On a slippery road, how should your following space compare with the space used under good conditions?
Correct answer: D – Allow much more space
The Minnesota CDL manual’s normal guideline is at least one second for every 10 feet of vehicle length below 40 mph, with another second above 40 mph. That guideline is intended for good conditions. Slippery pavement increases stopping distance, requiring much more space ahead rather than a fixed one- or two-second adjustment.
Source: Minnesota Commercial Driver’s License Manual — § 2.7.1, “Space Ahead”

