Trailer swing while backing and position of tandems?

When I attended CR England's trucking school in 2012, the paperwork that CR England gave me listed the advantages and disadvantages of having the tandems slid all the way forward, and the paperwork listed the advantages and disadvantages of having the tandems slid all the way back.

As I recall, the paperwork said that if the tandems are all the way to the rear when you are backing, you have to turn the steering wheel farther to get the trailer to react than if the tandems are all the way forward. Is that correct?

Anyway, I understand how the position of the tandems would affect how far you have to turn the steering wheel when you are backing. However, if I recall correctly, paperwork CR England gave me said that if the tandems are all the way forward when one is driving forward and turning the steering wheel (e.g. pulling forward out of a parking spot at a trucking stop), the rear of the trailer would move to the opposite direction that one is turning. For instance, the paperwork said that if a semi-truck driving forward out of a parking spot and the steering wheel is turned to the left (so the tractor moves to the left), then the rear of the trailer would go to the right. But the paperwork said that if a semi-truck has the tandems all the way to the rear, and the semi-truck drives forward out of a parking spot and the steering wheel is turned to the left, then the rear of the trailer won't move to the right with the tandems slid all the way to the rear. I agree with CR England that if a semi-truck drives forward out of a parking spot and the steering wheel is turned to the left, then the rear of the trailer won't turn to the right if the tandems are slid all the way back. But I don't think that the rear of the trailer would turn to the right if the semi-truck pulled forward and the steering wheel was turned to the left with the tandems all the way forward.

If the tandems are slid all the way forward on a semi-trucking driving forward out of a parking spot, and the steering wheel is turned to the left, will the rear of the trailer move to the right?

If the rear of the trailer did move to the right, what would cause the rear of the trailer to move to the right? The tandems don't pivot like the tractor-trailer pivots at the kingpin.

 

I totally understand that if I balance a pen on my finger, and if I push the pin down, the other end of the pin will go up. If I balance a pen on my finger, my finger is a pivot point. But when I am pulling a semi-truck forward out of a parking spot and turning the steering wheel to the left, the pivot point is the kingpin of the trailer, not the tandems. I don't understand why the position of the tandems would make a difference.

Please give me a link to one of the youtube videos that show trailer swing when driving forward.

 

I watched the video. I believe you that there is a greater trailer swing when the tandems are all the way forward than all the way back. But I still don't fully understand this. Since the tandems are not a pivot point, I don't understand why there is more trailer swing with the tandems all the way forward.