Buick 2007 Terraza Owner's Manual page 389

If you are using a weight-carrying or a
weight-distributing hitch, the trailer tongue
weight (A) should be 10 percent to 15 percent of
the total loaded trailer weight (B). Do not exceed
the maximum allowable tongue weight of 350 lbs
(159 kg) for your vehicle.
After you have loaded your 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 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.
389