Originally posted by Graystroke
I think it's better to strap the vehicle down and compress the suspension(from the bumpers/tow points). There's something to be said when every known vehicle manufacturer does it this way when they transport. Also you don't want the load shifting. I also read somewhere from a race car tech that they strap to the body to keep the suspension from cycling and nicking the races in the wheel bearings, which makes since. If you think about it all that weight of the truck goes up and down on the same part of the bearing w/ out rotating like it would if you were going down the road.
If I haul a vehicle I use four straps criss crossed front and rear w/ a safety chain in the front to the trailer just in case. It maybe overkill, but I never have had any problems and can go down the road w/ a little peace of mind.
to add some fun info about the bearings grayson was talking about. I am not sure what motor company did this but anyway. They were transporting cars in the 40's to CA on railcars. And when the cars got there they were fine but they noticed the wheel bearings were wearing out in 10000 miles and they had no idea why this was happening. So they found out it was due to the railcar cause it was a rough ride and the bearings rubbed in one spot and messed them up. So yes keep your car from moving on the trailer.

one more fun bearing story
A company had some bearings in thier shop. They also had some big machines running making vibrations. They had there bearings stored on edge and they failed when they were in use way before they were supposed to fail. The vibrations from the machines in the next room cause them to rub and in one tiny spot mess them up. So if you are going to store bearings lay them down flat and pack them with grease this will help. By laying them down flat the bearing has more contact area than it sitting on edge. and grease can never hurt.