2006 Buick Rainier Owner's Manual - Page 307

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. 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. The trailer tongue weight (A) should be 10 percent to 15 percent of the total loaded trailer weight, up to a maximum or 400 lbs (181 kg) with a weight carrying hitch. The trailer tongue weight (A) should be 10 to 15 percent of the total loaded trailer weight, up to a maximum of 750 lbs (340 kg) with a weight distributing hitch. 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. 4-55