2009 Hummer H3T Owner's Manual - Page 227

Driving Your Vehicle Weight of the Trailer Tongue The tongue load (A) of any trailer is an important weight to measure because it affects the total gross weight of the vehicle. The Gross Vehicle Weight (GVW) includes the curb weight of the vehicle, any cargo carried in it, and the people who will be riding in the vehicle.If there are a lot of options, equipment, passengers or cargo in the vehicle, it will reduce the tongue weight the vehicle can carry, which will also reduce the trailer weight the vehicle can tow. If towing a trailer, the tongue load must be added to the GVW because the vehicle will be carrying that weight, too. See Loading the Vehicle on page 4-35 for more information about the vehicle's maximum load capacity. 4-45 If the spare tire carrier is mounted on the back of the vehicle and the hitch extension is too short, the spare tire may interfere with trailer coupling or trailer tongue jack operation on some types of trailers. After loading the trailer, weigh the trailer and then the tongue, separately, to see if the weights are proper. If they aren't, adjustments might be made by moving some items around in the trailer. 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 the 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.