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. By pushing the trailer air supply control knob in, you:
shut the air off and put on the trailer emergency brakes.
supply the tires with air.
supply the trailer with air.
keeps air in the tractor or truck brake system.
2. If there is a fire in your vehicle, do NOT:
park in an open area.
pull into a service station.
park away from buildings and other vehicles.
notify emergency services.
3. If there is a cargo fire in a van or box trailer, you should:
keep driving until you reach help.
open the doors, especially if your cargo contains hazardous materials.
keep the doors shut.
enlist the help of bystanders.
4. You can determine if your vehicle is equipped with ABS (anti-lock braking system) by:
checking if your vehicle was manufactured after March 1, 1998.
checking for a yellow ABS malfunction lamp on the instrument panel.
looking for wheel speed sensor wires coming from the rear of your brakes.
All of the above.
5. If a load is placed on one side of the trailer:
the steering axle weight will be too light to steer safely.
a rollover is more likely.
making turns may be easier.
your brakes won't work.
6. With the controlled braking method:
you lightly tap the brakes.
you apply your brakes all the way and release the brakes when the wheels lock up.
you apply your brakes as hard as possible without locking the wheels.
you use the parking brake to lock the wheels.
7. Empty trucks:
require a greaterĀ stopping distance than full trucks.
require the same stoppingĀ distance than full trucks.
require a shorter stoppingĀ distance than full trucks.
None of the above.
8. If you are being tailgated, you should:
increase your speed very gradually.
turn on your taillights.
make quick changes.
open up room in front of you.
9. Emergency lines are often coded with the color ___ to keep from getting them mixed up with the service line.
10. In a combination vehicle, ________ is most likely to turn over.
the tractor
the last trailer
the trailer behind the tractor
All of the above.
Page 1 of 2
Next page

CO CDL Doubles Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Share This Online CDL Test
Rate this CDL Doubles Test
4.9 out of 5
based on 318 votes