What causes a trailer to dogtail?

By dogtail I mean when the trailer tandems are tracking to the left or right of the trucks wheels, when you are driving straight.

Sometimes I might have the drives right on the shoulder line, on a straight away, and the trailer tandems are 6 inches over the line.

I just had one trailer that was not dogtailing, then i got onto some back roads where i had no business being. And ran over some curbs and such. Then after that it was dogtailing right.

 

It think it has something to do with the pins that lock in the tandems getting twisted.
Like maybe the tandems get kinda sideways, which makes the trailer off track.

I have had plenty that do it, but this one did not dog track, but after i was done with it, it was dog tracking.


And It's the companys fault. They sent me to this rinky dinky town in PA. And this place was 20 miles from any major highway. And i had to take roads that didn't even have numbers, just names. The lanes were just as wide as the truck, i had the outside tires hangin off the side of the road.
hairpin turns, where you better hope you don't meet any oncoming traffic.

I felt like i was on the death road on ice road truckers.

I did meet a minvan on one turn, she had to back up to let me pass.

But there was no good way to get in and out of that place. Its so hard to tell if a road is good or not just by looking at it on the map.