Chevrolet 2009 Suburban Owner's Manual page 384

If the vehicle has many options and there is a front
seat passenger and two rear seat passengers with some
luggage and gear in the vehicle as well. 300 lbs (136 kg)
could be added to the front axle weight and 400 lbs
(181 kg) to the rear axle weight. The vehicle now weighs:
Weight is still below 7,200 lbs (3 266 kg) and you
might think 700 additional pounds (318 kg) should be
subtracted from the trailering capacity to stay within
GCWR limits. The maximum trailer would only be
7,800 lbs (3 538 kg). You may go further and think the
tongue weight should be limited to less than 1,000 lbs
(454 kg) to avoid exceeding GVWR. But the effect on the
rear axle must still be considered. Because the rear axle
now weighs 3,100 lbs (1 406 kg), 900 lbs (408 kg) can
be put 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 only
600 lbs (272 kg) of tongue weight that can be handled.
4-56
Since tongue weight is usually at least 10 percent of total
loaded trailer weight, expect that the largest trailer the
vehicle can properly handle is 6,000 lbs (2 721 kg).
It is important that the vehicle does not exceed any of
its ratings — GCWR, GVWR, RGAWR, Maximum Trailer
Rating or Tongue Weight. The only way to be sure it
is not exceeding any of these ratings is to weigh
the vehicle and trailer.
Total Weight on the Vehicle's Tires
Be sure the vehicle's tires are inflated to the upper
limit for cold tires. These numbers can be found on the
Certification label at the rear edge of the driver's door or
see Loading Your Vehicle for more information. Make
sure not to go over the GVW limit for the vehicle, or the
GAWR, including the weight of the trailer tongue. If using
a weight distributing hitch, make sure not to go over the
rear axle limit before applying the weight distribution
spring bars.
Hitches
It is important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads
are a few reasons why the right hitch is needed.