Acerca del examen de General Knowledge (Class A)
The General Knowledge test is the foundation of every Class A CDL exam. About 50 multiple-choice questions covering the core skills any commercial driver needs, regardless of what they're hauling. Most states require 80% to pass.
The most common thing we end up fixing, sometimes before a person even enrolls, is the belief that a Class B will let them drive a semi. It won't, and that one mix-up can cost people months.
A semi is a tractor pulling a separate trailer, and that puts it in Class A. The technical line is a combination rated over 26,001 lbs with a trailer over 10,000 lbs. If you're after over-the-road freight, dry van, reefer, flatbed, the 18-wheeler most people picture when they say truck driver, Class A is the license you need.
Getting a B when you needed an A is not a quick fix later. Most states make you re-test General Knowledge under Class A, add the Combination Vehicles test, and run your skills test in an actual combination vehicle. We would rather catch this on your first day than after you've paid to go the wrong direction.
We tell every class the same thing about studying: the test rewards understanding the rule, not memorizing the answer. The people who pass on the first try can say why an answer is right in their own words. If you find yourself memorizing specific questions, that's usually where it goes sideways. Use the practice test to find what you can't explain yet, then read that section of your state manual.
Qué se cubre
Vehicle Inspection
Pre-trip inspection isn't just for the skills test — it's tested heavily on the written exam. Expect questions on the seven steps of an air brake test, identifying brake system defects, checking slack adjusters, and identifying worn tires. Steering tires must have at least 4/32 inch of tread; all others need 2/32.
Basic Vehicle Control
Backing, turning, and managing space around the vehicle. The most tested concept is off-tracking — the trailer's rear wheels follow a tighter path than the tractor's front wheels in a turn. On a 53-foot trailer, the difference can be 6 to 10 feet.
Safe Driving Practices
Stopping distance, following distance, and hazard awareness. The rule: one second of following distance for every 10 feet of vehicle length under 40 mph, plus one more second above 40. Double your following distance on wet roads.
Transporting Cargo
Weight distribution, securement, and inspection frequency. Cargo must be inspected within the first 50 miles, then every 150 miles or 3 hours of driving, whichever comes first. Overweight or unbalanced loads handle worse and take longer to stop.
Emergencies
Fire, brake failure, blowouts, and skids. Know which fire extinguisher works on which fire type — B:C or A:B:C ratings for most cab fires. For a tire blowout, grip the wheel firmly, stay off the brake, and let the vehicle slow naturally before pulling over.
Consejos para aprobar
- Read every question carefully — many wrong answers sound "safer" than the actual rule. The test measures whether you know the regulation, not your gut feeling.
- Aim for 90%+ on three consecutive practice attempts before booking your DMV appointment.
- If you keep missing the same topic (brakes, cargo, etc.), spend 20 minutes in your state's CDL Manual on that section before retaking.
- The Manual and our practice tests draw from the same FMCSA source material — they reinforce each other.
Errores comunes en el examen de General Knowledge
Estos son los temas que hacen tropezar a la gente una y otra vez — tanto en nuestras aulas como en los intentos de práctica. Léelos con cuidado antes de volver a presentar el examen.
- Confusing stopping distance and following distance. Stopping distance is how far it takes you to physically stop; following distance is the gap to the vehicle in front. The test asks about both, and they're not the same number.
- Getting tread depth backwards. Steering tires require 4/32 inch minimum; all other tires need 2/32. Many applicants reverse the two.
- Forgetting the 50-mile / 150-mile cargo inspection rule. First inspection within the first 50 miles, then every 150 miles or 3 hours, whichever is sooner.
- Picking the "safer-sounding" answer instead of the actual regulation. The test rewards the FMCSA rule, not your gut feeling about what seems careful.
- Treating the General Knowledge test as if it only covers driving. It also covers cargo, vehicle systems, and emergencies in equal measure.
Cómo usar este examen de práctica
Our General Knowledge practice test draws from the same FMCSA source material your state's official CDL manual uses. Take the test as many times as you need — questions reshuffle on every attempt. After each question you'll see whether your answer was correct, the explanation, and a reference to the topic so you can study it deeper.
¿Quieres todo el contexto antes de examinarte? Lee la guía de estudio de General Knowledge con el material completo en el que se basa este examen.