BS AU 50-1.1.2 pdf free download

BS AU 50-1.1.2-2001 pdf free download.Passenger car tyres Ð Methods for measuring rolling circumference Ð Loaded new tyres.
5.2 Conditions
5.2.1 Course The test course shall be a level, straight section of smooth, dry road, whose surface is of either asphalt or concrete pavement of medium roughness. The maximum longitudinal and transverse gradient of the road shall be 1 %. The length of the course should preferably be 500 m, but may be longer depending on the accuracy of the test equipment (see 5.4). The length of the test course, expressed in metres, shall be measured to within 0,1 %. There shall be an approach road at both ends of the test course to allow the course to be entered at the test speed. 5.2.2 Weather The ambient temperature shall be between 5 °C and 30 °C. However, any asphaltic surface shall be sufficiently cool so that the surface is not tacky. The wind speed shall not exceed 7 m/s.
5.3 Speed The test speed shall be in the range 80 km/h 2 km/h. For radial tyres, linear assumption is allowed for the relation between rolling circumference values and the speed of the tyre in the range 80 km/h ? 50 km/h.
5.4 Accuracy The minimum number of impulses per revolution shall be 1 6. The overall error in the revolution-counting equipment, including start and stop errors, shall not exceed 0,1 %.
5.5 Vehicle The test vehicle shall be representative of the size of vehicle normally fitted with tyres the same size as those being tested. Because most speedometers and odometers are actuated from the drive-shaft, the test tyres shall be fitted to the drive axle. For four-wheel drive vehicles, one or the other of the drive axles shall be disengaged during the test.
5.6 Test tyre and rim parameters
5.6.1 Tyres The tyres shall be a matched set of the same size, designation, type and brand, having inflated, unloaded overall diameters within 0,5 % of each other. For future comparisons, record the overall diameter of the new tyres, measured according to ISO 4000-1 .
5.6.2 Load The load on the drive axle shall be 80 % of the maximum rated tyre load multiplied by the number of tyres on the axle, to within ? 2 %. The tyres’ maximum load capacity corresponds to the LI moulded on the sidewall of the tyre. If this is not marked, use the maximum permissible tyre load capacity.
5.6.3 Inflation pressure The inflation pressure of the test tyres at ambient temperature shall be 30 kPa less than the reference pressure for the tyre categories specified in annex B of ISO 4000-1 :2000. For tyres not specified in ISO 4000-1 , the reference inflation pressure shall be that given by the tyre manufacturer. 5.6.4 Rims The rims used in the test should be of a size and type approved by the tyre manufacturer for use with the test tyres in highway service. If such rims are not available, or the information is unknown, a standard measuring rim, or the rim nearest to it, shall be used in the test. 5.7 Procedure a) Prior to the test, break in and condition the tyres by running for at least half an hour at an average speed of approximately 80 km/h at the specified load and inflation pressure. b) Immediately after conditioning, run the test at the speed and on the course specified. c) Limit acceleration, braking, and steering to an absolute minimum during the measurements. d) Record the number of revolutions, and parts of revolutions, of the right and left test wheels, during the time taken for the vehicle to complete the test course. e) Repeat the test twice in both directions. If the number of revolutions for each wheel on the second run differs from the first in the same direction by more than 0,2 %, repeat the test until two runs are obtained in each direction within this tolerance. 5.8 Calculation 5.8.1 Calculate for each of the eight readings (i.e. four runs for each drive wheel) according to 4.3.9 e) and average the eight calculations to obtain the rated value. 5.8.2 To determine the rolling circumference, divide the test course length (in metres) by the number of revolutions measured and multiply this by 1 0 3 . Round this value to the nearest unit.BS AU 50-1.1.2 pdf download.