GMC 2007 Envoy - Manual (Page 367)

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).
But let’s say your specific vehicle is equipped with
some of the latest options and you have a front
seat passenger and two rear seat passengers with
some luggage and gear in the vehicle as well.
You may add 300 lbs (136 kg) to the front axle
weight and 400 lbs (181 kg) to the rear axle
weight. Your vehicle now weighs:
Weight is still below 7,200 lbs (3 266 kg) and you
may think that you should subtract 700 additional
pounds (318 kg) from your trailering capacity
to stay within GCWR limits. Your maximum trailer
would only be 7,800 lbs (3 538 kg). You may go
further and think you must limit tongue weight
to less than 1,000 lbs (454 kg) to avoid exceeding
GVWR. But, you must still consider the effect
on the rear axle. Because your rear axle now
weighs 3,100 lbs (1 406 kg), you can only
put 900 lbs (408 kg) on the rear axle without
exceeding RGAWR. The effect of tongue weight is
about 1.5 times the actual weight. Dividing the
900 lbs (408 kg) by 1.5 leaves you with being able
to handle only 600 lbs (272 kg) of tongue weight.
Since tongue weight is usually at least 10 percent
of total loaded trailer weight, you can expect
that the largest trailer your vehicle can properly
handle is 6,000 lbs (2 721 kg).
It is important that you make sure your vehicle
does not exceed any of its ratings — GCWR,
GVWR, RGAWR, Maximum Trailer Rating
or Tongue Weight. The only way to be sure you
are not exceeding any of these ratings is to weigh
your vehicle and trailer.
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