GMC 2007 Yukon XL Owner's Manual page 412

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 have loaded the trailer, weigh the trailer
and then the tongue separately, to see if the
weights are proper. If they are not, you may be
able to get them right 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.
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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).