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TRAILER LOADING AND TOWING GUIDE
INTRODUCTION
The purpose of this page is to
compile a list of information that could
be useful and helpful when towing or loading a trailer. There are a
number of variables that lead to safely towing a trailer and can't be
written into a few simple rules. The information listed here has
been compiled from our knowledge and other sources. It is important
to know how to accurately load a trailer so that it can be safely towed at
reasonable speeds.
The following
are some of the problems you may encounter and some basic
rules that you need to know. It is up to you to decide what will
work and add the common sense it takes to safely tow a trailer. If a
trailer doesn't tow properly when all the basic rules have been followed,
the answer can be very complex, because the result can be an oscillating
trailer. This is usually caused by a trailer that is "tail heavy",
and adding more tongue weight will cure the problem. If it doesn't,
you need expert help. The moment a rig shows any tendency in this
direction you should slow down and get some expert help on it.
Oscillations are very complex because they can be the result of several
components working in unison. Speed and wind are two of these
components, so you should never drive faster to try and eliminate the
oscillation or any other problem. You should start off by towing the
trailer without any load. If a problem such as this exists, go to
your hitch shop or the dealer that sold the trailer. The information
that is covered here cannot solve problems such as these if the basic
rules have been followed and oscillation still occurs. It can be
very dangerous to experiment with an ill handling rig,
especially on a public road.
THE TOW VEHICLE
If you haven't
already purchased a tow vehicle you can customize
it's specifications to your towing needs. Most likely, however, you
already have the vehicle you will be using to tow and have based your
trailer purchase on its capabilities. It might be wise to ask
yourself at this point if the tow vehicle is really big enough to have the
brakes and suspension it takes to safely tow your trailer. There
isn't any good way to overcome a problem such as this short of trading up
to a vehicle with more capacity. If the suspension isn't heavy
enough, the brakes probably leave something to be desired. You can
get this type of information from manufactures of trailers, trucks, and
automobiles but they tend to be optimistic, quoting maximum capacities
rather than recommended capacities. Remember also that a half-ton
pickup may be able to carry 1000 pounds of weight in the bed, but probably
cannot support 1000 pounds at the hitch without special modifications to
the suspension. So if you hook up your twenty-four foot cargo
trailer to your nice, new half-ton pickup and the headlights are aimed at
birds roosting in the trees, there should be a clear message that
something is wrong.

You can't always
correct the problem by moving the load if the tow
vehicle isn't capable of handling the required hitch weight. Moving
the load back in the trailer could make for a very unstable and dangerous
condition, and leaving too much weight on the hitch can also cause a
dangerous situation where the tow vehicle doesn't have enough weight on
the front wheels to control your rig. When you hit the brakes, the
trailer dives lifting the front end even more, and you lose most of your
braking and steering at the same time. Several types of weight
redistribution hitches are available (contact our
parts department for additional information) that can
dramatically help your handling by spreading the forces to both axles, but
they can not compensate for inadequate towing capacity or overloading.

