In Partnership with Scott County Library System

View instructions
The CDL general knowledge test is required to be taken by all CDL applicants. The Iowa CDL test consists of 50 questions. To pass, you must correctly answer at least 40 questions (80%). The general knowledge test covers the contents of the Iowa CDL Manual. All CDL applicants (Class A, B and C) must study the following sections: Driving Safely, Transporting Cargo Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Vehicle Inspection Test, Basic Control Skills Test, Road Test. In addition, the Class A CDL test will include questions based on the Combination Vehicles section. Take this CDL practice test now to prepare for the actual IA general knowledge test! To get your CDL, you must pass both the knowledge and skills tests. CDL knowledge tests include: General Knowledge, Passenger Transport, Air Brakes, Combination Vehicles, Hazardous Materials, Tanker Vehicles, Doubles/Triples, School Bus, Firefighter. Depending on what class of license (A, B or C) and endorsements you need, you must take one or more knowledge tests. A special endorsement is also required to drive certain types of vehicles. The following endorsements may be used with a Class A, B or C CDL: HazMat (H), Tank Vehicles (N), Tank Vehicles Transporting Hazardous Materials (X) and Passenger Transport (P). The School Bus endorsement (S) is only available for Class A or B CDL, and the Doubles/Triples endorsement (T) is only available for Class A driver's licenses.
1. When driving on slippery roads, you should NOT:
use the speed retarder.
brake any harder than necessary.
All of the above.
2. A steering wheel play of more than ___ degrees can make it hard to steer.
3. Traction is:
friction between the front and rear tires.
the distance your vehicle will travel while you are braking.
friction between the tires and the road.
4. If you are driving a 30-foot vehicle at 55 mph, you should leave at least _____ between you and the vehicle ahead.
3 seconds
2 seconds
4 seconds
5. The Gross Vehicle Weight Rating (GVWR) is:
the value specified by the manufacturer as the loaded weight of a vehicle, including cargo and trailers.
the value specified by the manufacturer as the loaded weight of a combination vehicle.
the value specified by the manufacturer as the loaded weight of a single vehicle.
6. When inspecting a vehicle's suspension, you should look for broken or missing leaves in the leaf springs.  If ____ or more are missing, it will put the vehicle out of service.
7. On wet roads, you must drive slower to be able to stop in the same distance as on a dry road. Reduce speed by about _______ when driving on a wet road.
70 percent
8. When making a left turn at an intersection, you should:
always take the left turn lane if there are two turning lanes.
always use your horn.
reach the center of the intersection before you start the left turn.
9. ABS helps you:
increase your normal braking capability.
avoid wheel lock up and maintain control of your vehicle when you brake.
steer gently and smoothly while you are braking.
10. When you are driving on a slippery road, you should NOT:
adjust turning and braking to road conditions.
keep a longer following distance.
use the engine brake or speed retarder.
Page 1 of 5
Next page

IA CDL Knowledge Test

Number of questions: 50
Correct answers to pass:40
Passing score:80%
Share This Online CDL Test
Rate this CDL Knowledge Test
4.5 out of 5
based on 257 votes