Steering wheel play of more than 10 degrees (about two inches of movement at the rim of a 20-inch steering wheel) can make it difficult to steer.

When inspecting your vehicle's engine, check the belts for tightness and excessive wear. The amount of "give" that is safe for each belt in a given engine will vary, so learn what is appropriate for your vehicle.

Railroad-highway crossings may be difficult to cross if you are pulling a trailer with low underneath clearance. In particular, both low-slung units and single-axle tractors pulling long trailers are especially challenging to drive over raised crossings.

When performing a visual check of coupling devices, you should make sure there is no space between the upper and lower fifth wheel. Ensure that the locking jaws are securely closed around the kingpin.

It is important to observe other drivers' behaviors and identify clues that indicate when person could be driving impaired. Drivers who have had too much to drink, are sleepy, are on drugs, or are ill can present hazards to other drivers. A person driving with their window open in cold weather may be impaired.

When parking a double or triple, you should select a parking spot where you can pull forward when leaving. Be aware of the arrangement of the parking lot to avoid the need for a long and difficult exit.

If you begin to feel sleepy while driving, the only safe response is to stop driving and get some sleep. Attempting to fight off exhaustion is dangerous and a major cause of fatal crashes. Stimulants are not a safe solution because they may help keep you awake but will not make you more alert. Once stimulants wear off, you will be even more tired than you were originally.

To keep an engine fire from spreading, you should turn off the vehicle's engine as soon as possible. Do not open the hood if you don't have to.

A leaking exhaust system can introduce carbon monoxide, which is poisonous, into the cab or sleeper berth.

If a vehicle is equipped, an application pressure gauge shows how much air pressure is being applied to the brakes. This gauge can help a driver identify if their brakes are beginning to fade.

Shut-off valves are used in air supply lines to control the passage of air from one trailer to another. The rear shut-off valve should always be closed to prevent air from leaving the braking system.

A vehicle that is equipped with air brakes must also be equipped with a supply pressure gauge. This gauge tells the driver how much air pressure is in each of the vehicle's air tanks.

Never use the trailer hand valve while operating your vehicle. Using the trailer hand valve while driving can cause your trailer to skid.

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.

Check each slack adjuster after parking on level ground, setting wheel chocks, and disengaging the parking brake. Pull the slack adjusters to make sure they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.

In an air brake system, the application pressure gauge shows how much air pressure is being applied to the brakes. Not all vehicles with an air brake system have this gauge.

If a tractor is equipped with an Anti-Lock Braking System (ABS) but the trailer is not, the risk of jackknifing will be reduced and the driver should still be able to maintain steering control. If only the trailer is equipped with ABS, it is less likely that the trailer will swing out to one side.

When performing a static leakage test on a double combination vehicle with air brakes, the leakage rate should be no more than 3 psi in one minute. If the air leaks from the air brake system at a quicker rate, the vehicle should not be driven because something likely needs to be repaired.

Before coupling together a tractor and a trailer, you should make sure the trailer is at the proper height. If the trailer is too low, the trailer nose may be damaged. If the trailer is too high, it may not be able to couple correctly.

All trailers and converter dollies manufactured on or after March 1, 1998 must be equipped with Anti-Lock Braking Systems (ABS).