A loaded trailer leans noticeably to one side before departure. Why is this a warning?
Correct answer: An off-center load makes rollover more likely
The guide warns against a load that makes the trailer lean. Correct load distribution and investigate the cause before driving.
Source: Washington Commercial Driver Guide, N/10/20; section 6.1.1, physical PDF 89, printed 6-1. ↗
You are driving a tractor without a semitrailer. What does the guide caution about this bobtail configuration?
Correct answer: It can be difficult to stop smoothly, so allow ample space
A bobtail tractor handles and brakes differently from a loaded combination. Do not assume that less total weight guarantees an easy, short stop.
Source: Washington Commercial Driver Guide, N/10/20; section 6.1.3, physical PDF 89, printed 6-1. ↗
A trailer has begun sliding because its wheels locked during braking. Why should you not use the trailer hand valve to straighten it?
Correct answer: More trailer braking can keep the wheels sliding instead of restoring traction
The guide says to release the braking that caused the trailer wheels to lock so they can regain traction. The trailer hand valve is not a device for pulling a skidding trailer straight.
Source: Washington Commercial Driver Guide, N/10/20; section 6.1.5, physical PDF 91, printed 6-3. ↗
Why should a combination driver avoid swinging left before beginning a right turn?
Correct answer: It can invite a vehicle into the space along the rig's right side
An initial left swing can open a tempting gap on the right. Plan enough turning room without inviting another road user into the trailer's swept path.
Source: Washington Commercial Driver Guide, N/10/20; section 6.1.6, physical PDF 91, printed 6-3. ↗
When positioning a tractor-semitrailer for a backing maneuver, which path should you try to arrange first?
Correct answer: A straight backing path
A straight path is preferred. When a curve is unavoidable, backing toward the driver's side improves visibility.
Source: Washington Commercial Driver Guide, N/10/20; section 6.1.7, physical PDF 91, printed 6-3. ↗
During normal driving of an air-braked combination, which control applies the service brakes throughout the combination?
Correct answer: The foot brake
The foot brake sends the braking signal to the tractor and trailer service brakes. Trailer-only hand-valve application is not the normal driving method.
Source: Washington Commercial Driver Guide, N/10/20; section 6.2.1, physical PDF 92, printed 6-4. ↗
On a combination with the usual red, eight-sided trailer air-supply knob, what does pushing it in do?
Correct answer: Supplies air to the trailer system
Pushing in supplies trailer air; pulling out shuts that supply off and commands emergency braking in the described system. Know the controls fitted to your actual vehicle.
Source: Washington Commercial Driver Guide, N/10/20; section 6.2.3, physical PDF 93, printed 6-5. ↗
When a service-line signal asks for trailer braking, where does the relay valve obtain the air it sends to the brake chambers?
Correct answer: From the trailer's air reservoirs
The service line supplies the command; the trailer reservoir supplies the braking air through the relay valve. This arrangement supports quicker application.
Source: Washington Commercial Driver Guide, N/10/20; section 6.2.6, physical PDF 94, printed 6-6. ↗
After coupling, a spring-braked trailer's brakes will not release when air is supplied. Which connection error should be checked?
Correct answer: The service and emergency air lines may be crossed
Crossed lines can send supply air into the service connection instead of charging the trailer tanks needed to release the spring brakes. Verify the connections and the complete brake check.
Source: Washington Commercial Driver Guide, N/10/20; section 6.2.5, physical PDF 94, printed 6-6. ↗
A rig has more than one trailer. During normal operation, which air-line shut-off valves should be closed?
Correct answer: Those at the back of the last trailer
Intermediate valves stay open to supply following units. The valves at the very rear of the final trailer stay closed so air does not escape.
Source: Washington Commercial Driver Guide, N/10/20; section 6.2.7, physical PDF 94, printed 6-6. ↗
Where does the guide place the yellow ABS malfunction lamp on an ABS-equipped trailer?
