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 Dear
Andy:
After reading your article "A Question Of Torque"
(Vol. 32 No.3), I am now really confused about tow
vehicles. I bought my 24 foot Trail Bay trailer (dry
weight of 4,350 pounds) while driving a 1998 Ford
Explorer (AWD). It was tow rated at 6,500 pounds,
but even with a class four hitch & equalizer bars
I could not exceed 55 kilometers per hour without
the trailer causing the Explorer to sway violently
from side to side. I had an anti-sway bar installed
which allowed the speed to increase to 90 km/hour,
but any car or truck coming up behind instantly caused
the back end of the Explorer to sway. It became downright
scary when they passed.
After a test drive, I traded the Explorer in for
a 1998 Chevy Tahoe 4x4, which is tow rated at 6,600
pounds. Both vehicles had a similar two rating, had
four wheel drive capability, sufficient engine power
& less than 50,000 kilometers mileage. It was like
day & night between the vehicles. The Tahoe performs
like what I expected of a tow vehicle.
You covered torque in your article, but what is
the Intrepid rated at for towing? I'm surprised it
exceeds a minivan and, apparently, my Tahoe since
you pulled a 7,000 pound trailer with it. Could you
have legally pulled that trailer with the Intrepid
in British Columbia, where they are so strict?
We are looking at trading in our current trailer
for a slightly larger one (29 feet, nine inches in
length, including hitch) with a slide-out. I estimate
it will weigh approximately 7,300 to 7,500 pounds
by the time I get it loaded. It means trading the
Tahoe in for something else and I've considered a
3/4 ton van. Although a sedan (or a pickup) is not
convenient for our circumstances, are you suggesting
the Intrepid theoretically would do the job?
What am I missing in this subject?
Thanks,
Paul Cordingley
Calgary, Alberta
Hi Paul,
From a power perspective you will be able to tow
the larger trailer with your Tahoe. There may be the
odd hill that you now climb in third gear that you
will need second but other than that, there won't
be a substantial difference in performance. Handling
is another issue however.
The poor handling you experienced with the Explorer
was due to the large, soft sidewall tires that are
so popular on SUVs and trucks these days. You likely
should have had two sway bars and though you had all
the pieces of a hitch, it was not likely even close
to being adjusted properly. It is also quite possible
that the hitch receiver was too weak for the torsion
bars, so it may have been impossible to set the hitch
properly. You do illustrate the point though, that
there is more to choosing and setting up a tow vehicle/trailer
combination than just making sure the trailer weight
falls within the manufactures towing recommendation.
In this complicated world I think we all want to find
ways to simplify things. Weight is an easy criteria
to measure, so we would like to think that all there
is to towing is to find a trailer that weighs less
than the vehicle manufacturer's maximum recommendation.
However, there are shortcomings with simply going
with the manufactures towing recommendations. Here
are a couple:
1) Weight is the only referenced criteria, as though
nothing else matters. Weight is a factor when towing,
of course, but only one of many and it's not a major
one. For example, you could load 2,000 pounds of extra
weight in your present trailer and be hard pressed
to tell the difference. You may notice a slight increase
in the effort to pull it away from a stop. It would
be slightly more stable in straight-line handling
on the highway and slightly less stable during an
emergency manoeuvre. If you increased the size of
the brakes on the trailer to match the weight, then
stopping would be about the same. However take out
the extra weight and extend the spring hangers so
the trailer sits six inches higher off the ground
and you will notice a substantial difference in towing.
It would be more difficult to pull through the air
at highway speed and the handling would deteriorate
substantially. Both straight-line stability and emergency
manoeuvre handling would be challenging.
2) There is no standardized test for establishing
a tow rating. For example, automotive crash or brake
tests have a detailed set of requirements and measurements
that are used to make it valid and consistent. No
such criteria exist for establishing a tow rating
and again how would you establish it? Since a good
handling 7,000 pound trailer tows better than a poor
handling 4,000 pound one, would you use the towing
characteristics of the best towing or worsttowing
trailer to establish the rating? Would you establish
the rating for someone that is going to drive 110
Kph, or someone that is happy at 90 Kph? Would you
set up the conventional equalizing hitch properly,
or would it need adjustment (as most do)? Would you
use a Hensley or a Pull-Rite? Obviously the rating
system would have to reference much more than weight
alone. It would have to be performance based, not
based on numbers plucked out of the air.
