According to the CDL manual, approximately how far ahead can a driver see at night with low-beam headlights compared to high beams?

49 CFR 383.111(a)(11); AAMVA CDL Manual (nhcdm.pdf) Section 2.11.4, p. 2-26, 'Headlights'

The manual ties these exact visibility distances to a safety rule: you must adjust your speed so you can stop within the distance your headlights let you see, otherwise you'll reach a hazard before you have time to react. Knowing the specific low-beam and high-beam ranges is what lets a driver judge a safe night speed instead of just guessing.