Question 1 of 20
The trailer hand valve should be used:
Correct. Use the trailer hand valve only for testing trailer brakes. Using it to slow the rig can cause the trailer to skid or jackknife.
Colorado Combination Vehicles CDL Practice Test
This is a free 20-question practice test for the Combination Vehicles portion of the Colorado Commercial Driver's License knowledge exam. Questions are pulled from a pool of 55 drawn from the AAMVA CDL Manual, which is the source document the Colorado Division of Motor Vehicles uses to write its actual exam.
How it works: Click an answer. The correct choice highlights in green, and you'll see a short explanation. Aim for 85% or better before you sit for the real test in Colorado.
Question 2 of 20
Length and weight increase what about a combination vehicle?
Correct. Longer, heavier rigs need more stopping distance, swing wider in turns, have larger blind spots, and require more time and space to change lanes.
Question 3 of 20
A high-mounted trailer kingpin is dangerous because:
Correct. If the trailer is too high, the fifth wheel slides under without the kingpin engaging the locking jaws. The trailer is not coupled and can drop when you pull away.
Question 4 of 20
When you "G.O.A.L." in trucking, you:
Correct. G.O.A.L. — Get Out And Look — is the universal driver-school rule before any tight backing maneuver.
Question 5 of 20
When making a turn, you should signal:
Correct. Signal early enough that other drivers see and process the signal — generally at least 100 feet before in town, longer at highway speeds.
Question 6 of 20
To make a trailer go where you want when backing, the steering wheel should:
Correct. Backing is opposite-direction steering: to swing the trailer right, turn the wheel left first, then correct as the trailer follows.
Question 7 of 20
A jackknife happens when:
Correct. Jackknife is when the drive wheels skid and the trailer continues forward, causing the tractor to pivot — the rig folds at the fifth wheel like a closing knife.
Question 8 of 20
When you are backing a trailer to the right, you should turn the steering wheel:
Correct. When backing, the trailer goes opposite to the way you initially turn the steering wheel. To make the trailer go right (passenger side), start by turning the wheel left.
Question 9 of 20
When you couple, the locking jaws of the fifth wheel must close around:
Correct. The locking jaws must engage the kingpin shank below the head. If the jaws close above the head, the connection is unsafe.
Question 10 of 20
Off-tracking refers to:
Correct. Off-tracking is the tendency for trailer wheels to follow a smaller-radius path than the tractor wheels through a turn, more pronounced with longer wheelbases.
Question 11 of 20
Before backing under a trailer to couple, you should:
Correct. Trailer should be just low enough that the fifth wheel will lift it slightly. Too low: the fifth wheel hits the trailer body. Too high: the fifth wheel slides under without engaging the kingpin.
Question 12 of 20
A safe practice when arriving at a destination is to:
Correct. Slow approach with mirror checks gives time to identify clearance issues and pedestrians.
Question 13 of 20
When you cross railroad tracks in a tractor-trailer, you should:
Correct. Crossing in one gear (without shifting) prevents stalling on the tracks. Never enter a crossing unless you can clear it without stopping.
Question 14 of 20
A loaded trailer "bows" (sways) at speed because:
Correct. Crosswinds and uneven loading can produce trailer sway. Slow down and allow the sway to dampen; do not over-correct with steering.
Question 15 of 20
Cargo securement: the heaviest part of the load should be:
Correct. Loading heavy cargo to the front of the trailer over the drive axles helps with traction; loading to one side or top creates dangerous handling.
Question 16 of 20
To recover from a trailer skid, you should:
Correct. Release the brakes so the trailer wheels can rotate again and re-establish traction. Continued braking will worsen the skid.
Question 17 of 20
When you supply air to the trailer for the first time after coupling, you should:
Correct. Charge the trailer system. Then test the trailer brake function by tugging gently or pulling the trailer-supply knob to confirm trailer brakes apply.
Question 18 of 20
When you connect the glad-hands, you should:
Correct. Push the glad-hands together so the rubber seals match, then rotate to lock. Be sure red goes to red and blue goes to blue (the lines themselves often cross to keep colors matched).
Question 19 of 20
A combination vehicle requires more time to stop than a single vehicle because:
Correct. Greater weight + brake-lag in long air lines = longer stopping distance. Plan ahead.
Question 20 of 20
The most likely cause of a tractor jackknife is:
Correct. When drive wheels lose traction (locked, oversteer, ice), the tractor pivots ahead of the trailer — a jackknife.
About the Colorado Combination Vehicles exam
Most states administer 20 Combination Vehicles questions and require 80% to pass. The exam emphasizes the unique handling of articulated vehicles: how trailers track behind the tractor, how to prevent rollover, how to manage rearward amplification with multi-trailer combinations, and the correct sequence to couple and uncouple.
The Colorado Division of Motor Vehicles follows the federal CDL standards established by FMCSA. To earn the Combination Vehicles credential, you must answer at least 80% of the questions correctly. Many candidates score lower the first time because the test pulls from a large pool — refreshing this page will give you a different mix of questions, drawn from the same authoritative source.
Want more practice? Try the full Combination Vehicles question bank or browse all Colorado CDL practice tests.