A 4x4 loading into either a full size or smaller truck can traverse the

loading ramp at a slow speed because, with both front and back wheels driving, traction is not a problem. It helps to have a small ramp to assist one front wheel get over the rear wheel well in a mid-size or smaller truck. This is because on the smaller trucks, the distance between the rear wheel wells is less than the width of a full size ATV and you must ride up and over one wheel well to get in the truck far enough to close the tailgate on a 7ft. box. With a 6ft. box the ATV's rear tires will remain on the tailgate.
With a 2x4 machine, especially at steeper ramp angles, speed (momentum) is more important than traction, especially if you have to ride up and over a wheel well. It will take practice to ride a 2x4 ATV up a steep angled loading ramp at +10mph and hop over a wheel well and come to a stop before hitting the rear of the bed. (See warning below) It is best to cut throttle as you start up the wheel well (or the helper ramp) and apply the front brakes as you reach the top and then slide down on the other side of the wheel well into position.
WARNING
Danger of serious personal injury exists. Serious personal injury can occur when loading a 2x4 ATV as described above. The above procedure is for expert riders only.
One final note after loading; remember to turn the key off and remove it, turn the fuel off and set the parking brake. For manual clutch machines, leave the machine in gear. Fold up your ramp and slide it under the ATV securing it from sliding out if you have to leave the tailgate down.