Tire Age (DOT) & Pressure by Terrain
Decode the DOT date code to find how old a tire really is, and what pressure to run on sand, rock, snow and gravel.
Paste the whole code or just the last four digits — that group is the date, and it is the only part this needs.
How to read a DOT code
The date is the last four digits: two for the week and two for the year.
5107 is the fifty-first week of 2007. Everything before it identifies the
plant, the size and the manufacturer's own codes, and none of that tells you anything
about age.
Codes with only three digits predate 2000. There is no way to tell which decade they came from, and it does not matter — a tire moulded in the last century is far past anything anybody should be driving on.
What age means
| Age | Verdict | What to do |
|---|---|---|
| under 5 years | Current | Nothing to do on age grounds. Inspect for damage and wear as normal. |
| 5–6 years | Worth watching | Approaching the point where several vehicle manufacturers recommend replacement regardless of tread depth. Start checking the sidewalls for fine cracking. |
| 6–10 years | Inspect it properly | Past the six-year mark that many vehicle manufacturers use. Rubber hardens and cracks with age whether the tire is driven or not, so tread depth alone no longer tells you it is sound. Have it looked at by someone who will actually take it off the rim. |
| 10 years and up | Replace it | Ten years is the outer limit most tire manufacturers publish, and it applies regardless of tread depth or how little it has been used. That includes the spare, which is usually the oldest tire on the vehicle by a wide margin. |
There is no federal expiry date on a tire. These bands reflect what vehicle manufacturers and tire manufacturers publish, and they differ — six years is a common vehicle-maker recommendation, ten a common tire-maker limit. Neither is a law and both are worth knowing.
Things worth knowing about age
- The date is the last four digits: two for the week, two for the year. 5107 is the fifty-first week of 2007.
- On many tires the full DOT code is moulded on one sidewall only. If you cannot find a date, look at the other side before deciding it does not have one.
- Age matters independently of tread. Rubber oxidises and hardens whether the tire is driven or parked, which is why a trailer tire with full tread can fail on its first trip of the season.
- The spare is almost always the oldest tire on the vehicle, and it is the one nobody checks. It is also the one you find out about at the worst possible moment.
- A "new" tire that has sat in a warehouse for four years is four years old. The date code is the manufacture date, not the sale date, and it is worth reading before you buy.
Pressure by terrain
Air back up before pavement
This is the step people skip and it is the one that matters. A tire at trail pressure on tarmac flexes the sidewall constantly, and that flexing makes heat — heat is what actually destroys tires, far more than any impact. Carry a compressor and airing down becomes a decision rather than a commitment.
Below about 12 psi a tire can unseat from the rim under side load. Beadlock wheels exist for exactly that reason, and without them the lower figures above are a floor to approach carefully rather than a target to aim at.
Things worth knowing about pressure
- Air down for grip, then air back up before pavement. Low pressure on tarmac builds heat in the sidewall, and heat is what destroys a tire — this is the step people skip and it is the one that matters.
- Below about 12 psi a tire can unseat from the rim under side load. Beadlock wheels exist precisely for that, and without them the low numbers on this page are the floor rather than a target.
- Airing down lengthens the contact patch far more than it widens it. That is why it helps so much in sand, where a long footprint floats instead of digging a hole.
- Carry a way to reinflate. A compressor turns airing down from a commitment into a decision, and without one the drive home is the risky part of the day.
- The number on the sidewall is the tire’s maximum cold pressure, not a recommendation. The vehicle door placard is the recommendation, and the two are frequently far apart.
How to use
- Paste the DOT code from the sidewall, or just the last four digits.
- Read the age and what that age means for the tire.
- Set your street pressure to get terrain figures scaled to your vehicle.
Frequently asked questions
How do I read a tire date code?
The last four digits of the DOT string are the date: two for the week and two for the year. So 5107 is the fifty-first week of 2007. Everything before it is plant, size and manufacturer coding, and none of it indicates age.
What if there are only three digits?
It is a pre-2000 tire. Three-digit codes cannot be dated to a decade, and it does not matter — anything moulded in the last century is long past being safe to drive on.
When should a tire be replaced on age alone?
Many vehicle manufacturers say six years and most tire manufacturers publish ten as the outer limit, regardless of tread depth. There is no federal expiry date, so the honest answer is that the two industries disagree and both figures are worth knowing.
Why does age matter if the tread is fine?
Rubber oxidises and hardens whether the tire is driven or parked. It is why a trailer tire with full tread can fail on the first trip of the season, and why tread depth alone stops being a sufficient test after several years.
Is a new tire always new?
No. The date code is the manufacture date, not the sale date, so a tire that has sat in a warehouse for four years is four years old when you fit it. It is worth reading the code before you buy.
What pressure should I run off road?
Roughly 24 to 30 psi on gravel, 14 to 20 on rock, and 12 to 18 in sand — scaled to whatever your vehicle runs on the road. Sand benefits most, because a long footprint floats rather than digs.
How low is too low?
Below about 12 psi a tire can unseat from the rim under side load, which is what beadlock wheels exist to prevent. And always air back up before pavement — low pressure on tarmac builds sidewall heat, and heat destroys tires faster than impacts do.
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