During the truck walk-around, you find tire fabric visible through a cut in the sidewall. The tire still holds air. What should you conclude?
Correct answer: Holding air does not make the tire safe; the damage needs correction before use.
Exposed fabric from a tire cut or other damage is a defect to identify during inspection. Air pressure alone does not establish that a damaged tire is safe.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.1.3 What to Look For - Tire Problems; printed page 2-1, physical PDF page 23. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
After pumping a hydraulic brake pedal, you hold steady pressure and the pedal slowly sinks. What is the appropriate response?
Correct answer: Have the possible hydraulic leak or other brake problem corrected before driving.
The manual describes holding the pedal after pumping it as a hydraulic leak check. A moving pedal during the hold indicates a problem that must be corrected.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.1.5 Seven-step Inspection Method, Step 7 - Test for Hydraulic Leaks; printed page 2-7, physical PDF page 29. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
You must back a tall truck into an unfamiliar loading area. What should the preliminary walk-through include?
Correct answer: Ground-level obstacles, side clearance, and overhead clearance along the entire path.
Before backing, get out and inspect the path. A clear pavement surface does not establish clearance from branches, wires, canopies, or side obstructions.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.2.4 Backing Safely - Look at Your Path; printed page 2-8, physical PDF page 30. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
A helper will watch the blind area while you back toward a dock. What must you agree on before the truck moves?
Correct answer: Clear hand signals, especially the signal that means stop.
A helper supplements the driver’s checks. Agreed signals, particularly a stop signal, prevent confusion during backing.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.2.4 Backing Safely - Use a Helper; printed page 2-8, physical PDF page 30. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
In ordinary conditions, which scanning plan follows the CDL manual’s guidance for anticipating trouble ahead?
Correct answer: Look about 12 to 15 seconds ahead while also checking nearer traffic and the mirrors.
The manual recommends a 12-to-15-second look-ahead range. It is a scanning guide, not a reason to ignore nearby hazards or mirrors.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.4.1 Seeing Ahead; printed page 2-10, physical PDF page 32. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
A car looks small and far away in your truck’s curved mirror. How should this affect a lane-change decision?
Correct answer: Allow for the mirror making objects appear smaller and farther away than they are.
Convex mirrors expand the field of view but distort apparent size and distance. Use the complete mirror-check routine and a genuinely safe gap.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.4.2 Seeing to the Sides and Rear - How to Use Mirrors; printed page 2-11, physical PDF page 33. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
A loaded truck approaches a curve with a posted advisory speed commonly used by cars. What is the safest plan?
Correct answer: Reduce speed before entering; the posted curve speed may still be too fast for the truck.
A truck’s load and center of gravity affect its safe curve speed. Slow before the curve instead of relying on a speed suitable for a passenger car.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.6.3 Speed and Curves; printed page 2-15, physical PDF page 37. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
Under good conditions, a 40-foot commercial vehicle is traveling at 55 mph. What following interval matches the manual’s length-and-speed guideline?
Correct answer: At least five seconds.
The manual recommends one second per 10 feet of vehicle length below 40 mph, plus one additional second above 40 mph. Forty feet at 55 mph gives five seconds; adverse conditions require more.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.7.1 Space Ahead; printed page 2-16, physical PDF page 38. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
You are approaching an icy stretch with the retarder switched on. What does the CDL manual recommend?
Correct answer: Turn the retarder off when traction is poor.
Retarders act through the drive wheels and can cause a skid on slippery surfaces. The manual advises turning them off in poor-traction conditions.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.3.4 Retarders; printed pages 2-9, 2-10, physical PDF pages 31, 32. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
After a long drive on a hot day, a properly inflated tire shows a higher pressure than its cold reading. Should you bleed air to restore the cold reading?
Correct answer: No; normal heating raises pressure, and bleeding air can leave the tire underinflated when it cools.
Do not let air out of hot tires simply because their pressure has risen. If a tire is excessively hot, stop safely and let it cool while addressing the cause.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.14.1 Vehicle Checks - Tires; printed page 2-29, physical PDF page 51. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
Your loaded truck is about to descend a long, steep grade. When should you select the suitable low gear?
Correct answer: Before starting down the grade, while speed is under control.
Plan the safe speed and gear before descending. Engine braking should carry much of the speed-control load; late downshifting can fail when engine speed is too high.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.16.2 Select the Right Gear Before Starting Down the Grade; printed page 2-32, physical PDF page 54. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
On a slippery curve, the truck keeps sliding straight despite your steering input. What is the useful response?
Correct answer: Reduce the demand on the front tires and slow down so they can regain traction.
A front-wheel skid means the front tires lack traction to steer. More steering does not restore that traction; reduce the cause of the skid and slow the vehicle.
Source: Iowa DOT official older National CDL Manual, Hy-Brid Version October 2023, July 2017 technical core; 2.19.3 Front-wheel Skids; printed page 2-37, physical PDF page 59. Older technical guide only: current media326 edition equivalence and current Iowa licensing requirements are not established by this source. ↗
