Originally Posted by mongox
Ramp up onto the trailer, then ramp from the trailer to the bed.
I always either push it up if I have to, or walk alongside in first gear if possible. I've only had one incident, I was unloading from a trailer and using some HF ramps. The ramp was upside down so the flanges would act as a guide and hopefully keep the wheels from rolling or sliding off. Only they didn't. Just about when both wheels were on the ramp I let go of the brake to let gravity do it's thing, and halfway down the front wheel rolled over the lip and off the ramp. Not so much of a big deal, it was about a foot off the ground and I kept the bike upright, but the ramp was taco'd.
I've backed the truck up to a ditch (a good ditch and the tailgate will be just about level) and rolled them in and out, I've pulled the tailgate off and used it for a ramp. (prepare for paint damage) When I bought my Buell the guy had it loaded in the back of his truck, then I backed mine up to his and we rolled from one to the other.
Ir you could find a hill and a ramp.