Chevrolet 2006 Express Van, Owner'S Manual, Page: 247 / 404

Do not exceed the maximum allowable tongue weight
for your vehicle. Choose the shortest hitch extension
that will position the hitch ball closest to the vehicle. This
will help reduce the effect of trailer tongue weight on
the rear axle.
After you’ve loaded your trailer, weigh the trailer and
then the tongue, separately, to see if the weights are
proper. If they aren’t, you may be able to get them right
simply by moving some items around in the trailer.
Trailering may be limited by the vehicle’s ability to carry
tongue weight. Tongue weight cannot cause the vehicle
to exceed the GVWR (Gross Vehicle Weight Rating)
or the RGAWR (Rear Gross Axle Weight Rating).
The effect of additional weight may reduce your trailering
capacity more than the total of the additional weight.
Consider the following example:
A vehicle model base weight is 5,500 lbs (2 495 kg);
2,800 lbs (1 270 kg) at the front axle and 2,700 lbs
(1 225 kg) at the rear axle. It has a GVWR of 7,200 lbs
(3 266 kg), a RGAWR of 4,000 lbs (1 814 kg) and a
GCWR (Gross Combination Weight Rating) of
14,000 lbs (6 350 kg). The trailer rating should be:
You can expect tongue weight to be at least 10 percent
of trailer weight (850 lbs (386 kg)) and because the
weight is applied well behind the rear axle, the effect on
the rear axle will be greater than just the weight itself,
as much as 1.5 times as much. The weight at the
rear axle could be 850 lbs (386 kg) X 1.5 = 1,275 lbs
(578 kg). Since the rear axle already weighs 2,700 lbs
(1 225 kg), adding 1,275 lbs (578 kg) brings the total
to 3,975 lbs (1 803 kg). This is very close to, but within
the limit for RGAWR as well. The vehicle is set to
trailer up to 8,500 lbs (3 856 kg).
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