The Hummer H3 isn't a bespoke model like the original Army H1 or the H2 civilian version of the H1; it's actually a re-body of the Chevrolet Colorado and GMC Canyon. Without a trailer, the safest way to tow an H3 is to remove the front and rear drive shafts. Leaving them in place can result in severe transfer case damage, which is why many drivers opt to trailer their Hummers instead of to flat-tow or use a car dolly.
Acquire a flat-bed car trailer with a 2-inch ball hitch and a bed measuring at least 16 feet long by 6.5 feet wide with at least 5,000 lbs. of cargo capacity. You could use a 10-foot-long trailer to accommodate the Hummer's 9-foot, 3-inch wheelbase, but expect the front and rear of the truck to hang over the ends of the trailer. A trailer that can carry 5,500 lbs. would be a safer option than a 5,000-lb. trailer; the H3 only weighs 4,900 lbs., but that's without accounting for a full tank of fuel and anything else that might be aboard.
Connect the trailer to your tow vehicle and lower its landing legs if so-equipped. Connect the trailer's safety chains and electrical harness connector to your tow vehicle and lower the loading ramps. Adjust the ramps so that they line up with the H3's front wheels. Do not allow the ramps to exceed the H3's maximum rear approach angle of 35.5 degrees. In the real world, this works out to about 3.5 feet of ramp length for every 1 foot of trailer height.
Start your H3 and put it into four wheel drive. Slowly drive it up the loading ramps while an assistant directs you. The H3 has a 65.5-inch front track width, so subtract that from your trailer width and divide by two to determine how close you need to stay to the driver's side of the trailer bed while loading. Drive the H3 up onto the trailer until the trailer axle falls just below your front door handles.
Loop your tow straps over top of the frame rails just behind the front and rear bumpers, and then connect the strap hooks to the hook eyes on your trailer. Pull the straps hand-tight and then begin ratcheting them down. There's a technique to this; ratchet each strap down by three to four clicks, then move on to the next one in a clockwise direction. Continue working your way around the truck until the wheel arches are about 2 inches closer to the wheels than they were when you started. Securing the truck in this way will pre-load the suspension, which helps to prevent unnecessary trailer roll and possible disaster.
