When Optimus Prime transforms into a robot where does the 5th wheel on the big rig go?

Question

for those of you that don't know, the 5th wheel is the horseshoe looking thing on the back of the truck that hooks onto the trailer.

Answer 1

Well I think thats why in the movie, Optimus was only a truck and not one big 18-wheeler so it would make more sense.

The action figure was made to where Optimus transformes from the truck and the other part becomes some sort of weapon for the autobots.

Yea its kinda wierd but ok then!

Answer 2

It splits down the middle, and is located on the back of his knees.

Answer 3

It becomes part of his legs.

I think the better question throughout the years is where does his trailer go?