To Stevec22:
I dont beleive the 5th wheel really has anything to do with it as trailers do sway that are attached to 5th wheels (doubles and Triples) because of the short distance between the pivot point and the axles and because as I said in my post the turning factor of the dolly.
And I have seen many a 5th wheeler TT going like mad swaying down the road.
And that really wasnt why I mentioned tractor trailers. I was using the tractor trailer comparison in regards to the weight ratio between the tow vehicle and the Trailer...because many seemed to indicate sway was a function of the tow vehicle weight vs trailer weight..
Your comment about speed is interesting. Generally while traveling forward with some pull, the trailer should not sway whether you are going 35 or 65. Its when you drive erratically, change lanes abruptly, brake without trailer brakes adjusted properly that you get the sway.
However if you really want to haul your TT at 70+mph then aerodynamics may come into it and you may experience some lift under the trailer which may induce some sway...where exactly that speed point is is different for every trailer I am sure. I do agree that speed certainly can be a factor.
