Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:16:p9
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 16 (pt 9/108)
Character Range: 908778–911848

and c2 shall be recalculated with a least squares regression analysis.
              4.5. Correction to reference conditions and measurement equipment
              4.5.1. Air resistance correction factor
              The correction factor for air resistance K2 shall be determined using the following equation:
           where:
                  T is the arithmetic average atmospheric temperature of all individual runs, Kelvin (K);
           P is the arithmetic average atmospheric pressure, kPa.
              4.5.2. Rolling resistance correction factor
              The correction factor K0 for rolling resistance, in Celsius-1 (°C-1), may be determined based on empirical data and approved by the responsible authority for the particular vehicle and tyre combination to be tested, or may be assumed to be as follows:
              4.5.3. Wind correction
              4.5.3.1. Wind correction when using stationary anemometry
              Wind correction may be waived when the arithmetic average wind speed for each valid run pair is 2 m/s or less. In the case that wind speed is measured at more than one part of the test track, such as when the test is performed on an oval test track (see paragraph 4.1.1.1.1. of this annex), the wind speed shall be averaged at each measurement location and the higher of two average wind speeds shall be used to determine whether a wind speed correction is to be applied or may be waived.
              4.5.3.1.1. The wind resistance correction w1 for the coastdown method or w2 for the torque meter method shall be calculated using the following equations:
           or:
           where:
                  w1 is the wind resistance correction for the coastdown method, N;
                  f2 is the coefficient of the aerodynamic term determined according to paragraph 4.3.1.4.4. of this annex;
                  vw in the case that wind speed is measured at only one point, vw is the arithmetic average vector component of the wind speed parallel to the test road during all valid run pairs, m/s;
                  vw in the case that the wind speed is measured at two points, vw is the lower of the two arithmetic average vector components of the wind speed parallel to the test road during all valid run pairs, m/s;
                  w2 is the wind resistance correction for the torque meter method, Nm;
                  c2 is the coefficient of the aerodynamic term for the torque meter method determined according to paragraph 4.4.4. of this annex.
              4.5.3.2. Wind correction when using on-board anemometry
              In the case that the coastdown method is based on on-board anemometry, w1 and w2 in the equations in paragraph 4.5.3.1.1. of this annex shall be set to zero, as the wind correction is already applied according to paragraph 4.3.2. of this annex.
              4.5.4. Test mass correction factor
              The correction factor K1 for the test mass of the test vehicle shall be determined using the following equation:
           where:
           TM  is the test mass of the