GMC 2005 Savana Van Owner's Manual page 232

Total Weight on Your Vehicle's Tires
Be sure your vehicle's tires are inflated to the upper
limit for cold tires. You'll find these numbers on
the Certification label at the rear edge of the driver's
door or see Loading Your Vehicle on page 4-31.
Then be sure you don't go over the GVW limit for your
vehicle, or the GAWR, including the weight of the
trailer tongue. If you use a weight distributing hitch,
make sure you don't go over the rear axle limit before
you apply the weight distribution spring bars.
Hitches
It's important to have the correct hitch equipment.
Crosswinds, large trucks going by and rough roads are
a few reasons why you'll need the right hitch.
4-44
Weight-Distributing Hitches and Weight
Carrying Hitches
(A) Body to Ground Distance, (B) Front of Vehicle
When using a weight-distributing hitch, the hitch must
be adjusted so that the distance (A) remains the
same both before and after coupling the trailer to the
tow vehicle.