General Knowledge CDL Endorsement Guide

What's tested

• Pre-trip, en-route, and post-trip vehicle inspection procedures
• Basic vehicle control (starting, backing, turning, parking)
• Shifting gears in manual and automated transmissions
• Visual search, communication, and signaling
• Speed management, space management, and following distance
• Night driving, fog, mountain, and adverse weather operation
• Hazard perception and emergency maneuvers
• Driver fatigue, distraction, and impairment
• Accident reporting and basic post-crash duties
• Cargo securement basics and weight definitions (GVWR, GCWR, GAWR)

Study notes

The pre-trip inspection is the single highest-yield topic.

On the General Knowledge written exam and on every state's skills test, the pre-trip inspection generates the most points and the most flunked attempts. Memorize the inspection routine in the order your state's handbook lists it: under-the-hood, in-cab, lights, walk-around, brakes. Knowing the order means you can't skip a part on test day.

Stopping distance is reaction + brake-lag + brake distance.

A loaded tractor-trailer doing 55 mph needs roughly 290 feet to stop on dry pavement, but the FMCSA breaks that into three pieces: about 60 feet of perception, 60 feet of reaction, and 170 feet of brake lag plus actual braking. Test writers love asking which of those parts grow with speed (all of them) and which grow non-linearly (the braking distance, which grows roughly with the square of speed).

Communication is more than turn signals.

You communicate intent with your turn signals, four-way flashers, brake lights, headlights at night, and the horn — but also with your lane position. The FMCSA model manual tells drivers to signal early, signal continuously through the turn, and cancel the signal after — and the test asks about each step.

Manage your space in all six directions.

Ahead, behind, left, right, above (low bridges, electrical wires), and below (loading docks, soft shoulders, rail crossings). The most common written-test question on this topic is the four-second rule for following distance below 40 mph, and one additional second per 10 mph above that.

Fatigue is treated as an impairment.

Federal hours-of-service rules and FMCSA testing material treat sleep deprivation as functionally equivalent to alcohol impairment. Coffee, cold air, music, and rolling the window down are all called out specifically as ineffective long-term fixes. The only fix is to stop and sleep.

How to study for the General Knowledge exam

The single best preparation strategy for any CDL endorsement is to read the relevant chapter of your state's official CDL handbook three times: once to skim, once to highlight, and once to test yourself on the key terms in the chapter sidebars. The questions on the real exam are drawn directly from the handbook, often phrased almost identically to the bolded vocabulary terms. After you've read the chapter, work through every General Knowledge practice test on CDL Prep Hub for the state you live in.

Pace yourself. Most candidates who fail an endorsement exam fail because they tried to cram all eight written tests into a single weekend. Spread your study over two to three weeks, doing 30 minutes a night, and your retention will be dramatically better than a marathon Saturday session. The General Knowledge material in particular rewards spaced repetition because it includes a lot of numbers, regulations, and procedural steps that don't stick after a single pass.

Take the practice test in your state

Every state writes its own version of the General Knowledge exam, but they all conform to the same FMCSA standards. Pick your state below for a 25-question practice test sampled from the CDL Prep Hub question bank.