General Knowledge (Class B) Study Guide
The Class B General Knowledge test pulls from the same FMCSA CDL Manual as Class A, and the question content is largely identical. What changes is the application: Class B applicants are studying to operate single-unit vehicles weighing 26,001 pounds or more — straight trucks, dump trucks, garbage trucks, box trucks, most city buses, and Class B passenger buses. You won't be hauling a trailer over 10,000 pounds (that's a Class A vehicle), so the combination-specific topics aren't on your test.
What Class B drivers actually do
Class B work tends to be local or regional rather than over-the-road. Construction, municipal services, garbage collection, transit, charter buses — these are the typical Class B jobs. The tradeoff is fewer hours away from home in exchange for a smaller pay scale than long-haul Class A. For drivers who don't want to live out of a sleeper berth, Class B is often the better fit.
Test content: nearly identical to Class A
Same five core areas: vehicle inspection, basic vehicle control, safe driving practices, transporting cargo, and emergencies. The rules don't change because your vehicle is shorter — a fully-loaded dump truck still needs adequate following distance, still has a high center of gravity, still requires proper inspection. If anything, Class B vehicles tested in urban environments demand sharper attention to space management since you're working around tighter intersections and more pedestrians.
Inspection still matters
Tread depth requirements are the same: 4/32 on steering tires, 2/32 on others. Brake adjustment, fluid leaks, lights, mirrors, tires, suspension — all of it gets inspected the same way it would on a Class A. The Class B test will ask you about these the same way.
Watch for cargo and weight questions
Class B vehicles like dump trucks and concrete mixers carry shifting loads. Know that wet cement and other liquid-acting cargo behave like a partial liquid load — you'll feel surge during stops and turns. Aggregate (gravel, sand, stone) shifts differently, especially on uneven surfaces. The questions will test whether you understand that high center of gravity plus shifting load equals serious rollover risk in turns.
Backing in tight spaces
Construction sites, alleys, dumpster pads — Class B drivers back into bad situations daily. The general rule on the written test: when in doubt, get out and look (G.O.A.L.). Use a spotter if you have one. Always back to the driver's side when possible because you can see the rear of the vehicle through the side window.
Skipping combination topics
Class A applicants take an additional Combination Vehicles test that covers tractor-trailer-specific content: coupling, uncoupling, fifth wheel inspection, glad hands, and trailer brake operation. As a Class B applicant, you don't take that test. If you later upgrade to Class A, you'll add the Combination test (and Air Brakes if you didn't already have it).
Air Brakes — almost certainly required
Most Class B vehicles have air brakes. If your test vehicle has them, you'll need to pass the Air Brakes section in addition to General Knowledge. If you only pass General Knowledge and not Air Brakes, you'll receive a CDL with an air brake restriction — meaning you can't legally operate a vehicle with air brakes. That's a significant career limitation since the vast majority of Class B jobs use air brake equipment. Take the Air Brakes test along with General Knowledge.
Common Class B endorsement combinations
- Class B + P (Passenger). Charter bus, transit, shuttle. Required for buses carrying 16+ passengers including the driver.
- Class B + P + S (School Bus). School bus drivers. The S endorsement requires P first.
- Class B + N (Tanker). Local fuel delivery, water trucks, milk trucks.
- Class B + H (HAZMAT). Local hazardous waste, fuel oil delivery. HAZMAT also requires a TSA background check.
How to prepare
Take the practice test below. Aim for 90%+ on consecutive attempts before booking your DMV appointment. Pay particular attention to questions you miss — re-read the explanation, then look up the topic in your state CDL Manual. The Manual is free and is the literal source the test is written from.
Don't ignore Air Brakes prep. Most Class B applicants fail to pass on their first DMV visit because they only studied General Knowledge and forgot they needed Air Brakes too. Take both practice tests.
What comes after the written tests
Pass General Knowledge and Air Brakes and you receive your CLP. Hold it 14 days minimum, complete ELDT theory training (FMCSA requirement before the skills test), get behind-the-wheel training at a CDL school, and schedule the skills test. CDLSpot lists CDL schools by location and price.