If there is enough water on the road, hydroplaning can occur at speeds as low as 30 mph. It is most likely if the tires' air pressure is too low or if tires' tread is worn.

If you use your brakes too much when traveling on a steep downgrade, they may overheat and become less effective. To avoid causing your brakes to overheat on a steep hill, you should rely on engine braking.

Mirrors should be checked prior to the beginning of a trip. On a vehicle with a trailer, mirror adjustment can only be checked accurately if the connected trailer is straight.

If possible, you should avoid all cell phone distractions by turning it off before starting a trip and leaving it off until you reach your destination.

Most cases of hydraulic brake failure come from one of two causes. The brakes may fail due to a loss of hydraulic pressure or due to overuse on long hills, causing the brakes to fade.

When driving under foggy conditions, lights cannot be taken as a reliable indication of where the road is. The lights may be coming from a vehicle that has pulled off the road.

It is important to know the maximum air loss rate that is safe for your specific vehicle. A double combination vehicle should have a leakage rate no higher than 4 psi in a minute during an applied leakage test.

At the end of each day of driving, you may be required to make a written report on the vehicle or vehicles driven. Be sure to make note of any issues that could affect the safety of the vehicle or that could lead to a mechanical breakdown.

When inspecting a vehicle, you should verify that your dual tires do not come into contact with one another, or with any other part of the vehicle.

While driving, regular mirror checks are essential to remaining aware of the traffic around you. Mirrors are also essential to helping you spot possible problems on your own vehicle.

When checking the power steering fluid during the vehicle inspection test, you must be able to indicate where the power steering fluid dipstick is located and show that there is an adequate amount of power steering fluid in the engine compartment. The fluid level must be above the refill mark.

During a pre-trip inspection, you should check for emergency equipment, including spare electrical fuses; three red reflective triangles, six fuses, or three liquid burning flares; and at least one properly charged and rated fire extinguisher.

Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Manually operated air tank drains must be opened daily to remove this build-up.

Bus passengers should not be allowed to leave baggage in any doorway or aisle. Baggage and freight must be secured in a manner that will prevent damage, allow the driver to move freely and easily, allow riders to exit by any window or door in an emergency, and protect riders from injury if the items fall or shift.

On a vehicle with air brakes, pressing and releasing the brake pedal unnecessarily may let air out of the braking system faster than the compressor can replace it. This may cause the system's air pressure to become too low and the brakes to stop working.

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.

If you must stop and park on the side of the road, make sure to turn on your emergency flashers. This is especially important at night. Taillights are not an adequate when alerting other drivers because the drivers may mistakenly think your vehicle is moving normally and collide with it.

When driving, you should regularly check your mirrors, both to be aware of traffic and to check for problems on your own vehicle.

To avoid hitting someone or something behind you, it is important to ensure that your vehicle does not roll backwards when starting from a stop. If your vehicle has a manual transmission, partly engage the clutch before taking your foot off the brake.

Because air expands when hot, tire pressure increases as temperatures increase. This can sometimes result in tire failure. Consistently check your tire pressure when making a trip in hot weather.