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 tracks are acceptable as long as the above requirements are met.
4.2 Vehicle The test shall be conducted with a commercial passenger car equipped with an ABS system in mechanical condition according to car manufacturer recommendations. Permitted modifications are as follows: those allowing the number of tyre sizes that can be mounted on the vehicle to be increased; those permitting automatic activation of the braking device to be installed. Any other modification of the braking system is prohibited. Increasing the load on the tyres by adding weight to the vehicle is permitted. Rim adapters or “spacers” for mounting wheels on the vehicle shall not exceed 60 mm.
4.3 Standard reference test tyre For the evaluation of the ice grip performance of passenger car tyres, the reference tyre SRTT P225/60R16 97S as defined in ASTM F2493 shall be used.
4.4 Tyre preparation
4.4.1 General Fit each test tyre on an approved rim in accordance with ISO 4000-1 using conventional mounting methods. The rim width code shall not differ more than 0,5 from the measuring rim. If a commercialized rim is not available for the test vehicle, it will be acceptable to use a rim whose rim width code differs by 1,0 from the measuring rim width code. Ensure proper bead seating with the use of a suitable lubricant. Excessive use of lubricant should be avoided to prevent slipping of the tyre on the wheel rim.BS ISO 19447 pdf download.