There are three classes of Commercial Driver’s Licenses (CDLs): Class A, Class B, and Class C. A Class A CDL allows you to operate combination vehicles with a gross combination weight rating (GCWR) of 26,001 pounds or more, provided the towed vehicle(s) has a gross vehicle weight rating (GVWR) of more than 10,000 pounds. To drive semi-trucks (including flatbeds) or tractor-trailers, this is the class of CDL you should obtain.
To obtain a CDL of any class, you must pass a medical examination, a General Knowledge test on the general theory of commercial driving, and a skills test to show that you can operate commercial motor vehicles of that class safely.
You’ll likely have to pass some other official knowledge tests as well, depending on the class of CDL you’re applying for and the types of vehicles you plan to drive in your career. To drive combination vehicles, you’ll have to pass the Combination Vehicles knowledge test.
The questions on both the General Knowledge test and the Combination Vehicles knowledge test are based on the official Kentucky Commercial Driver License Manual (Kentucky CDL Handbook 2026). However, if you’ve had trouble absorbing the information presented in this study guide, we can help.