John,
My apologies for not being very clear. I thought you were joking because I displayed it on the trailer wheel instead of a loaded tractor. Obviously this wouldn't secure your load well and make driving quite difficult /forums/images/graemlins/smirk.gif
The way the strap is on the tire of the trailer is basically the way it is used. It's one strap, made of several pieces.
To use it, put your tractor on the trailer, then put one of these over each of the front wheels. The straps you see on the left and right of the trailer wheel and laying on the ground are ratcheted and used to tie directly to the bed of the trailer, tying the wheels/tires down.
The horizontal strap tightens around the tire to hold it secure and adjust for different size tires.
This strap holds the vehicle down against the trailer and prevents it from moving forward/backward or left/right. And since it attaches to the wheel and the vehicle is made to be stable about and controlled by the wheels (main point of support), the entire vehicle is well supported and tolerates the trip very well.
Think of it like this. If you could put each of your front wheels in a 12" deep recessed hole that was exactly the width of your tires and strapped them into the hole, think how well would it hold your tractor on the trailer. Essentially, that's what these straps do, except instead of a hole under the tire, it wraps around the top, allowing significant tie down pressure to be applied.
These purpose made straps are considered about the best way to secure a vehicle. Combine them with regular binders or straps over the rear axles, and your tractor is very well secured.
-JC