image above to see all Tekonsha controllers with wiring
harnesses for various truck models.
(Opens in a new window)
When you are pulling upwards of 10,000 lbs, you want
to make sure you can stop quickly and effectively.
If a truck is not fitted with a factory trailer brake
controller then the Tekonsha P3 trailer brake controller
uses a G-Sensor accelerometer, instead of the traditional
pendulum mechanism. This brake controller is one of
the best available and works reliably on downhills
and inclines, unlike the current pendulum brake controllers.
This brake controller will stop the trailer with almost
no shuddering and the troubleshooting feature allows
you to view diagnostics which is extremely helpful.
The Tekonsha also shows an alert should the trailer
brakes come disconnected for some reason. Tekonsha
provides a wiring harness for almost any model of
truck. This makes installation easy compared to trying
to wire in other makes of brake controllers.Tekonsha
has been a best seller for a while now and with good
What is Gross Axle Weight
Rating (GAWR) and do we care?
The Gross Axle Weight Rating is the maximum weight
the axle can carry. Here is where it gets confusing.
This means all of the weight the axle can carry, including
the weight of the axle itself and the truck bed. For
us to know how much we can load onto the truck, like
the weight of the front of the Fifth Wheel, we ignore
this rating as we don't know how much the axle and
truck bed weigh.
The way we calculate how much weight the truck can
be loaded with is to check the Maximum Payload capacity
for that truck. If we cannot find that then we can
calculate it like this:
How to Calculate Truck Payload
Take the Gross Vehicle Weight Rating (GVWR) and subtract
the Curb Weight of the truck. Both of these weights
should always be in the specifications for the truck.
So if we have a GVWR - the total weight the truck
can be loaded with of say 9900 lbs and a curb weight
of 6469 lbs then: 9900 minus 6469 = a max payload
of 3431 lbs.
So from our calculation above we can load a Fifth
Wheel that has a front pin weight or hitch weight
of 3000 lbs with no problem right? Wrong. We have
to take into consideration the weight of the passengers
in the truck, the extra weight of a full fuel tank
and any other cargo loaded into the truck.
So when selecting a truck we need to know the Hitch
Weight or Pin Weight of the Fifth Wheel we will be
pulling. That weight is normally always in the specifications
for the Fifth Wheel.
When we see these huge Fifth Wheels, one tends to
think that the front end weight or hitch weight of
the Fifth Wheel must be huge. But most Fifth Wheels
hitch weights average around 2,000 lbs or less. The
40 foot Big Horn weighs an impressive 16,000 lbs but
the hitch weight is only 2,040 lbs.
Above we just calculated how much we can load into
the truck, which includes one of our most important
weights. The weight of the front of the Fifth Wheel.
This is the weight that will be pushing down on the
rear axle when the Fifth Wheel is hitched to the truck.
How Truck Tires can Increase
tires have a load rating specification.
If the standard tires on the truck are rated for 3,000
lbs and you replace those tires with a tire rated
for 3,400 lbs, then you have just increased the payload
capacity by 800 lbs.
How Much Weight Can The Truck
Now we need to know how much the truck can pull behind
it and this weight will be the maximum weight of our
Fifth Wheel RV or we will exceed the towing capacity
of the truck. If we exceed the towing capacity of
the truck we will put excess strain on the engine,
the transmission and the brakes. The truck will not
perform well pulling the Fifth Wheel and steep inclines
could overheat the engine. Driving an overloaded truck
is stressful and if an accident were to occur, insurance
could be affected by the fact the truck was overloaded.
If we look at a Fifth Wheel RV we see in the specifications
that there is a Dry Weight, a Gross Weight and a Cargo
So for example a 40 foot Big Horn 3755 FL has a Dry
Weight of 13,910 lbs and a Gross Weight of 16,000
So we need a truck with a maximum tow capacity of
16,000 lbs and a 16,000 lb hitch right? Not so. We
need to factor in added weight from the fresh water
tank and cargo we have stored in the Fifth Wheel.
Let's look at the 3755FL Big Horn again. It can carry
73 Gallons fresh water, 90 gallons grey water &
45 gallons black water. That is an extra 1,734 lbs
just in water.
It is far better to have an over rated truck than
one that's max. towing capacity is very close to the
gross weight of the Fifth Wheel RV. If this is the
case then the truck will almost always be over loaded.
We also want to make sure that the hitch for the Fifth
Wheel is rated more than the Gross Weight of the Fifth
Wheel. This would be our safety zone.
When you look at truck specifications you will see
Conventional Trailering and Fifth Wheel Trailering.
Conventional Trailering is tow capacity with a ball
hitch on the rear of the truck. We want to look at
Fifth Wheel Trailering for our weights.
Bringing it all Together
- Gross Combined Weight Rating (GCWR)
When the Fifth Wheel is hitched to the truck and the
Fifth Wheel is loaded for travel, along with the truck
with its driver and passengers and fuel, the weight
of the loaded truck and the loaded Fifth Wheel should
not exceed the Gross Combined Weight Rating shown
in the specifications for the truck.
the comparison chart at the bottom of this page we
can see that a 2 wheel drive crew cab long box with
a Duramax 6.6L Diesel-Turbo V8 engine and a 3.73 rear
axle has a GCWR of 24,500 lbs. We can see that the
maximum for the loaded truck is 10,000 lbs (that is
the weight of the truck and its payload capacity).
We then calculate 24,500 lbs minus 10,000 lbs and
arrive at 14,500 lbs. If we build in approx. 2000
lbs of cargo in a fifth wheel (that includes the water
tanks and cargo bay contents) then we arrive at 12,500
lbs as the maximum Fifth Wheel weight that we can
safely tow with that vehicle.
Factors that affect Towing
The comparison chart below allows you to select the
various models of trucks, Regular Cab Long Box, Crew
Cab Standard Box, Crew Cab Long Box etc.
You can also select the various engine options and
4 wheel drive or 2 wheel drive models.
By selecting these various options you will see how
these options either decrease or increase the towing
capacity for a Fifth Wheel. The comparisons below
represent the same increase or decrease reasons for
nearly all models or makes of trucks.
One would need to take these towing capacity adjustments
into consideration when buying a truck. For instance
look at how a 4x4 trucks towing capacity is affected
compared to a 2 wheel drive truck, and how an axle
ratio of 3:73 affects capacity compared to an axle
ratio of 4:10. Also look at how a diesel engine compares
to a gas engine for towing.
If you need to find Tow Ratings for a vehicle, here
is a comprehensive Tow Guide. The Tow Ratings start
on page 18. 2014
Tow Guide (Will open in a new