(LEFT) Trailer
"Dive" during heavy braking increases the
effect of tongue weight.
(RIGHT) Weight distributing hitch transfers loads to frame and to both
axles of tow vehicle for safer stops and smoother ride.
Talk to the GGT service
department about your particular needs.
This leads to the first and most basic rule of trailer towing:
"The
tow vehicle and hitch must be capable of
safely handling at least 15% of the gross weight of the trailer (total
weight of trailer plus contents). Fifth wheel trailers usually have up to
25% of the gross weight on the hitch."
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VEHICLE AND TRAILER BRAKES
Although it is beyond
the scope of these instructions to cover
everything, it is important to mention brakes. If you can't get to
the top of a hill from lack of power you can usually pull over and it may
cause an inconvenience but not a disaster. If the brakes fail going
down a hill you have a problem that can cause a disaster. You can't
have too much brake. Disk brakes are better than drum brakes.
Four electric brakes on your trailer are better than two. New pads
are better than old pads. You should be able to stop your rig on a
hill without the trailer brakes. If you can't, you'd better pay a lot more
attention to that corroded connector you have been hooking up your trailer
with.
When learning,
get on a lonely road without any traffic and try
practicing panic stops. Of course, you shouldn't just slam on your
brakes. You should try to slowly shorten your stopping distance by
applying more pressure. Don't take it to the point that you lose
control, just enough to get a feeling what it takes to make a quick stop
and the distances involved. As a result of this exercise you will
find yourself leaving more room in front of your vehicle. Don't ride
the brakes going down hills as this overheats brakes, causing them to lose
effectiveness. Use the engine and lower gears to control the
downhill speed on long hills. Learn how electric brakes work and how
to adjust the modern day controllers that actuate them. Remember
that the slightest pressure to the brake pedal will apply the electric
brakes. Keep your foot off the brake pedal unless you intend to use
them. They shouldn't be allowed to be on for extended periods.
The basic drag of these brakes are set with the control, not how hard you
press the pedal. A pendulum type control will electronically adds
more brake as you stop, but if you have your controller turned all the way
up, the slightest pressure on the pedal could lock your trailer brakes.
THE HITCH
Before
towing anything, have your hitch inspected by a qualified
hitch installation company, and have them determine what the maximum
tongue weight can be. This is usually 10% of the hitch's rated
capacity. Note, the correct term is hitch, not ball. A
ball is rated by its own towing capacity. A hitch is rated by not
only its towing capacity but also by the tongue weight. Again, the
safest way to accomplish this is to take your vehicle to a shop that
specializes in installing hitches. If you have a bumper type hitch,
don't tow anything your wife can't lift onto the ball. The biggest
error you can make is "cheaping out" and not going to a qualified shop.
THE TRAILER BALL AND SAFETY CHAINS

The ball should
be located so the trailer sits level when connected to
the tow vehicle. The vehicle should be able to accept this weight
without a major change of attitude. The ball should be lightly
greased so the hitch rotates smoothly on it. Safety chains should be long
enough for tight turns and be crossed (right to left and left to right).
This will help create a "saddle" if you have a tongue failure and will
help maintain control while stopping. Don't allow these chains to
drag on the pavement, because they can be ground to an unsafe condition in
a very short amount of time. Always inspect the hitch and tongue for
cracks when hooking up. Rust is your enemy and can cause premature
failures. Check lights and brakes each time the trailer is hooked
up. Try to do things in the same order each time and use a
checklist. Don't forget to retract the jack. Don't ever hook a
trailer up half way or you may forget to finish the job. Don't start
if you can't finish, and don't ever leave the receptor pin out for a
minute.
TRAILER LIGHTING AND CONNECTIONS

All your lights
must work to be legal and safe. The weakest link
is the connector. They corrode easily and need constant attention to keep
the system working. (Be careful when cleaning connectors not to
short them out.) The wiring to the connector should be carefully
routed so that it can't come apart in tight turns or chafe through and
short out. Remember, electric brakes also run through this
connector. Have an observer confirm your brake lights, turn signals,
and running lights are working properly each time you hook up.
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TIRES AND WHEEL BEARINGS
TIRES...Tires have to be
checked frequently with a trailer because a flat can go unnoticed on
multiple axle trailers while it is being towed. Running with a flat
can cause it to catch fire and burn up your rig. With multiple axles
or tandem wheels it is hard sometimes to see a flat tire as the other
tires are supporting the weight of the rig and the flat spot is less
noticeable. A quick check can be made by "thumping" each tire with a
tire iron or rod to make sure they all sound the same. Each time you
gas up, walk around the trailer and give a quick check by feeling each
tire with your hand. A tire that is getting low will be hotter than
the rest. There is no substitute, however, for actually measuring tire
pressures to make sure they are all within safe limits. This should
definitely be done before each trip.
NOTE: The most
common causes of tire failure are overloading and under
inflation. Both result in excess flexing of the sidewall which
causes heat buildup, excessive uneven wear, and eventual failure.
Continuing to run with a flat can cause it to catch fire.
WHEELS AND LUG NUTS...
Trailers have higher wheel loading than
passenger cars or trucks. Tandem axles do not steer, and wheels are
subjected to high twisting side loads in tight, slow turns. This
causes the wheel to flex which tends to loosen wheel lug nuts over time.
Always check lug nut torque before each trip. A suitable torque
wrench only costs about $30 and is a worthwhile investment considering the
value of your trailer. Aluminum wheels are more likely to have the
lug nuts loosen then steel wheels, especially after the initial
installation.
Wheel lug nut
torque is usually much higher than that specified for
passenger car wheels. Check your particular trailer's recommended
specifications. Most are in the 90-95 ft.-lb. range. On a new
trailer, check the torque on all wheels after the first 25-50 miles of
towing. Also recheck any wheel that has been removed and replaced
after towing 25 to 50 miles. Do not drive a loaded trailer with a
missing lug nut or damaged lug bolt.

