Overview
- The ADAC released its results on Tuesday after machine‑abrading five 185/65 R15 winter‑tyre models and testing them at about 8 mm, 4 mm and 2 mm to isolate the effect of tread wear.
- The tests show performance falls disproportionately below 4 mm, with longitudinal aquaplaning reserves down about 12% at 4 mm and 22% at 2 mm and lateral aquaplaning losses roughly 25% at 4 mm and more than 50% at 2 mm.
- Worn tyres also lengthened wet stopping distances, with average braking rising from 31.9 metres for new tyres to 37.3 metres at 2 mm, an increase of about 5.3 metres or 17%.
- Based on those findings the ADAC formally recommends replacing winter tyres at 4 mm even though German law allows use down to 1.6 mm, and it also warns drivers to watch tyre age and visible damage.
- Manufacturers differ in response: some, including Continental, say the legal limit is too low, while Michelin rejects a blanket 4 mm rule and says its tyres are designed to perform to the 1.6 mm minimum; consumers can check tread with a depth gauge, the one‑euro coin trick or the DOT code for age.