This first set concentrates on high-value safety concepts found in the general knowledge sections of state CDL manuals.
01Pre-trip awareness
02Space management
03Stopping distance
04Cargo checks
05Hazard recognition
06Emergency response
PRACTICE MODE
General Knowledge Test 1
Questions appear in a new order on each attempt. Choose one answer, review the explanation, and use Back or Next to move through the test.
Question 1 of 25Score 0
What minimum tread depth is generally required in every major groove of a front steering tire?
Answer: 4/32 inch Steering-axle tires generally need at least 4/32 inch of tread in every major groove. Other tires generally require at least 2/32 inch. Study: General Knowledge — vehicle inspection
What is the general minimum tread depth for tires other than front steering tires?
Answer: 2/32 inch Most non-steering tires must have at least 2/32 inch of tread in every major groove. A current state manual remains the final authority for inspection rules. Study: General Knowledge — tires
After beginning a trip, when should cargo and securement devices first be rechecked?
Answer: Within the first 50 miles CDL manuals direct drivers to inspect cargo and securement within the first 50 miles. This early check can reveal shifting or loosening that occurred after departure. Study: General Knowledge — cargo inspection
After the first cargo recheck, what is the standard interval for another inspection while driving?
Answer: After 3 hours or 150 miles, whichever comes first Cargo should generally be rechecked after three hours or 150 miles, whichever comes first, and after every break taken while driving. This helps catch movement or loosened securement. Study: General Knowledge — cargo inspection
Below 40 mph, what following-distance guideline applies to a commercial vehicle?
Answer: At least 1 second for each 10 feet of vehicle length The standard guideline is at least one second for each 10 feet of vehicle length at speeds below 40 mph. Add another second when traveling faster than 40 mph. Study: General Knowledge — space management
Why can an empty truck require more stopping distance than a loaded truck?
Answer: It may have less traction Some empty trucks have less traction because there is less weight on the tires. A lightly loaded vehicle can therefore take longer to stop than many drivers expect. Study: General Knowledge — stopping distance
What is the safest general rule about backing a commercial vehicle?
Answer: Avoid backing whenever possible Backing creates large blind areas and should be avoided when a safer setup is available. When backing is necessary, use a helper when possible and get out to look. Study: General Knowledge — backing safely
What does “get out and look” help a driver do before or during backing?
Answer: Verify the path and clearances directly Getting out and looking lets the driver see hazards that mirrors may not reveal. Repeat the check whenever position or clearance becomes uncertain. Study: General Knowledge — backing safely
When should most speed reduction for a curve occur?
Answer: Before entering the curve Slow to a safe speed before entering a curve, then use smooth control inputs. Hard braking in a curve can increase skid or rollover risk. Study: General Knowledge — curves
When should a driver select a safe low gear for a long, steep downgrade?
Answer: Before starting down the grade Choose a safe gear before descending. Proper gear selection lets engine braking help control speed and reduces service-brake heating. Study: General Knowledge — downgrades
What is brake fade?
Answer: Loss of braking effectiveness caused by excessive heat Repeated or prolonged braking can generate enough heat to reduce friction and braking power. Using a safe gear and proper downgrade technique helps prevent fade. Study: General Knowledge — brake fade
If brakes fail on a downgrade and an escape ramp is available, what should the driver do?
Answer: Use the escape ramp Escape ramps are designed to stop runaway vehicles and can save lives. Use one when needed even if the vehicle may be damaged. Study: General Knowledge — mountain driving
What is the first safe response to a tire blowout while moving?
Answer: Hold the steering wheel firmly and stay off the brake initially A firm grip helps maintain direction while the vehicle slows. Braking hard immediately can worsen loss of control; slow gradually and move off when stable. Study: General Knowledge — tire failure
What is a correct statement about antilock brakes?
Answer: They help prevent wheel lock and preserve steering control ABS helps keep wheels from locking during hard braking so the driver may retain control. It does not guarantee a shorter stop or remove the need for safe speed and following distance. Study: General Knowledge — ABS
What should a driver do when hydroplaning begins?
Answer: Ease off the accelerator and avoid sudden braking or steering Hydroplaning reduces tire contact with the road. Smoothly reducing speed and avoiding abrupt inputs helps the tires regain traction. Study: General Knowledge — wet roads
Why should a driver be especially cautious on bridges in cold weather?
Answer: Bridge surfaces may freeze before the road Air circulates above and below a bridge, allowing its surface to cool quickly. A bridge can be icy even when the approaching road is only wet. Study: General Knowledge — winter driving
How far ahead should a commercial driver generally look while driving?
Answer: About 12 to 15 seconds Looking 12 to 15 seconds ahead provides time to identify changing traffic, signals, and road hazards. Looking farther ahead supports smoother, earlier decisions. Study: General Knowledge — seeing hazards
When should a driver dim high beams for an approaching vehicle?
Answer: Before the lights create glare for the other driver High-beam glare can temporarily reduce another driver’s vision. Dim them early enough to protect both drivers’ ability to see. Study: General Knowledge — night driving
How soon should emergency warning devices generally be placed after a commercial vehicle stops on the road?
Answer: Within 10 minutes Federal-style CDL guidance calls for warning devices to be placed within 10 minutes. Turn on four-way flashers immediately and use the correct placement for the road type. Study: General Knowledge — emergency warning devices
On a two-lane or undivided highway, where should warning triangles generally be placed?
Answer: Within 10 feet and about 100 feet ahead and behind The standard pattern warns traffic from both directions: one device near the vehicle and one about 100 feet in each direction. Curves, hills, and obstructions may require placement farther away for warning. Study: General Knowledge — emergency warning devices
What should a driver avoid doing while crossing railroad tracks?
Answer: Shifting gears Shifting on the tracks can lead to a missed gear and a stalled vehicle. Select the proper gear before beginning the crossing. Study: General Knowledge — railroad crossings
Before crossing railroad tracks, what must a driver be sure of?
Answer: There is enough space to clear the tracks completely Never enter a crossing unless the entire vehicle can clear all tracks. A long combination needs more clearance than a passenger car. Study: General Knowledge — railroad crossings
What is the best general response to highway work zones?
Answer: Slow down early and follow signs and flaggers Work zones can have narrow lanes, workers, equipment, and sudden traffic changes. Reduce speed early and leave extra space. Study: General Knowledge — work zones
What is usually the safest choice when fog becomes too dense for safe driving?
Answer: Pull completely off the road at a safe place and stop If visibility is too poor, leave the roadway at a safe location rather than stopping in a traffic lane. High beams can reflect from fog and worsen glare. Study: General Knowledge — driving in fog
What does it mean to “overdrive” your headlights?
Answer: Driving too fast to stop within the distance you can see At night, speed must allow a stop within the illuminated roadway. Otherwise a hazard may appear too late to avoid. Study: General Knowledge — night driving
Answer from memory so your first score shows which topics need work.
02
Review the explanations
Return to the cited handbook section whenever an idea is unclear.
03
Retake after review
Aim for consistent mastery, not memorizing the position of an answer.
FACT-CHECKED STUDY BASIS
Official handbook sources
Questions are original study material based on the standard CDL manual topics used by state licensing agencies. Requirements and test formats can vary by state, so always confirm details in your current state CDL manual.
Important: This independent study site is not affiliated with FMCSA or any state DMV. It does not replace the official handbook or professional instruction.