Torquing order
for various wheel lug nut patterns as
suggested by a trailer manufacturer in their owner's manual.
Wheel lug nuts
are usually torqued in a "star
pattern" pattern for 5- and 10-bolt wheels, crossing over to
opposite sides as you work around the wheel. A "cross" pattern is
used for 4-, 6- and 8-bolt wheels. Shown above are some suggested
orders for tightening nuts on various bolt patterns. Using the
numbers on the above diagram, a popular alternate for the 5-bolt pattern
would be a 1-2-5-4-3 "star pattern".
WHEEL BEARINGS...
Axle wheel bearings also occasionally need
attention. Feel with your hand at the hub to check for one that may
be running hotter than the rest. (Be careful. If the bearing is
adjusted too tight or is running without grease it can get
VERY hot!) A hot bearing needs
immediate attention. Most often either more grease or proper
adjustment will ease the problem, but replacement may be necessary.
Boat trailers are a particular source of wheel bearing problems as they
are often put in and out of the water. A warm bearing that is
suddenly cooled by being immersed in water tends to suck water into the
inside as the air cools and shrinks. The water causes the bearings
to rust and fail.
RECOMMENDED HITCH WEIGHT PERCENTAGES
| TYPE OF TRAILER |
PERCENT OF WT. ON TONGUE |
| Single Axle |
10% minimum/15% maximum |
| Tandem Axle |
9% to 15% |
| Travel Trailer |
11% to 12% |
| 5th Wheel/Gooseneck |
15% to 25% |
PLACING THE LOAD
It would be
overly simplistic to say, "put the heavy items over the
axles". Sometimes a lot of little items can far outweigh one
big one. Don't put big, heavy items in a place where they can't be
securely tied down. A glued down rug makes a great floor for a cargo
trailer because things tend to stay put and don't slide around. Of
course, it would be easy to say everything should be securely tied down
but it would be also unrealistic. Start with top heavy items if you
have them. That's usually a good place to start because you must
have plenty of room available to properly tie them down. Tying them
straight down is not secure enough. They need to be tied off at
several angles or they could fall over in an abrupt change in speed or
direction. You need room to accomplish this. Smaller items can
be used to fill the spaces around them later.
The GGT Parts department carries a large selection of tie down straps and
securing devices to assist with these tasks.
Once you have
the heavy items located, check the tongue weight with a
scale. If the load is radically off, make the changes necessary to
get close. The smaller items can be loaded in such a way that they
balance out the load. They should be located so that they will stay
put. Placing them next to items that have already been tied down
helps, but your main concern should be to not lose the balance of the
trailer. Don't forget you can also get one side of a trailer a lot
heavier than the other without a little planning. This can cause a
very serious problem when cornering, even causing the trailer to turn over
in a sudden turn.
Top heavy loads
can cause problems not only in cornering but also in
hard braking. They have a tendency to make the trailer "dive" in
hard braking conditions. This suddenly increases tongue weight and
can decrease front axle loading just when you need steering and those big
front disc brakes the most. Center top heavy items or arrange
the remainder of the load to act as a counter weight to minimize this
effect.

