View instructions
Safely pulling double and triple trailers requires knowledge and skill. If you want to pull double or triple trailers, you must add the Doubles/Triples (T) endorsement to your Class A CDL. The Colorado doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The CO CDL doubles triples test covers the following sections of the Colorado CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this CO CDL practice test now to prepare for the actual test! Important: Triple trailers are not legal in Colorado.
1. Many large vehicles have convex (curved, "spot, "fisheye") mirrors. Convex mirrors:
are illegal in most states.
make things look smaller and farther away than they really are.
misrepresent reality by showing a larger area than flat mirrors.
None of the above.
2. If a vehicle is equipped with ABS, when you start the engine:
the trailer emergency brakes will come on.
the spring brakes will come on.
the wheels will lock up.
the ABS indicator light on the dash should come on and then turn off.
3. ABS:
helps you avoid skids caused by over braking.
helps you stop faster.
improves your visibility at night.
may cause your wheels to lock when you break hard.
4. Cargo should be properly covered:
to protect people from spilled cargo.
to protect the weather from the cargo.
to block your view or someone else’s.
All of the above.
5. Air storage tanks:
pump air into the air storage tanks.
are installed in the first tank the air compressor pumps air to.
use parts of the service brake systems to stop the vehicle in a brake system failure.
hold compressed air for the brakes.
6. Why should you back toward the driver's side?
You can see better and watch the rear of your vehicle by looking out the side window.
You can more easily correct any steering errors.
Using double clutching requires practice.
All of the above.
7. With an engine fire, you should:
not shoot foam from the vehicle’s underside.
turn the engine off as soon as possible.
open the hood as soon as possible.
All of the above.
8. Which of the following is not proper tie-down equipment:
Bungee cords
9. If you're feeling tired while driving you should:
stop driving and get some rest.
eat something.
drink coffee.
increase your speed to get to your destination quicker.
10. Right after it starts to rain, the road is very slippery. Why?
Because rain is very slippery.
Because black ice may form on the road.
Because the water mixes with oil left on the road by vehicles.
None of the above.
Page 1 of 2
Next page

CO Doubles Triples CDL Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Share This Online CDL Test
Rate this Doubles Triples CDL Test
4.8 out of 5
based on 329 votes