Overview
ISO 18106:2016 specifies reproducible methods for measuring the snow grip performance of loaded, new tyres intended for passenger cars, commercial vehicles, trucks and buses. The standard defines how to compare a candidate tyre’s performance to a Standard Reference Test Tyre (SRTT) and expresses results as a Snow Grip Index (SG). The methods (braking on snow for passenger cars and commercial/commercial light vehicles; acceleration on snow for truck and bus tyres) are designed to reduce measurement variability and support consistent winter tyre testing on packed snow surfaces.
Keywords: ISO 18106, snow grip performance, Snow Grip Index, tyre testing, braking on snow, acceleration on snow, packed snow surface.
Key technical topics and requirements
- Scope and objective
- Measures relative snow grip (candidate tyre vs. reference tyre) under loaded conditions for new tyres.
- Applies to passenger car, commercial vehicle, truck and bus tyres.
- Test types
- Braking on snow: primary method for passenger car and commercial vehicle tyre braking performance (mfdd - mean fully developed deceleration).
- Acceleration on snow: method used for truck and bus tyres (AFC - acceleration force coefficient; AA - average acceleration).
- Test surface and environmental conditions
- Flat test course (max 2% gradient) with packed snow: hard base ≥3 mm? (document specifies hard packed base at least 3 cm and a prepared surface layer about 2 cm).
- Air temperature about 1 m above ground: −2 °C to −15 °C; snow temperature: −4 °C to −15 °C.
- Snow compaction index (ASTM F1805 CTI penetrometer): between 75 and 85.
- Tyre preparation and mounting
- Mount per relevant rim standards, remove moulding flash, condition tyres at ambient outdoor temperature for at least two hours prior to testing.
- Loads, pressures and instrumentation
- Tyre loads: 60%–90% of tyre load-index.
- Example cold inflation pressure for passenger car tests: 240 kPa.
- Use calibrated sensors suitable for winter testing; procedures include defined testing order, sequences, data evaluation and reporting.
- Reference and control tyres
- Use specified SRTTs (ASTM E1136, F2870, F2871, F2872) to limit variability.
- A control tyre can be used when candidate and reference tyres cannot be tested on the same vehicle.
Practical applications and who uses this standard
- Tyre manufacturers and R&D teams for winter tyre development and benchmarking.
- Independent test laboratories and certification bodies performing standardized snow grip tests.
- Vehicle OEMs and fleet operators assessing tyre performance for safety and procurement.
- Regulators and standards committees comparing winter tyre safety claims.
- Automotive safety engineers and performance analysts comparing braking and traction metrics.
Related standards
- ISO 4000-1 (passenger car tyres and rims)
- ISO 4209-1 (truck & bus tyres and rims)
- ASTM F1805 (snow compaction CTI penetrometer)
- ASTM E1136, F2870, F2871, F2872 (Standard Reference Test Tyres)
Use ISO 18106:2016 to ensure consistent, comparable measurements of snow grip performance across tyre types and testing organizations.