Top heavy
loads can cause trailer "dive" under hard
braking, possibly reducing steering and braking control.
Never place
heavy objects on add-on devices hung on the rear bumper or
placed across the tongue frame. A bicycle may be fine to hang out in
back, but not a motorcycle. This places heavy objects where they
will dramatically effect handling in corners or bumps. Heavy weights
placed well behind the axle can also aggravate swaying in turns.
It is not possible
to cover every conceivable loading or trailering
situation. The best advice is to use good common sense and to always
allow plenty of margin for safety. The purpose behind this text is
to try to give you the necessary information to make intelligent, informed
decisions when loading. The ultimate responsibility for using that
information correctly lies with you and you alone.
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DETERMINING MAXIMUM GROSS TRAILER WEIGHT
Your trailer's
springs, axles, tires and chassis were all designed
to handle a certain maximum load. This load consists of the empty
trailer itself, plus the added weight of cargo that you add. This is
called the Gross Vehicle Weight Rating or GVWR. In addition, each
axle has a maximum weight that it was designed to support. This is
called the Gross Axle Weight Rating or GAWR. The total of all axle
loads plus the tongue weight should not exceed the GVWR.
Remember:
The GVWR is only as much as the weakest link.
Look at your tire ratings as they tend to be the weakest link. Add
up all the tire capacities to determine the total GVWR for the trailer.
CARGO CAPACITY = GVWR - Empty Trailer Weight
Overloading
a trailer beyond its rated capacity, even though it may be
well balanced and seem to handle fine, is a very dangerous practice.
Eventually something is bound to fail with dramatic and unpleasant
results. Overloading places excess strain not only on your tow
vehicle causing possible failures at the hitch or in your capacity to
safely bring it to a stop in an emergency, it also overloads the trailer's
frame, axles, bearings and tires.
Be leery of
home-made trailers. It is amazing how many bad ideas
can be incorporated into this group. Do you really want to risk
lives, your own included, to save a few bucks on a trailer? How many
trailers have you seen fishtailing down the road that were manufactured by
a credible company? Probably not many. If you now own an
ill-handling, no-name misfit, either get it fixed by a professional or get
rid of it by junking it. It's unethical to sell or use a trailer
that could cause a serious accident. Good cargo trailers are usually
designed to maintain a proper tongue weight if they are loaded evenly.
It is up to
you to find out what the maximum gross weight of your
trailer should be. Trailers made by reputable manufacturers should
contain a tag or instructions which list loading limits. This can be
more of a problem if you have a trailer built twenty years ago by a
company that no longer exists and the tag or instructions are missing.
If you cannot obtain actual figures from the original manufacturer, take
it to a reputable trailer sales or repair facility and get an expert to
give his best estimate of its capacity.
Load your
trailer well below the maximum for the first tow with a new
rig or while you are learning. Keep track of the weights of the
individual items as you load them. When in doubt guess high.
Using a scale, adjust the load so that you have around 12% to 15% of your
best estimated total weight on the hitch. Attach the trailer to the
tow vehicle and note how much the rear end drops. (If it looks
excessive, check the tow vehicle's load capabilities again.)
WEIGHING THE TRAILER

Though it is
not necessary to weigh your trailer every time you load
it, it is a good idea in the beginning to have a good cross-check to your
estimates. Once you have a feel for it, a good estimate is usually
close enough unless you are loading to near your trailer's maximum limits.
A 1000-pound error in total weight is only a 150 pound (15%) error in
tongue weight.
Weigh the trailer
by having just the trailer wheels on the scale.
You do not need to disconnect it from the vehicle. Add this weight
to the weight at the tongue that is attained with a scale and you have
your gross trailer weight. Knowing the total weight and the tongue
weigh allows you to calculate the percentage of weight on the hitch.
While you're there the first time, it would be a good idea to also check
the vehicle weight at each axle to make sure it is not loaded beyond the
manufacturer's specifications. (See the Trailer/Tow Vehicle Load
Worksheet for more details.)
YOUR RESPONSIBILITIES AS A DRIVER
Towing a trailer
has a responsibility similar to properly driving your
car. You wouldn't think of letting your children drive on the road without
the proper training, and you shouldn't take a fully loaded trailer that
could be improperly loaded onto a busy road to learn with. It is a
skill that has to be developed and a responsibility that shouldn't be
taken lightly. If you're towing a travel trailer for the first time,
you have to start learning with a full load. Drive only when traffic
is light and don't drive where traffic conditions might force you into
driving faster than you are comfortable with. Get a friend with this
type of experience to help you learn. Don't be embarrassed to ask
questions or park when it is windy. Learn what it takes to keep from
ruining your transmission when pulling heavy loads up a hill or burning
your brakes up going down the other side. It is a skill that you can
take pride in. The hardest skill to learn is to know when not to tow
a trailer.
Travel trailers,
boat trailers, and specialty trailers are usually
designed to have the proper hitch weight, but it would be intelligent to
check them. Make sure your hitch is capable of handling the load.
You can still screw up the design by putting something heavy where it was
never intended to go such as a heavy outboard on the back of a sailboat.
Another way of getting in trouble with a boat is towing it when it has a
lot of water in the bilge from a rainstorm. If you add heavy items
to this type of trailer, put the extra weight over the axles. If
you're putting a boat on a trailer for the first time, use a scale to find
the proper place to locate the boat and adjust the trailer to fit the
boat.
DRIVING IN WINDY CONDITIONS

