Overloading can have bad effects on steering, braking, and speed control. Overloaded trucks have to go very slowly on upgrades, and they may gain too much speed on downgrades. Stopping distance increases. Brakes can fail when forced to work too hard.

Braking distance is the distance your vehicle will travel, in ideal conditions; while you are braking. At 55 mph on dry pavement with good brakes, it can take about 216 feet.

Most good drivers look at least 12 to 15 seconds ahead. That means looking ahead the distance you will travel in 12 to 15 seconds. At lower speeds, that's about one block. At highway speeds it's about a quarter of a mile.

You will be put out-of-service for 24 hours if you have any detectable amount of alcohol under .04%.

Baffled liquid tanks have bulkheads in them with holes that let the liquid flow through. The baffles help to control the forward and backward liquid surge. Side-to-side surge can still occur.

There are blind spots you can't see. That's why a helper is important. The helper should stand near the back of your vehicle where you can see the helper.

If the shoulder is clear, stay on it until your vehicle has come to a stop. Signal and check your mirrors before pulling back onto the road.

When your drive wheels have poor traction, the retarder may cause them to skid. Therefore, you should turn the retarder off whenever the road is wet, icy, or snow covered.

The weight of a cargo van changes its height. An empty van is higher than a loaded one. That you got under a bridge when you were loaded does not mean that you can do it when you are empty.

You must have at least 4/32-inch tread depth in every major groove on front tires and at least 2/32-inch on other tires

Heavy vehicles are often tailgated when they can't keep up with the speed of traffic. This often happens when you're going uphill. If a heavy load is slowing you down, stay in the right lane if you can. Going uphill, you should not pass another slow vehicle unless you can get around quickly and safely.

No matter how small the cargo, it should have at least two tie-downs.

Federal and state inspectors also may inspect your vehicles. If they judge the vehicle to be unsafe, they will put it "out of service" until it is fixed.

It takes a typical tractor-trailer unit at least 14 seconds to clear a single track and more than 15 seconds to clear a double track.

Gross Combination Weight (GCW) is the total weight of a powered unit, plus trailer(s), plus the cargo.

¾ second to 1 second.

Short breaks can keep you alert. But the time to take them is before you feel really drowsy or tired. Stop often. Walk around and inspect your vehicle. It may help to do some physical exercises.

Shipping papers listing a hazard class, hazardous material labels on the cargo, or placards on the vehicle all show the driver that the load contains hazardous material.

During the pre-trip inspection the lights and covers need to be working and clean, wiper blades in good condition, and the cargo needs to be secured.

If you must stop on or by a one-way or divided highway, place warning devices 10 feet, 100 feet, and 200 feet toward the approaching traffic.

¾ second to 1 second. At 55 mph this accounts for 61 feet traveled.

A hazard is any road condition or other road user (driver, bicyclist, pedestrian) that is a possible danger.

For an en-route Inspection. Check the, tires, wheels, and truck body for signs of heat whenever you stop during a trip. Also check for cargo securement at each stop.

Tire problems include: too much or too little air pressure, bad wear, at least 4/32-inch tread depth on front tires, 2/32 inch on all other tires, no fabric should show through the tread or sidewall, cuts or other damage, tread separation, dual tires that come in contact with each other or parts of the vehicle, mismatched sizes, radial and bias-ply tires used together.

One good rule says you need at least one second for each 10 feet of vehicle length at speeds below 40 mph. At greater speeds, you must add 1 second for safety.

The first step is to get the vehicle off the road and stop. In doing so: park in an open area, away from buildings, trees, brush, other vehicles, or anything that might catch fire. Don't pull into a service station!

With the stab braking method, you apply your brakes all the way and release brakes when wheels lock up.

Once the vehicle is in the proper low gear, the following are the proper braking techniques: Apply the brakes just hard enough to feel a definite slowdown, when your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. When your speed has increased to your "safe" speed, repeat.

If for any reason you get stuck on the tracks, get out of the vehicle and away from the tracks. Check signposts or signal housing at the crossing for emergency notification information. Call 911 and give the location of the crossing using all identifiable landmarks, especially the DOT number, if posted.

Air pressure increases with temperature. Do not let air out or the pressure will be too low when the tires cool off.

Brake fade results from excessive heat causing chemical changes in the brake lining, which reduce friction, and also causing expansion of the brake drums

Preventing drowsiness before a trip: Get adequate sleep (8 to 9 hours), prepare route, , schedule trips for the hours you are normally awake, drive with a passenger, avoid medications that cause drowsiness.

If the shoulder is clear, going right may be best. No one is likely to be driving on the shoulder, but someone may be passing you on the left. You will know if you have been using your mirrors. If you are blocked on both sides, a move to the right may be best. At least you won't force anyone into an opposing traffic lane and a possible head-on collision.

If you are drowsy, the only safe cure is to get off the road and get some sleep. If you don't, you risk your life and the lives of others.

Converter dollies built on or after March 1, 1998, are required to have antilock brakes. These dollies will have a yellow lamp on the left side of the dolly.

Whenever you are about to pass a vehicle, pedestrian, or bicyclist, assume they don't see you. They could suddenly move in front of you. When it is legal, tap the horn lightly or, at night, flash your lights from low to high beam and back.

Before you change lanes, you must first make sure that no vehicles are hiding in your blind spots.

Gently put on the brakes. This presses linings against brake drums or discs and keeps mud, silt, sand, and water from getting in.

Because you cannot see everything behind your vehicle, backing is always dangerous. Avoid backing whenever you can. When you have to back, here are a few simple safety rules: Start in the proper position, look at your path, use mirrors on both sides, back slowly, back and turn toward the driver's side whenever possible, and use a helper with clear hand signals whenever possible.

A DOT physical exam is valid for up to 24 months. The medical examiner may also issue a medical examiner's certificate for less than 24 months when it is desirable to monitor a condition, such as high blood pressure.