Chevrolet 2005 Astro Owner's Manual page 205

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/Tire label at the rear edge of the driver's
door or see Loading Your Vehicle on page 4-28. Then
be sure you don't go over the GVW limit for your vehicle,
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.
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.
4-39