On many vehicles, multi-speed rear axles and auxiliary transmissions are used to provide extra gears.

The aisles and stairwells of a bus should always be kept clear. Luggage and freight must be placed in a location that allows passengers to exit through any window or door in the event of an emergency.

When backing a truck, always use the mirrors on both sides of the vehicle. Have someone help you whenever possible.

It is important to inspect your tires before every drive. Rust around wheel nuts may indicate that they are loose.

If you are not sure which kind of extinguisher should be used on a fire in your vehicle, particularly a hazardous materials fire, you should wait for the firefighters to arrive and allow them to extinguish it.

Distractions that can affect safe driving can be classified as physical (such as reaching for an object), mental (such as talking with passenger), or both (such as talking on a hand-held phone).

Texting while driving is particularly dangerous because it is both a mental and physical distraction to the driver. In addition to diverting a driver's mental attention away from the road, texting requires a person to remove at least one hand from the vehicle's controls.

When doing a pre-trip inspection during the winter, you should pay extra attention to the coolant level and amount of antifreeze; the defrosting and heating equipment; the wiper blades and windshield washer; the tires and tire chains; the lights and reflectors; the windows and mirrors; the hand holds, steps, and deck plates; the radiator shuttles and winterfront; and exhaust system.

To let drivers behind you know that you plan to slow down, lightly tap your brake pedal a few times to flash your brake lights. It is important to communicate your intentions to other drivers.

When involved in an accident, you should protect the area, notify authorities, care for the injured, collect required information, and report the accident. You can lose your license for leaving the scene of an accident.

Black ice is a thin layer of ice that is clear enough for the road surface to be seen through it. A road covered in black ice may look like it is merely wet. You should be very careful when temperatures are below freezing and the road looks wet.

Before backing up, you should get out of your vehicle and look at your line of travel. Check your clearance to the sides and overhead.

The doors of a trailer should be not be opened in the event of a cargo fire, especially if the cargo includes hazardous materials. Opening trailer doors would increase the fire's oxygen supply, potentially causing the fire to increase in size.

When inspecting a trailer coupling, you should make sure the fifth wheel locking jaws are closed around the shank of the kingpin, not the head of the kingpin.

Drivers who are engaged in conversation with passengers may be distracted from the task of driving. Use extra caution when driving near distracted drivers.

To reduce the risk of becoming fatigued on a long trip, you should stop to take a break at least once for every two hours or 100 miles driven.

Missing clamps, spacers, studs, or lugs are dangerous, as are mismatched, bent, or cracked lock rings. Be sure your tires and rims are in good condition before operating your commercial motor vehicle.

When inspecting your tires, verify that there is at least 4/32 of an inch of tread depth in every major groove on the front tires, and tread depth of at least 2/32 of an inch on the other tires. Tires on the same vehicle should all be the same size.

On a wet road, it is possible for a vehicle's tires to lose traction with the road surface and begin to glide along on the layer of water. This is referred to as hydroplaning. Hydroplaning can occur at speeds as low as 30 mph.

If you are not certain that your vehicle will fit under overhead objects, you should slow down and take a different route, if possible.