Hydroplaning is an effect in which a vehicle's tires lose traction with the surface of the road and instead glide along a layer of water. There does not have to be a large amount of water on the road for this to occur. Hydroplaning can begin at speeds as low as 30 mph.

In vehicles with air brakes, the parking brake is controlled by a knob. The knob is pulled out to apply the brakes, and pushed in to release them.

Defects to check for when inspecting your vehicle's suspension system include cracked or broken spring hangers; missing or broken leaves in a leaf spring; and leaking shock absorbers. If you spot any of these issues, be sure to have them repaired.

The right lanes of a roadway are generally intended for vehicles traveling more slowly than surrounding traffic. If being slowed down by a heavy load, you should stay in the right lane.

Older trailers do not have spring brakes. This means that if the air supply in an older trailer's air tank has leaked away, there will be no working brakes connected to the trailer and its wheels will turn freely.

Tire load is defined as the maximum safe weight that a tire can carry at a specified pressure.

On a vehicle with one or more trailers, mirror adjustment can only be checked accurately if the trailers are straight. Mirror adjustment should be checked before the start of every trip.

You should approach every railroad crossing with the expectation that a train is coming. Do not rely on signals or your hearing to reliably tell you if a train is present. Always slow down when approaching a crossing. Never try to race a train.

To prevent a vehicle with manual transmission from rolling backward when you begin to move forward from a stopped position, you can partly engage the clutch before removing your foot from the brake pedal.

If you are experiencing a trailer jackknife, you can help your tires regain traction by releasing the brakes. Using a trailer hand brake while experiencing a skid will only cause the skid to continue.

Faster speeds create more heat in the engine and tires, so slow down to avoid dangerous overheating when the weather is very hot.

Slow down and be especially careful when driving in and around work zones, in places where the pavement drops off sharply at the edge of the road, when foreign objects are present on the road, and on freeway on- and off-ramps.

Vehicles with trailers are vulnerable to rollover due to the "crack-the-whip" effect, which is caused by rearward amplification. Rearward amplification varies from vehicle to vehicle, so it is important that drivers are aware of the rearward amplification of their specific vehicles.

If the low air pressure warning signal comes on while you are driving a vehicle with air brakes, you should immediately bring the vehicle to a safe stop while you are still able to control the brakes. Inspect and repair the brakes as soon as possible.

While driving, you should consistently check the road ahead for hazards. Develop a plan to deal with any hazards that could arise.

On flatbed trailers or trailers without sides, cargo must be tied down to keep it from shifting or falling in transit.

Tire load is the maximum weight that a tire can safely carry at a specified pressure. This will be stated on the side of a tire.

If you experience tire failure, you may hear the loud "bang" sound of a blowout or feel a heavy thumping or vibration in your vehicle. If steering begins to feel heavy, or if the rear of your vehicle begins to fishtail, you should stop to check your tires.

Before a trip, ensure that air in the air brake system reaches all trailers. Do this by waiting for air pressure to build, then sending air to both the emergency and service lines and opening the shut-off valves on the rear of the last trailer. If air escapes from the shut-off valves at the rear of the combination, the air is being supplied to the entire vehicle.

It is best not to avoid driving in fog. However, if you must drive under foggy conditions, be sure to decrease your speed.