Foreword

4Test methods

4.1Braking on snow method for passenger car tyres

4.1.1General

4.1.2Test course

4.1.3Vehicle

4.1.4Standard reference test tyre

4.1.5Tyres preparation

4.1.6Tyre load

4.1.7Tyre inflation pressure

4.1.8Instrumentation

4.1.9Testing order and sequences

4.1.10Test procedure

4.1.11Data evaluation and presentation of results

4.1.11.1Coefficient of variation

4.1.11.2SRTT weighted variance

4.1.11.3Snow Grip Index

4.1.11.4Statistical validation

4.1.12Snow grip performance comparison between a candidate tyre and a reference tyre using a control tyre

4.1.12.1General

4.1.12.2Snow Grip Index calculation in case of a control tyre

4.1.12.3Boundary conditions

4.2Braking on snow method for commercial vehicle tyres

4.2.1General

4.2.2Test course

4.2.3Vehicle

4.2.4Standard reference test tyre

4.2.5Tyres preparation

4.2.6Tyre load

4.2.7Tyre inflation pressure

4.2.8Instrumentation

4.2.9Testing order and sequences

4.2.10Test procedure

4.2.11Data evaluation and presentation of results

4.2.11.1Coefficient of variation

4.2.11.2SRTT weighted variance

4.2.11.3Snow Grip Index

4.2.11.4Statistical validation

4.2.12Snow grip performance comparison between a candidate tyre and a reference tyre using a control tyre

4.2.12.1Snow Grip Index calculation in case of a control tyre

4.2.12.2Boundary conditions

4.3Acceleration on snow method for truck and bus tyres

4.3.1General

4.3.2Test course

4.3.3Vehicle

4.3.3.1General

4.3.3.2Vehicle particular case

4.3.4Standard reference test tyre

4.3.5Tyres preparation

4.3.6Tyre load

4.3.7Tyre inflation pressure

4.3.8Instrumentation

4.3.9Testing order and sequences

4.3.10Test procedure

4.3.10.1General

4.3.10.2Vehicle without Traction Control System

4.3.11Data evaluation and presentation of results

4.3.11.1Coefficient of variation

4.3.11.2SRTT stability coefficient

4.3.11.3Calculation of the “average AA”

4.3.11.4Acceleration force coefficient (AFC) calculation

4.3.11.5Snow Grip Index

4.3.11.6Calculation of the Slip Ratio

4.3.12Snow grip performance comparison between a candidate tyre and a reference tyre using a control tyre

4.3.12.1Snow Grip Index calculation in case of a control tyre

4.3.12.2Boundary conditions