Correct answer: On the left side, near a front or rear corner
The guide identifies a left-side trailer lamp. Check the correct lamp and the system's specified startup behavior; a lamp is not proof that all equipment is fault-free.
Source: Washington Commercial Driver Guide, N/10/20; section 6.3.1, physical PDF 95, printed 6-7. ↗
Before using coupling instructions on an unfamiliar tractor-trailer, what must you establish?
Correct answer: The correct procedure for that vehicle's coupling equipment
Coupling systems and individual rigs differ. General knowledge supports, but does not replace, training and the manufacturer's equipment-specific procedure.
Source: Washington Commercial Driver Guide, N/10/20; section 6.4, physical PDF 95, printed 6-7. ↗
A semitrailer is set too high before fifth-wheel coupling. What can happen?
Correct answer: The kingpin may fail to couple correctly
For the procedure described, the tractor should slightly raise the trailer as it backs under. Excessive trailer height can produce an unsafe or missed connection.
Source: Washington Commercial Driver Guide, N/10/20; section 6.4.1, step 6, physical PDF 96, printed 6-8. ↗
After coupling, you can see a gap between the trailer apron and the fifth-wheel skid plate. Is the connection ready for travel?
Correct answer: No; the trailer must sit flat with no gap
The supplement requires the apron to lie flat on the skid plate. A gap can signal an incorrect connection and must be resolved before driving.
Source: Washington Commercial Driver Guide Supplement, September 9, 2022; 11M.6.1, Kingpin, Apron & Gap, physical PDF 12, printed 11M-9. ↗
With the trailer's full weight on the tractor, which clearance needs checking?
Correct answer: Space between the tractor frame and landing gear during turns
Check that the tractor frame cannot strike the landing gear and that tire-to-trailer clearance is adequate. The final loaded position matters.
Source: Washington Commercial Driver Guide, N/10/20; section 6.4.1, step 15, physical PDF 97, printed 6-9. ↗
Before uncoupling, you are not sure whether the trailer has spring brakes. What does the guide require for wheel security?
Correct answer: Chock the trailer wheels
If spring brakes are absent or their presence is uncertain, use chocks. Stored air can escape and release an air-dependent holding brake.
Source: Washington Commercial Driver Guide, N/10/20; section 6.4.2, step 3, physical PDF 97, printed 6-9. ↗
During uncoupling, why stop with the tractor frame still under the trailer after the fifth wheel clears?
Correct answer: The frame can keep the trailer from falling far if its support fails
The partial pull-out provides a safety margin if the landing gear sinks or collapses. Secure the tractor and inspect the supports before clearing the trailer completely.
Source: Washington Commercial Driver Guide, N/10/20; section 6.4.2, step 7, physical PDF 97, printed 6-9. ↗
What must be true of an equipped sliding fifth wheel's locking pins before travel?
Correct answer: They are undamaged and fully engaged
The supplement specifically checks the sliding pins for damage and full engagement. The slide must not move unexpectedly under load.
Source: Washington Commercial Driver Guide Supplement, September 9, 2022; 11M.6.1, Locking and Safety Devices, physical PDF 13, printed 11M-10. ↗
For a non-fifth-wheel combination fitted with safety chains, what arrangement does the updated inspection supplement call for?
Correct answer: Secure, crossed chains without kinks or excessive slack
The supplement checks secure, crossed chains or cables with no kinks or excessive slack. Their attachment and capacity must also suit the actual equipment and applicable rules.
Source: Washington Commercial Driver Guide Supplement, September 9, 2022; 11M.6.1, All Other Coupling Systems, physical PDF 13, printed 11M-10. ↗
On a ball-and-coupler trailer covered by Washington's 10,000-pound-or-less towing rule, a safety-chain link is cracked. What is required?
Correct answer: Replace the defective chain immediately
The rule requires immediate replacement of cut, cracked or excessively worn chain links and bars post-manufacture welding repairs. Do not rely on a repaired defective link.
Source: Washington Administrative Code 204-70-070(3), (4)(c); scope 204-70-020/-030; current text reviewed September 13, 2026. ↗
