How to read a tire date code
Four numbers on the sidewall say the week and the year the tire was built. 2319 is week 23 of 2019. Tread depth says how much is left; this says how long it has been in the world, and the two often disagree.
Tire makers give different advice on age, so many shops simply note the code and talk it over with the customer. This page says where the number is and how to read it. What to do about an old set is your call, with the tire in front of you.
Where it is on the tire
- Look for the letters DOT on the sidewallEvery tire built for sale in North America carries it. Follow the raised lettering round from the brand name — it is moulded into the rubber, the same colour as everything else, and easiest to find by running a thumb along it rather than by looking.
- The code runs on from DOTA run of letters and numbers: the plant that built it, the size, a code the manufacturer uses, and then the part you want — the last four digits, on their own.
- Only one side carries the full codeThis is the part that wastes time. In practice only one sidewall carries the complete code, so the side facing you may show the DOT run with the last four digits missing. If you cannot see four digits at the end, look at the other side of the tire — on a mounted wheel that means the inboard face, which is why this is a job for when the tire is off the car.
What the four numbers mean
- The first two are the weekIn 2319, the 23 is the twenty-third week of the year — the week the tire came out of the mould. Weeks run 01 to 52, or 53 in some years, so anything outside that is a misread.
- The last two are the yearIn 2319, the 19 is 2019. Four-digit codes came in around 2000, so there is no ambiguity about the century: 19 is 2019 and not 1919.
- So 2319 is week 23 of 2019Early June 2019. That is when the tire was built, which is not the same as when it was sold or when it went on the car — a tire can sit in a warehouse for a season before anybody drives on it.
- Three digits means it is from before 2000Older tires carry a three-digit code, where the last digit is the year within that decade. If you are holding one of those, the age is not the thing in question any more.
Writing it down, once
- Read it when the tires are off the carAt the changeover, with the set in your hands and both sidewalls reachable. It takes a few seconds a tire and it is the only time in the year it is easy.
- One code for the set, unless they differMost sets were bought together and carry one code. A set with a tire replaced on its own genuinely differs, and it is worth writing down the odd one — the set is as old as its oldest tire.
- Write it where the next person will lookOn the storage ticket, in the book, or in whatever holds the record of the set. A reading taken and not written down is a reading somebody takes again next season, kneeling on the same cold floor.
The questions shops ask about it
How old is too old?
Tire makers give different advice on age, so many shops simply note the code and talk it over with the customer. Many work to a rule of thumb somewhere around six years and treat it as a conversation rather than a rule — the tire in front of you, how it has been stored, and what the tread says. That is a judgement for the shop, not something a website can decide for you.
Does tread depth tell me the same thing?
No, and they often disagree. Tread says how much is left; the date says how long the tire has been in the world. A set that has done eight thousand kilometres over six winters has most of its tread and most of its life behind it, and a set two years old and driven hard is the opposite.
The sidewall facing me has no four-digit code. Is that a problem?
No. Only one sidewall carries the complete code, so the other often ends after the plant and size codes. Turn the tire over.
Is the date code the same as the date it was sold?
No. It is when the tire was built. A tire can sit in a warehouse or on a rack for a season before it is fitted, so a new set can carry a code a year or two old.
What Treadstock does with it
If you are already writing the code on a ticket, this is why it is worth having it in the book.
- Put it in when the set goes away. One box on the intake screen, four numbers, and the four boxes are there for the set whose tires were not all bought together.
- The set’s screen says how old they are — in years, from the oldest of the four — so whoever is at the counter in April has the answer without the tire in their hands.
- The low-tread list says it too, beside the depth, and marks a set at 6 years as getting old. It is a flag with the number attached, not a verdict: the shop decides.
- It comes out in the export, with the codes as they were read and the age worked out on the day you run it.
While the tires are off the car
Two more jobs worth doing in the same ten minutes.