Hummer 2007 H3 - Manual (Page 300)

The trailer tongue weight (A) should be 10 percent
to 15 percent of the total loaded trailer weight (B),
up to a maximum of 500 lbs (227 kg) with a weight
carrying hitch or a weight distributing hitch.
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.
Your spare tire carrier is behind the tailgate.
If your hitch extension is too short, the spare
tire may interfere with trailer coupling or trailer
tongue jack operation on some types of trailers.
After you’ve loaded your trailer, weigh the
trailer and then the tongue, separately, to see if
the weights are proper. If they aren’t, you may be
able to get them right simply by moving some
items around in the trailer.
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 located on the
B-pillar below the door latch or see Loading Your
Vehicle on page 289. 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.
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