2003 GMC Envoy Owner's Manual - Page 286

If You Do Decide To Pull A Trailer If you do, here are some important points: There are many different laws, including speed limit restrictions, having to do with trailering. Make sure your rig will be legal, not only where you live but also where you'll be driving. A good source for this information can be state or provincial police. 0 With an automatic transmission, you can tow in DRIVE (D). You may want to shift the transmission to THIRD (3) or, if necessary, a lower gear selection if the transmission shifts too often e.g., under heavy loads and/or hilly conditions. Three important considerations have to do with weight: the weight of the trailer, 0 Consider using a sway control if your trailer will weigh 4,000 Ibs. (1 816 kg) or less. You should always use a sway control if your trailer will weigh more than 4,000 Ibs. (1 816 kg). You can ask a hitch dealer about sway controls. Don't tow a trailer at all during the first 500 miles (800 km) your new vehicle is driven. Your engine, axle or other parts could be damaged. Then, during the first 500 miles (800 km) that you tow a trailer, don't drive over 50 mph (80 km/h) and don't make starts at full throttle. This helps your engine and other parts of your vehicle wear in at the heavier loads. the weight of the trailer tongue and the weight on your vehicle's tires. 0 4-53