How to identify a real winter tire — in thirty seconds on the sidewall

The Two Symbols

M+S — a specification, not a test

M+S stands for "Mud and Snow." A manufacturer may apply this marking if they deem the tire suitable. There is no testing procedure, no measurement, and no authority that re-checks.

The TCS states it so clearly that it must be quoted: "M+S therefore says nothing about the winter suitability of the tire."[1]

This does not mean that every M+S tire is bad. It means that the marking itself does not prove anything.

The Alpine Symbol — a passed test

The Alpine Symbol is a small mountain with three peaks and a snowflake inside. Officially, it is called 3PMSF, for Three Peak Mountain Snow Flake.

Behind it is a process: According to UNECE Regulation No. 117, the tire must demonstrate a minimum braking performance on snow, measured against a reference tire. If it does not meet the limit, it does not receive the symbol.

The TCS: "Only a tire with the snowflake symbol is a true winter tire."[1]

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How to check it — thirty seconds

1. Go to your car and look at the sidewall of a tire.
2. Look for the mountain. A small triangle with three peaks, containing a snowflake. It is usually near the size designation or on the opposite side.
3. Check all four tires. Mixed sets are more common than one might think — especially with used cars.

If you only find "M+S" or "M&S" without the mountain, you do not have a tested winter tire on board. This may be perfectly sufficient for your driving habits — but it is information you should have before it snows.

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Why this has become more important since 2024

For decades, M+S was sufficient everywhere. This has changed in quick succession:

In Germany, a long transitional period expired: Tires produced before January 2018, bearing only M+S, were tolerated until September 30, 2024.[2] Since then, they are no longer permissible in winter conditions.

Austria, however, continues to accept M+S.[3] This is precisely what makes the situation confusing: the same set of tires is acceptable in one country but not in the neighboring country. Anyone driving across the border in winter should be aware of this — the complete country overview can be found in our article Winter Tire Obligation in Europe.

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The second distinguishing feature: the tread

The symbol is the reliable answer. But you can also see the difference if you know what to look for.

A winter tire has sipes. These are the fine, often zigzag-shaped incisions across the tread blocks — hundreds of them. Each sipe is an additional edge that hooks into the snow. If you hold a winter tire and a summer tire next to each other, the difference is immediately obvious.

A summer tire has wide, closed ribs and few, mostly straight grooves. It needs a large, continuous contact patch because it has to transfer forces on warm asphalt without the blocks collapsing.

An all-season tire is visibly in between — sipes yes, but coarser; plus a continuous center rib like a summer tire. The compromise is visible in the tread.

And the most important part is not even in the tread, but in the rubber compound. A winter compound remains flexible in the cold, a summer compound becomes hard. You can't see this; you only notice it when braking — and see the numbers below for that.

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What the difference means in meters

The TCS measured it. On wet roads at an asphalt temperature of 7 °C, full braking from 80 km/h, test dimension 205/55 R16:[4]

Five and a half meters, at seven degrees and wet — that is, on a perfectly ordinary November day, without a single snowflake.

On snow at minus 3 °C, braking from 50 km/h, it becomes clearer: "A summer tire has no place on snow. With it, the car stops 27 m later — about eight car lengths — than with a winter tire."[5]

These figures are TCS measurements, not ours. We do not operate a test stand. They apply to the stated conditions, the stated dimension, and the best tires in that particular test — not as an average across all models.

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The tread depth: the second number that counts

The symbol indicates what the tire could do when it was new. How much of that capability remains is indicated by the tread depth.

Legally required in Switzerland is 1.6 millimeters across the entire tread — for both summer and winter tires. Art. 58 Para. 4 VTS: "Tires must have tread grooves at least 1.6 mm deep across the entire tread surface."[6] Anyone below this pays 100 francs per deficient tire.[6]

Recommended is significantly more. The TCS: "The TCS continues to recommend replacing winter tires for driving safety reasons when the tread depth falls below 4 mm, and summer tires when the tread depth falls below 3 mm."[7]

Between 1.6 and 4 millimeters lies not a difference of opinion, but the difference between "not punishable" and "still brakes on snow." On a winter tire with 2 millimeters, the sipes are almost gone — the symbol is still on the sidewall, but the function behind it is no longer there.

And important for travel: 1.6 mm is the lowest value in Europe, not the usual. Austria requires 4 mm for winter tires, as do Croatia and the Czech Republic, and Slovenia and Sweden require 3 mm.[3][8] A tire that passes inspection here may have insufficient tread there.

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The three takeaways

1. The mountain with the snowflake is the only symbol backed by a test. M+S is a manufacturer's specification.
2. Check all four tires, not just one. Mixed sets are more common than one might think.
3. Below 4 millimeters, a winter tire is no longer a winter tire, even if the symbol is still on it.

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Further reading: Winter tire obligation in Europe · All-season tires and the law · Understanding tire size · Winter tires in our assortment

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