49 CFR 392.6
No motor carrier shall schedule a run nor permit nor require the operation of any commercial motor vehicle between points in such period of time as would necessitate the commercial motor vehicle being operated at speeds greater than those prescribed by the jurisdictions in or through which the commercial motor vehicle is being operated.
[33 FR 19732, Dec. 25, 1968, as amended at 60 FR 38746, July 28, 1995].