Section 86.135-00 includes text that specifies requirements that differ from §§ 86.135-90 and 86.135-94. Where a paragraph in § 86.135-90 or § 86.135-94 is identical and applicable to § 86.135-00, this may be indicated by specifying the corresponding paragraph and the statement “[Reserved]. For guidance see § 86.135-90.” or “[Reserved]. For guidance see § 86.135-94.”
(d) Practice runs over the prescribed driving schedule may be performed at test point, provided an emission sample is not taken, for the purpose of finding the appropriate throttle action to maintain the proper speed-time relationship, or to permit sampling system adjustment. Both smoothing of speed variations and excessive accelerator pedal perturbations are to be avoided. When using two-roll dynamometers a truer speed-time trace may be obtained by minimizing the rocking of the vehicle in the rolls; the rocking of the vehicle changes the tire rolling radius on each roll. This rocking may be minimized by restraining the vehicle horizontally (or nearly so) by using a cable and winch.