Overview
ISO 19447:2021 specifies a standardized test method for measuring the ice grip performance of new passenger‑car tyres under loaded braking conditions. The method produces a relative ice grip index (GI) by comparing a candidate tyre to a defined reference tyre (SRTT P225/60R16 97S per ASTM F2493). The standard applies to all passenger‑car tyres except T‑type temporary spare tyres and is intended to reduce measurement variability by controlling test course, vehicle, tyre preparation and instrumentation.
Key topics and technical requirements
- Test principle: ABS braking tests on flat, smooth, polished ice; compare mean fully developed deceleration of candidate tyre against the reference tyre to calculate the ice grip index (GI).
- Test cycles: Each candidate tyre is evaluated in three non‑consecutive braking test cycles (initial reference/control, up to two candidate/control tests, final reference/control).
- Test course and environment:
- Flat ice surface with ≤2% gradient; braking line conditioned and stabilized.
- Air temperature: −15 °C to +4 °C (measured ~1 m above ground).
- Ice surface temperature: −15 °C to −5 °C.
- No precipitation; avoid strong sunlight, large humidity or wind variations.
- Reference tyre mean fully developed deceleration must fall between 0.9 m/s² and 1.6 m/s² in each braking test.
- Vehicle: Commercial passenger car equipped with a functioning ABS; limited permitted modifications (e.g., wheel adapters ≤60 mm, added ballast allowed).
- Reference and control tyres:
- Reference tyre per ASTM F2493 (SRTT P225/60R16 97S).
- A control tyre may be used when direct comparison on the same vehicle is not possible; control tyre must meet index thresholds defined by the standard.
- Tyre preparation:
- Correct mounting per ISO 4000‑1; break‑in for studless and studded tyres (≥100 km or equivalent).
- Reconditioning permitted to reach stable performance (e.g., short rough‑road run).
- Stud protrusion measurement: device with 20 mm support plate, 12 mm hole; measurement head pressed perpendicular with 15–20 N; measure 20 consecutive studs and report stud details.
- Tyre load and inflation:
- Reference tyre inflation: 230–260 kPa; control tyre: 190–270 kPa.
- Load‑on‑tyre rate (RLoT) and allowed ranges for direct and indirect comparisons are specified.
Applications and users
- Tyre manufacturers for product development and performance verification (studded and studless winter tyres).
- Automotive OEMs assessing tyre performance for vehicle fitment and safety.
- Independent test labs and certification bodies performing standardized ice braking evaluations.
- Regulators and procurement teams requiring consistent, comparable ice traction data.
Related standards
- ASTM F2493 - defines the standard reference test tyre (SRTT).
- ISO 4000‑1 - passenger car tyres and rims (tyre mounting and sizes).
- ISO 4223‑1 - tyre industry terminology and definitions.
Keywords: ISO 19447, ice grip, passenger car tyres, ice grip index, braking on ice, studded tyres, studless tyres, reference tyre, tyre testing, ABS braking test.