During a truck walk-around, rusty streaks lead away from several wheel nuts. What do they suggest?
Correct answer: The nuts may be loose and need their tightness checked
Rust around wheel nuts can signal movement from looseness. Check the wheel fastening condition rather than treating the streaks as merely cosmetic.
Source: Washington Commercial Driver Guide, N/10/20; section 2.1.3, physical PDF 30, printed 2-2. ↗
For a truck subject to 49 CFR 393.75, which pair gives the minimum major-groove tread depths for front tires and other tires?
Correct answer: 4/32 inch at the front; 2/32 inch on the other tires
Measure major grooves, excluding tie bars, humps and fillets. These are minimum depths, not a guarantee that a tire with other damage is safe.
Source: 49 CFR 393.75(b)-(c); tread depth and measurement exclusions. ↗
Two safe approaches to a loading area are available. Why is backing toward the driver's side generally preferred?
Correct answer: It provides a better view of the vehicle's rear path
Driver-side backing improves visibility, including the view through the side window. Both mirrors and checks of the whole path still matter.
Source: Washington Commercial Driver Guide, N/10/20; section 2.2.4, physical PDF 36, printed 2-8. ↗
You are approaching a long downgrade in a loaded truck. When should you select the appropriate low gear?
Correct answer: Before starting down, while speed is still controlled
Slow and select the right gear before the descent. Waiting until speed builds can make a downshift impossible and remove engine braking when it is most needed.
Source: Washington Commercial Driver Guide, N/10/20; section 2.3.1, physical PDF 37, printed 2-9. ↗
A vehicle looks small and distant in your truck's convex mirror. What should you remember before moving sideways?
Correct answer: It may be closer than the mirror image makes it appear
Convex mirrors show a wider area but make objects look smaller and farther away. Account for this distortion when judging nearby traffic.
Source: Washington Commercial Driver Guide, N/10/20; section 2.4.2, physical PDF 39, printed 2-11. ↗
Your interstate CMV breaks down on a rural highway shoulder where warning devices are required. When should you place them?
Correct answer: As soon as possible, and within 10 minutes
Activate hazard flashers immediately. Place the required warning devices promptly; ten minutes is the outside limit, not a waiting period.
Source: 49 CFR 392.22(a), (b)(1); breakdown outside municipal exceptions. ↗
Your tall loaded truck approaches a signed curve. Does the posted curve speed guarantee that your truck will not roll over?
Correct answer: No; its load and high center of gravity may require a lower speed
A top-heavy truck can roll even when its tires retain grip. Select a safe speed before entering, taking the vehicle and load into account.
Source: Washington Commercial Driver Guide, N/10/20; section 2.6.3, physical PDF 43, printed 2-15. ↗
What happens when a truck hydroplanes in standing water?
Correct answer: A water layer reduces the tires' contact with the road
Hydroplaning reduces tire contact and traction, limiting both steering and braking control. Slow beforehand and avoid standing water where possible.
Source: Washington Commercial Driver Guide, N/10/20; section 2.6.2, physical PDF 42, printed 2-14. ↗
A van trailer cleared a low structure while loaded. After unloading, is that earlier clearance enough proof for the return trip?
Correct answer: No; the unloaded vehicle can sit higher, so clearance must be checked
Suspension height can increase after unloading. Know the current vehicle height and actual available clearance instead of relying on the earlier passage.
Source: Washington Commercial Driver Guide, N/10/20; section 2.7.4, physical PDF 45, printed 2-17. ↗
A cardboard box lies in your truck's lane. What is the prudent assumption while planning a safe response?
Correct answer: It may contain something heavy enough to damage the vehicle
The contents are unknown. Spot debris early so you can avoid it without an abrupt, unsafe maneuver.
Source: Washington Commercial Driver Guide, N/10/20; section 2.8.2, physical PDF 47, printed 2-19. ↗
You have heavy eyelids and cannot remember the last few miles of your truck route. What should you do?
