BS ISO 19447:2021 pdf download – Passenger car tyres — Method for measuring ice grip performance — Loaded new tyres 4.1 Braking on ice method for passenger car tyres 4.1.1 General The ice performance is determined by a test method in which the mean fully developed deceleration of a candidate tyre in an ABS braking test on a flat surface made of ice is compared with that of a reference tyre. For determination of the ice performance, braking tests of a candidate tyre shall be performed in three non-consecutive braking test cycles. The relative performance shall be indicated by an ice grip index (G I ). 4.1.2 Test course The braking tests shall be done on a flat test surface of sufficient length and width covered with smooth ice with a maximum of 2 % gradient. The test course surface shall be flat, smooth, polished ice and watered at least 1 h before testing. The water used to make the ice shall be clean and free of any solid inclusions. Before starting the test the braking line should be conditioned by conducting a braking test with tyres not involved in the test programme until the friction level stabilizes. When testing studless tyres, the exact same test line shall be used for all braking test repetitions. When testing studded tyres, the braking lines shall not overlap. The reference tyre shall be tested on its own braking line and the studded tyres next to it on their own individual braking lines. The line for the reference tyre shall be kept clean from ice and snow dust. The studded tyres shall be driven on new clean braking lines. The surface grip level shall be controlled by measurements with the reference tyre. The average mean fully developed deceleration of the reference tyre shall be not less than 0,9 m/s 2 and not greater than 1,6 m/s 2 in each braking test. The air temperature, measured about 1 m above the ground, shall be between −15 °C and +4 °C; the ice temperature, measured on the surface of the conditioned line, shall be between −15 °C and −5 °C. Both air and ice temperatures shall be reported for each tested tyre. Tests cannot be conducted during snowfall or rainfall or any atmospheric precipitation. It is recommended that direct sunlight, large variations of sunlight or humidity, and wind are avoided. Indoor and outdoor facilities for ice...

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