A truck's drive wheels begin spinning as the driver accelerates on a wet surface. What is the appropriate immediate adjustment?
Correct answer: Ease off the accelerator to reduce the spinning.
Too much driving power for the available traction can make the wheels spin and threaten control. Reduce acceleration and build speed gradually when grip is poor.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.1, accelerating and rollback; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
Why should a driver pulling a trailer avoid a jerky start?
Correct answer: It can place damaging loads on the coupling and drivetrain.
A smooth, gradual start protects the coupling and other mechanical components and helps maintain control. A harsh surge is not a useful way to test a connection.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.1, accelerating and rollback; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
A manually shifted truck is stopped uphill. When should the driver release a parking brake being used to prevent rollback?
Correct answer: When enough engine power is applied to prevent rolling backward.
Coordinate the clutch, power and brakes so the vehicle does not roll backward into someone behind it. When using the parking brake for this purpose, release it after sufficient power is available.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.1, accelerating and rollback; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
On an uneven road, what steering-wheel grip gives a truck driver better control if a pothole jars the wheel?
Correct answer: A firm grip with hands on opposite sides of the wheel.
Holding the wheel firmly with both hands on opposite sides helps resist an unexpected pull from a pothole or curb. This is a control habit, not a guarantee against loss of control.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.2, steering; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
Two suitable parking spaces are available. Which arrangement reduces a large vehicle's reversing risk?
Correct answer: The one that allows a forward departure when leaving.
Avoid reversing when a safe forward departure is practical. Backing exposes areas the driver cannot fully see, so parking position can remove an unnecessary maneuver.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.4, backing safely; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
Before backing a truck into an unfamiliar yard, what should the driver inspect outside the cab?
Correct answer: The full path, including side space and overhead obstructions.
Walk and inspect the intended path before backing. Check the sides, overhead space and surrounding hazards, not just the patch of ground immediately behind the wheels.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.4, backing safely; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
Why does the handbook recommend the lowest reverse gear and very slow backing?
Correct answer: They leave more time to correct steering and stop.
Low reversing speed helps the driver correct small steering errors and stop promptly. It does not remove blind spots or replace an outside check.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.4, backing safely; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
When either approach is safely available, why favor a backing turn toward the driver's side?
Correct answer: The driver can see the rear path better from that side.
Driver-side backing improves visibility of the rear path, including through the side window. Continue checking both sides and stop to investigate uncertainty; improved visibility does not eliminate risk.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.4, backing safely; printed 2-8; PDF page 40. Reviewed September 21, 2026. ↗
Before a helper guides a truck's reversing maneuver, what should both people agree on?
Correct answer: Clear hand signals, especially the signal to stop.
The driver and helper need a shared set of understandable signals, with a definite stop signal. Position the helper where the driver can see them and do not keep moving if communication or clearance becomes uncertain.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.2.4, helper signals; printed 2-9; PDF page 41. Reviewed September 21, 2026. ↗
Which truck transmission commonly requires double-clutching to change gears?
Correct answer: An unsynchronized manual transmission.
Most heavy-vehicle unsynchronized manual transmissions use double-clutching. A synchronized manual does not require that technique merely because it is a manual. Learn the system fitted to the actual vehicle.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.3.1, manual shifting and downshifting; printed 2-9; PDF page 41. Reviewed September 21, 2026. ↗
A driver changes to a truck with a different engine and gearbox. How should the driver establish suitable shift points?
Correct answer: Learn that vehicle's operating ranges and use its gauges.
Shift points depend on the vehicle. Use the manufacturer's operating information and the tachometer or known road-speed ranges; some systems use progressive shifting rather than one fixed RPM for every gear.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.3.1, manual shifting and downshifting; printed 2-9; PDF page 41. Reviewed September 21, 2026. ↗
A truck is approaching a long descent. When should the driver slow and select an appropriate lower gear?
Correct answer: Before beginning the descent.
Choose the safe speed and suitable gear before starting down. Appropriate engine braking helps control the descent and avoids depending on heavy service-brake use that can overheat the brakes.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.3.1, manual shifting and downshifting; printed 2-9; PDF page 41. Reviewed September 21, 2026. ↗
Before a planned curve in a manually shifted truck, what preparation best supports control?
Correct answer: Reduce speed and select the appropriate gear before entering.
Complete the planned speed reduction and gear selection before the curve. This leaves the driver better able to steer smoothly without an avoidable shift or abrupt braking demand during the turn.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.3.1, manual shifting and downshifting; printed 2-9; PDF page 41. Reviewed September 21, 2026. ↗
A truck has a retarder acting through the drive wheels. What does the handbook advise when those wheels have poor grip on ice?
Correct answer: Turn the retarder off to avoid provoking a drive-wheel skid.
A retarder can demand more grip than slippery drive tires have available. The handbook advises turning it off on wet, icy or snow-covered roads; understand the vehicle's instructions and use a suitably low speed.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.3.4, retarders and traction; printed 2-10; PDF page 42. Reviewed September 21, 2026. ↗
Which scanning pattern matches the handbook's guidance for a commercial driver?
Correct answer: Look at least 12 to 15 seconds ahead while also checking nearer hazards.
The 12-to-15-second look-ahead guidance gives time to plan. It is not a following-gap rule or a reason to stare at one point: shift attention between near, far and surrounding traffic.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.4.1, looking ahead; printed 2-10; PDF page 42. Reviewed September 21, 2026. ↗
Before a tractor-trailer trip, in what alignment should the driver check the mirror adjustment?
Correct answer: With the combination straight, showing a small vehicle reference.
Check adjustment with the trailer straight. Showing part of the vehicle gives a reference for judging other images. Proper adjustment still leaves blind areas that need careful monitoring.
Source: SCDMV CDL Manual, March 2025 body version; Section 2.4.2, mirror adjustment; printed 2-10; PDF page 42. Reviewed September 21, 2026. ↗
