Reading the DOT Number: What Tire Age Tells You – and What It Doesn't

The four digits

Look for DOT on the sidewall, followed by several blocks of characters. The last block of four digits is the production date:[1]

• The first two digits: the calendar week
• The last two: the year

Examples:

The complete DOT number consists of several blocks — it also codes for the factory and tire type.[1] Only the last block is relevant to you.

Two surprising facts:

The DOT number is often found only on one side of the tire. If you can't find it, check the inside — you might have to lie down or turn the wheel.

Older tires have three instead of four digits. This is a coding from before 2000, and such a tire should no longer be on a car, regardless of its tread.

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What the number means — and what it doesn't

This is where it gets interesting, because both extremes are wrong.

"A tire lasts six years, then it has to come off"

This is not stated in any Swiss law. There is no legal age limit for car tires. What the law prescribes is the condition: a minimum of 1.6 millimeters of tread across the entire contact surface (Art. 58 Para. 4 VTS), and a roadworthy vehicle (Art. 29 SVG).[2]

"Age doesn't matter as long as there's tread"

Also wrong. Rubber ages, even when unused. UV light, ozone, and heat make the compound harder and more brittle over the years — you can see it in fine cracks in the tread grooves and on the sidewalls.

The ADAC has examined unused new tires and found that their technical properties can deteriorate over the years; it is recommended that new tires should not be older than two years when purchased.[3]

The useful middle ground

The number is not an expiration date, but an indication of when you should take a closer look:

• Up to about 6 years: Age is usually not an issue. The tread matters.
• 6 to 10 years: When changing wheels, inspect the sidewalls and tread grooves. Fine cracks are a sign. For a tire that has been exposed to the elements a lot, they appear sooner.
• Over 10 years: Be honest, regardless of the tread. A tire with 7 millimeters of tread and twelve years of age is not a good tire, but an old tire that has been driven little.

This is a rule of thumb and not a regulation. A tire that lay in a dark cellar for ten years is in better condition than one that stood against a south-facing wall for five years.

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What age really matters for

There are situations where the DOT number is the decisive value:

When buying a used car. Four tires with good tread and DOT 1214 tell you two things: The previous owner last bought tires twelve years ago, and the car has not been driven much. Both are more important than the tread itself.

For caravans and motorhomes. These vehicles stand more than they drive. Here, age is almost always the criterion, not wear — and the tires carry full load in the same spot for months.

For the spare tire. The spare tire has been in the trunk since the car was new. If you need it, you need it urgently.

When buying new. Brand new doesn't mean freshly produced. A tire that has been in storage for two years is new, but not fresh.

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What we guarantee — and what we don't

We deal exclusively in brand new goods — no used, no retreaded tires.

What we do not guarantee is a specific production date. We order from supplier warehouses, and we do not decide which batch a supplier picks. A promise like "maximum six months old" would be impossible for us to keep, so we don't make it.

This is the more inconvenient, but more honest answer. If you need a specific maximum age — for example, for a motorhome — ask before ordering. Then we will clarify it with the supplier before you order, instead of explaining something to you afterwards.

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How to spot an aging tire

The number is one clue, your eye is the other. What to look for:

Fine cracks in the tread grooves. Pull a tread groove apart and look inside. A network of fine lines indicates aging.

Cracks on the sidewall, especially in the area of greatest deformation near the rim.

The feel. A fresh tire feels slightly pliable on the tread, a severely aged one feels hard like plastic. This comparison only works if you have both side by side — at the workshop during a wheel change is the opportunity.

Hardened spots with flat spots, if the tire has been stationary for a long time.

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Three key takeaways

1. The last four digits of the DOT number: week and year. 1024 means 10th week of 2024.
2. There is no legal age limit, but from about six years, a look at the tread grooves and sidewall is appropriate, and over ten years it becomes questionable regardless of the tread.
3. When buying new, the ADAC advice applies: not older than two years. If this is important to you, ask before ordering — not afterwards.

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Further reading: Proper tire storage · Understanding tire size · Frequently asked questions

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