South Dakota CDL: General Knowledge Practice Test

Not quite. The answer is When driving in very hot weather, you should inspect your tires every two hours or every 100 miles.

Air pressure increases with temperature. In very hot temperatures, a tire may blow out or even catch fire. Check your tires every two hours or 100 miles. If any tires are too hot to touch, remain stopped until they cool off.

Not quite. The answer is select a gear that will keep your vehicle at a safe speed on steep downgrades.

If you keep applying the brakes to control your speed on steep downgrades, the brakes may fade (lose their effectiveness). Instead, shift into a low gear. This will generate a braking effect to slow the vehicle, known as engine braking. The lower the gear, the greater the engine braking effect. Apply the brakes only when engine braking is insufficient or you want to stop.

Not quite. The answer is 43%

Federal regulations impose maximum weight limits on CMVs traveling on interstate highways. The maximum allowable GCWR is 80,000 pounds. The single axle weight rating is 20,000 pounds, and the tandem axle weight rating is 34,000 pounds. This weight rating is for typical tandem axles that are spaced 40 to 96 inches apart, from center to center. 34,000/80,000 = about 43%. If both the drive tandems and trailer tandems are each carrying their maximum allowable weight of 34,000 pounds, that leaves only 12,000 pounds (about 14% of the weight) for the steering axle, even though the maximum allowable weight is 20,000 pounds.

Not quite. The answer is A thin layer of ice clear enough that you can see the road underneath it

Black ice is a thin layer of ice that is clear enough for you to see the road beneath. Black ice is treacherous because it makes the road only look wet, not icy.

Not quite. The answer is Yes.

Under federal regulations, you may not drive a property-carrying motor vehicle unless every passenger is wearing a seat belt (if the seat is so equipped).

Source: 49 CFR 392.16

Not quite. The answer is Trucks with a high center of gravity can roll over at the posted speed limit for a curve.

Trucks with a high center of gravity are much more likely to roll over on a curve, even if they are not exceeding the posted or recommended speed limit. When driving such a vehicle on a curve, slow down well below the posted speed limit.

Not quite. The answer is Exiting a tunnel

Inside a tunnel, you don't feel the effect of crosswinds pushing you sideways. But once you emerge from the tunnel into an open space, the crosswinds will hit you. If your vehicle is traveling alongside another vehicle, there is some chance that the crosswinds will push one of the vehicles against the other.

Not quite. The answer is Windshield washer antifreeze should be used.

Prevent your windshield from freezing in cold weather. Fill your windshield washer reservoir with a windshield washer antifreeze that is rated for the cold temperatures in which you expect to be driving.

Not quite. The answer is A burning tire should be cooled with water.

If the cargo is on fire, opening the trailer's doors will let more oxygen into the trailer and feed the fire. If a tire is on fire, it should be cooled, preferably with a lot of water.

Not quite. The answer is Both of the above

The classic sign of a tire blowout is a loud "bang" sound. However, if you're driving a long vehicle and a rear tire blows out, you may not hear the sound. In this situation, a thumping or heavy vibration may be the first sign you get that a rear tire has failed. Also, your vehicle may start to fishtail. On the other hand, heavy steering probably indicates that a front tire has failed.

Not quite. The answer is do both of the above.

Backing a large CMV is potentially hazardous. Before you start to back up, check your intended path of travel. Exit the cab and walk around the vehicle. Check your clearance to the sides and overhead, in and near the path of your vehicle. To make backing up easier and safer, turn toward the driver's side so you can watch the rear of your vehicle through your window.

Not quite. The answer is It takes 14 seconds to clear a single track and more than 15 seconds to clear a double track.

A typical tractor-trailer will take at least 14 seconds to fully clear a single railroad track and more than 15 seconds to fully clear a double track.

Not quite. The answer is Look toward the right edge of your lane or the right edge of the road.

If an oncoming vehicle has not dimmed its headlights, don't retaliate with your own high beams. Instead, slow down, keep right, look away from the vehicle, and steer by the right edge of the road until the vehicle has passed you.

Not quite. The answer is 2

According to CVSA's North American Standard Out-of-Service Criteria, the vehicle will be placed out of service if 20% (rounded up to the next whole number) or more of its brakes are found to be defective. For a 5-axle tractor-trailer, which has 10 brakes, if 20% × 10 = 2 or more brakes are defective, the vehicle will be placed out of service. In this context, defects include a brake shoe or brake pad that fails to contact the brake drum or rotor when the service brakes are applied, or an audible air leak at a brake chamber.

Not quite. The answer is perception

The distance that your vehicle travels from when your eyes see a hazard to when your brain finally recognizes it as a hazard is called the perception distance.

Not quite. The answer is where the rear of your vehicle is while you make turns.

Before driving your vehicle, adjust your mirrors to show parts of your vehicle as well as what's around your vehicle. During your trip, you can use your mirrors to keep an eye on your tires and open cargo if any. When you turn, check your mirrors to make sure that the rear of your vehicle isn't hitting anything. If you're pulling a trailer, use your mirrors to keep an eye on it. If it starts to jackknife, you'll be able to spot it in your mirrors.

Not quite. The answer is do both of the above.

A front-end header board is located behind the cab. The header board prevents cargo from moving forward (and possibly injuring you) in the event of a crash or sudden stop. Check to make sure that the header board is secure, upright, and undamaged (no dents, no corrosion, no missing rivets, etc.).

Not quite. The answer is Clear

Fresh Diesel Exhaust Fluid (DEF) looks like clear water. If the DEF fluid in a vehicle's DEF tank looks cloudy, is any other color but clear, or has contaminants floating in it, the fluid has gone bad and must be replaced.

Not quite. The answer is Rental truck drivers are often not used to the limited vision and pose a hazard.

A car driver who has never driven a truck before will be unused to a rental truck's size and limited view toward its sides and rear. This lack of truck driving experience makes a rental truck a hazard on the road.

Not quite. The answer is Pulling forward while backing a trailer to reposition it

When backing a vehicle, especially a tractor-trailer, you may need to pull forward to straighten the vehicle or reposition it for a better angle. This corrective maneuver is called a pull-up. Note, however, that you should be able to back your vehicle successfully without too many such corrections. During your CDL skills test, your examiner may penalize you for too many pull-ups.