Wind can create
havoc when towing a trailer, causing oscillations or
sudden pulling to one side. Thirty mile an hour crosswinds can blow
you off the road if there is a sudden gust. For example, say a hard
gust of wind hits your rig from the left. Your rig pitches to
the right and moves towards right. In order to stay on the road you
turn left. With the rig leaning to the right, the centrifugal force
generated by the left turn can be the added ingredient that puts you on
your side, or worse yet, down the side of a ravine. The only way to
help lower the risk traveling in these conditions is to slow down.
This eliminates the centrifugal force that happens when you correct, and
if the wind did blow you over it wouldn't be such a violent crash.
The safest way is not to drive in extremely windy conditions. That's what
the professional haulers do, and so should you. Park it until it's
safe to continue. Wind can also have a dramatic effect on your fuel
mileage when towing a heavy load. Plan your fuel stops accordingly.
NOTE: Several types of trailer sway control braces are available that
can minimize the effects of wind gusts and passing trucks.
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WIND FROM PASSING TRUCKS
An interesting
thing happens when being passed by faster moving buses
or large trucks. Large vehicles develop a high pressure wave of air
in front of them and low pressure area to their rear as they go down the
highway. This is variable and is dependent on the shape of the truck
and the existing wind conditions. The effect is such that as the
truck comes up to pass on your left, first your trailer and then your tow
vehicle will be pushed to your right by the truck's "bow wave". As the
truck passes, the low pressure zone will then pull you back to the left.
You must steer first left and then right to counter the effect. It's
not particularly dangerous, but it does keep you on your toes.
MORE TOWING TIPS

HANDLING TRAILER SWAY...
If swaying occurs,
steer as little as possible while you slow down.
Because of your natural lag in reaction time, quick steering movements
will actually make things worse and cause the oscillation to increase.
Application of the trailer brake usually tends to help keep the vehicles
aligned, while heavy braking with the tow vehicle may reduce trailer
stability. Until the problem is identified and solved, travel at
reduced speeds.

Heavy items
loaded to one side of the trailer can cause
oscillation or handling problems in turns.
NOTE ABOUT LOAD EQUALIZING HITCHES...
A load equalizing
hitch is selected base on the trailer's actual tongue
weight rather than on gross weight. This type of hitch has some real
advantages, but government studies have shown they can actually work too
well, lightening the load on the rear wheels of the tow vehicle and reduce
traction. This kind of hitch should be selected carefully, installed
by professionals and its operation understood by the user.
This type of hitch is HIGHLY recommended.
WATCH YOUR TRAILER'S WHEELS IN TURNS...

The longer the trailer, the
wider you must swing in a turn to make sure the trailer wheels clear the inside curb.
SOMETHING TO THINK ABOUT...
A temporary
increase in loading occurs during dips or bumps in the
road. A severe dip causes increased weight to suddenly be placed on
hitch, axles and tires. Though hitch manufacturers take this into
consideration in their designs, an overloaded or old, cracked and rusted
hitch or tongue can be suddenly stressed beyond capacity, causing it to
fail. Watch for bumps and large dips in the road and try to slow
down for them. A conservative safety margin in loading will also be
helpful in this type of unforeseen circumstance.

NOTE: Whenever
the trailer is detached from the tow
vehicle, block the wheels so it is impossible for the trailer to roll off
on its own. Better yet, don't ever detach the trailer on any grade.
Safe Towing Checklist
-
Check for proper ball and coupler sizing
-
Coupler is locked and secured with safety clip
-
Inspect safety chains
-
Inspect brake wiring and harness, clean if necessary
-
Inspect and/or clean lighting plug and receptacle
-
Inspect all hitch components for cracking or broken welds
-
Test breakaway switch
-
Check tire pressures, inspect each for wear
-
Check wheel nut torque
-
Check exterior lighting, brake lights and turn signals
-
Lubricate coupler and latch
-
Tongue Jack is raised fully
-
Dolly wheel removed (if appropriate)
-
Trailer is about level
-
Cargo is secured and tied down
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