three digits at the end – what year is it?
- A three-digit date means the tire was made before 2000: 408 is week 40 of 1998 if a triangle follows the code, or 1988 if not. Such a tire is well past its service life.
- Does the age start when I bought the tires?
- No. Age counts from the production week on the sidewall. Tires can sit in a warehouse for years, so check the code before buying and ask for stock less than a year or two old.