Division 6.4.1 Wind tunnel criteria

F1The wind tunnel design, test methods and the corrections shall provide a value of (C_D × A_f) representative of the on-road (C_D × A_f) value and with a precision of ± 0,015 m².

For all (C_D × A_f) measurements, the wind tunnel criteria listed in paragraph 3.2. of this Sub-Annex shall be met with the following modifications:

1. (a)

   The solid blockage ratio described in paragraph 3.2.4. of this Sub-Annex shall be less than 25 per cent;

2. (b)

   The belt surface contacting any tyre shall exceed the length of that tyre's contact area by at least 20 per cent and shall be at least as wide as that contact patch;

3. (c)

   The standard deviation of total air pressure at the nozzle outlet described in paragraph 3.2.8. of this Sub-Annex shall be less than 1 per cent;

4. (d)

   The restraint system blockage ratio described in paragraph 3.2.10. of this Sub-Annex shall be less than 3 per cent.