Correct answer: Stop at a safe place and get sleep before continuing
These are warning signs of fatigue. Noise, cool air or stimulants do not replace sleep or reliably make continued driving safe.
Source: Washington Commercial Driver Guide, N/10/20; section 2.11.2, physical PDF 53, printed 2-25. ↗
After highway driving in hot weather, tire pressure is higher than its correct cold setting. What should you avoid?
Correct answer: Bleeding air merely to restore the cold-pressure reading
Heat raises inflation pressure. Releasing air to the cold setting while the tire is hot can leave it underinflated once it cools.
Source: Washington Commercial Driver Guide, N/10/20; section 2.14.1, physical PDF 57, printed 2-29. ↗
You have a clear path across the railroad tracks in a manual-transmission truck. How should you handle the gear selection?
Correct answer: Choose a suitable gear beforehand and avoid shifting on the tracks
Avoid a missed shift or loss of drive while occupying the crossing. Be sure the whole vehicle can clear before entering.
Source: Washington Commercial Driver Guide, N/10/20; section 2.15.5, physical PDF 59, printed 2-31. ↗
A front tire suddenly blows out and no collision is immediately unavoidable. What is the guide's first control advice?
Correct answer: Grip the wheel firmly and avoid braking until speed drops
Maintain directional control and avoid the hard braking that can worsen a blowout. Once slowed, brake gently, pull off safely and check the tires.
Source: Washington Commercial Driver Guide, N/10/20; section 2.17.4, physical PDF 63, printed 2-35. ↗
The ABS malfunction lamp comes on while driving, but there is no indication that the regular brakes have failed. What does that lamp mean?
Correct answer: ABS assistance may be lost; regular braking remains, and the fault needs service
An ABS fault does not by itself mean loss of the normal brake system. Maintain safe braking and arrange service; respond separately to any actual brake fault.
Source: Washington Commercial Driver Guide, N/10/20; section 2.18.7, physical PDF 64, printed 2-36. ↗
A firmly tied load blocks your access to the truck's emergency equipment. Is its arrangement acceptable?
Correct answer: No; secure cargo must also leave ready access to emergency equipment
A load can be firmly secured and still be unsafe because it obstructs emergency access, controls or vision. Correct the arrangement before driving.
Source: 49 CFR 392.9(a)(3); emergency access and cab obstructions. ↗
Your trailer is sealed and you have been ordered not to open it for inspection. What remains important despite that inspection exception?
Correct answer: Check gross and axle weights and the vehicle's external condition
The sealed-load exception does not certify safe weights or the condition of the vehicle. Respect the seal and verify the checks that remain possible, including gross and axle loads.
Source: Washington Commercial Driver Guide, N/10/20; section 3.3.5, physical PDF 74, printed 3-3. ↗
Your truck has too little weight on its drive axles for the conditions. Which difficulty is more likely?
Correct answer: Drive-wheel spin and reduced traction
Drive tires need adequate traction to move the load. Too little drive-axle weight can make wheelspin especially troublesome in bad weather.
Source: Washington Commercial Driver Guide, N/10/20; section 3.2.4, physical PDF 73, printed 3-2. ↗
An 8-foot article weighs only 500 pounds and is not blocked against forward movement. Under the general rule, what is the minimum tiedown count?
Correct answer: Two tiedowns
An unblocked article longer than five feet and no longer than ten feet needs at least two, regardless of its low weight. This assumes no commodity-specific rule and sufficient securement strength.
Source: 49 CFR 393.110(b)(2)(ii); over 5 through 10 feet, unblocked. ↗
Why must a truck's front-end header board be sound and properly secured?
Correct answer: It helps resist cargo moving forward during a sudden stop
A header board protects the front of the cargo area against forward load movement. A damaged structure may not provide that restraint.
Source: Washington Commercial Driver Guide, N/10/20; section 3.3.3, physical PDF 74, printed 3-3. ↗
