To help prevent a rig from rolling over, you should keep the weight of the cargo as close to the ground as possible when loading. You should also drive slowly around turns.

Increasing your vehicle's speed will increase your vehicle's striking power and braking distance. Doubling your vehicle's speed from 20 to 40 mph will quadruple its braking distance.

Braking after a tire fails can result in a loss of control. Stay off your brakes, if possible, until your vehicle has slowed considerably.

Backing a commercial motor vehicle is always dangerous because you cannot see everything behind you. When backing, make frequent checks of the mirrors on both sides of the vehicle. Use a helper whenever possible.

To avoid becoming fatigued on a long trip, you should take a break after every 100 miles or two hours of driving. Driving through the night, or during any other time when you would normally be asleep, raises the danger of fatigue.

Oil pressure should come up to normal within seconds of starting the engine.

The easiest way to become aware that your trailer has begun to jackknife is to observe it in your mirrors. Checking your trailer in your mirrors will also allow you to spot any skidding at the earliest possible moment.

If your brakes fail while you are driving downhill, you should first look for an escape ramp to stop your vehicle. If no ramp is available, you should look for an alternative place to bring your vehicle to a stop, such as an open field or side road that flattens out or turns uphill.

Parking brakes should be used whenever you park. If necessary, chock your wheels.

If the coolant temperature gauge goes above the highest safe temperature, you should stop driving as soon as possible and try to figure out what is wrong. There could be an issue in your vehicle that could lead to engine failure and possibly a fire.

While regular mirror checks should be part of your normal scanning routine, be especially sure to check your mirrors when changing lanes.

During a trip, you should regularly make checks to ensure that your vehicle is operating properly. Check the instrument panel and gauges; look at your mirrors; and examine the tires, cargo, and lights. Use all of your senses and be alert for anything that could be an early indication of trouble.

Never assume that the posted height on a bridge or other overhead object is correct. Even if it was accurate when posted, things may have changed that affect clearance, either permanently (such as a repaving of the road) or temporarily (such as packed snow on the road).

Black ice is a layer of ice that is thin and clear enough for the road to be visible through it. The surface will look like a wet road. Always be alert to black ice if the road looks wet when the temperature is below freezing.

When driving on a wet road surface, the risk of hydroplaning is increased if your tire pressure is too low or your tire tread is too worn. If you begin to hydroplane, release the accelerator and push in the clutch to slow down.

Gravity causes a vehicle's speed to increase when traveling on a downgrade. Adjust your speed before reaching a downgrade.

Defects in an exhaust system are very dangerous because they can cause poisonous fumes to enter the cab or sleeper berth.

In an air brake system, the air tanks must be periodically drained to remove accumulations of water and compressor oil. If water is not removed, it could freeze in cold weather and cause brake failure.

If a vehicle has anti-lock brakes on just one axle, the driver will still have more control during braking than they would without any anti-lock brakes.

The emergency air line (also known as the supply line) has two functions. The first is to supply air to the trailer air tanks, and the second is to control the emergency brakes on combination vehicles.