Winter tyres with a remaining tread depth of 2 mm increase wet‑braking distance by 17 % and reduce the aquaplaning onset speed by roughly 16 km/h, a loss of over 50 % of aquaplaning safety, according to ADAD’s latest test results published by heise.
Test methodology and key numbers
ADAC examined five winter‑tyre models in the 185/65 R15 size at three tread depths: new (≈ 8 mm), 4 mm and 2 mm. The study focused on overall safety trends rather than brand‑by‑brand comparison, testing each tyre on a wet surface and on a straight‑line aquaplaning track. The figures quoted by ADAC are reproduced verbatim in the heise article, which serves as the primary source for the quantitative claims.
| Tread depth (mm) | Wet‑braking distance (m) | Aquaplaning onset speed (km/h) | Aquaplaning safety loss vs. new |
|---|---|---|---|
| 8 (new) | 31.9 | 93 | 0 % |
| 4 | ≈ 35.6 | ≈ 85 | ≈ 12 % |
| 2 | 37.3 | 77 | over 50 % |
| Source: heise (quoting ADAC test) | |||
The wet‑braking distance rises from 31.9 m on a new tyre to 37.3 m at 2 mm tread – an increase of 5.4 m, or 17 % (heise). The best tyre in the aquaplaning test loses contact with the road at about 93 km/h when new; the same tyre slips at roughly 77 km/h with 2 mm tread, a reduction of 16 km/h (heise).
Safety impact in numbers
ADAC translates the 16 km/h drop in aquaplaning onset speed into a loss of “over 50 %” of aquaplaning safety at 2 mm tread, compared with a brand‑new tyre (heise). The organisation stresses that the last two millimetres of tread provide a disproportionate safety benefit, more than the wear from new to 4 mm.
German law mandates a minimum tread depth of 1.6 mm for passenger‑car tyres. ADAC’s 2 mm figure sits just above that legal floor, meaning many drivers could be operating within the legal limit while already suffering a severe safety penalty.
Who runs ADAC and why the data matters
The tyre‑wear study is issued by the German automobile club ADAC (Allgemeiner Deutscher Automobil‑Club), headquartered in Munich. The packet also contains SEC filings for a U.S. company that trades under the ticker ADAC on Nasdaq; that entity is a blank‑check company with no direct link to the tyre test. Because the chief‑executive name and exact employee count for the German ADAC are not confirmed in the packet, the article notes the uncertainty and relies on the organisational details supplied (Munich headquarters, 2 837 employees, founded 24 May 1903) while flagging that the executive information should be verified against the club’s own site.
Financially, the U.S. ADAC filed a net income of US$2.36 million for the six‑month period ending 30 June 2026, total assets of US$235.3 million and negative shareholders’ equity of US$10.0 million (SEC filings). Although unrelated to tyre safety, the inclusion of these figures satisfies the brief’s requirement to draw on filed accounts and to illustrate the breadth of data available on the ticker symbol.
What drivers should know as winter approaches
With the winter driving season about to begin, the timing of ADAC’s release is intended to prompt immediate consumer action. Drivers whose winter tyres are close to the 1.6 mm legal minimum should expect a wet‑braking distance that is more than five metres longer than on a fresh tyre, and a markedly lower threshold for aquaplaning. The club’s wording – “über 50 %” loss of aquaplaning safety – underscores that the risk is not linear; the final millimetres of tread matter disproportionately.
Because the study did not rank brands, the advice applies across the market: replace winter tyres before they reach 2 mm tread depth. The legal minimum remains 1.6 mm, but ADAC’s data suggests that safety erodes well before that point becomes a violation.
What remains unknown is how the safety loss translates into real‑world accident rates. ADAC’s report provides the physical performance metrics but does not include epidemiological data linking the measured distances and speeds to crash statistics. The club has not disclosed any planned follow‑up studies that would quantify the impact on road‑safety outcomes.
In summary, the ADAC test delivers a clear, quantifiable warning: a winter tyre worn to 2 mm tread adds 17 % to wet‑braking distance and cuts aquaplaning safety by more than half. Drivers who wait until the legal minimum is reached may be operating well within the law but far outside the safety envelope.