I don't mean to criticize the vehicle manufactures,
as they are in a very difficult position. They build
a vehicle, try to establish a towing recommendation
and then it is out of their hands. There are millions
of combinations of trailers and hitches that could
be connected to it and they have absolutely no control
of what happens after it leaves the factory. I have
often said É knowing what I know about the towing
characteristics of some trailers, the inadequacy of
some brake controls and how poorly most hitches are
set up É if I was a vehicle manufacturer I would rate
everything at zero! I would not want anything to do
with towing. If it is any consolation though, RVs
are generally set up much better than boat or horse
trailers.
Regarding the legalities, from what I understand
the main problem in BC was some people were grossly
overloading axle capacities. For example putting a
3,000 pound truck camper on a half ton truck, then
hooking up a 5,000 pound boat with very little or
no brake capacity. I have travelled through BC and
I have many customers that travel there with trailers
well over the towing recommendation, but they are
not grossly overloading axle or tire capacities or
in any way driving an unsafe combination. It would
be very difficult to legally reference a towing recommendation
that has no recognized test criteria.
Of course there are many ways to look at safety.
If you drive a one ton truck you are likely to fare
better when you hit a lighter vehicle, but I would
rather travel with my family in something that stops
in as short a distance as possible and manoeuvres
quickly so I can avoid the collision in the first
place.
Now the main question is, "can you safely tow
a 29 foot slide-out trailer with your Tahoe?"
The answer is yes, if you do everything right, and
no if you do not.
Large slide-outs have to clear the top of the tires
to operate which means that the trailer has to be
much higher off the ground. This makes the walls higher
and of course they are going to be longer so they
catch more cross winds and are more affected by passing
trucks and other large vehicles. Also, the centre
of gravity becomes much higher.
When you are selecting the trailer look for five
things:
1) As low a floor as possible.
2) As streamlined a design as possible.
3) Measure the hitch weight yourself as sometimes
the brochures can be wrong. It should be 700 to 900
pounds. You can do this with a bathroom scale and
some pipes and a 4x4, or you can purchase a small
easy-to-use tongue scale or the dealer may have one
you can use.
4) 12 inch brakes with six lug wheels.
5) Shock absorbers.
If you find a trailer that is 1,000 pounds heavier,
but the floor height and overall height is four inches
shorter and the front end is streamlined, it will
be a better choice from a towing perspective.
On the Tahoe there are some changes to make.
1) Change the tires to 225/75R x 16" LT (light truck)
load range D. These tires will have a fraction of
the side sway compared with your present tires, and
being slightly smaller will give you more power to
help with the additional wind resistance. These tires
are rated for 65 PSI, but 45 will be what you will
want to carry in them for towing.
2) If you do not have the factory transmission cooler,
install one and make sure you are using the factory
spec synthetic fluid.
3) Change your brake control to one that is positive
acting off of the movement of the brake pedal. The
test of a brake control is that if you are moving
or sitting still and you press hard on the brake pedal
the trailer brakes should be on full without any time
delay.
4) If you look at your hitch receiver you'll find
it is very solidly made (and much better than most
new ones). Unfortunately, it fastens on a very short
section of the frame of the Tahoe. It would be good
to lengthen this fastening further up the frame to
take the flex out of the hitch attachment. A good
hitch installer with welding capability should be
able to do this pretty easily.
5) Get a Hensley or Pull-Rite hitch. They are by
far the best way to tow a large slide-out trailer.
A Hensley is about $4,000 - it seems expensive but
it is a bargain compared to the cost of trading vehicles.
Done properly you will have a better towing, safer
combination than you have now. In fact, it will feel
so good you will be tempted to drive faster but 100
Kph is fast enough for many RVs and any time you save
will be spent in gas stations anyway. Enjoy your new
trailer and send me any further questions.
Thanks for writing.
Andy (Page Top)
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