Only CO and ND allow 4 vehicle combination for towing triples according to the clicky link. It would be interesting how ND and CO lists the trailer types (first to last)....like a truck pulling a semi trailer/trailer/trailer for example.
A 4 vehicle combination is towing triples (three traiers).
A 3 vehicle combination is towing doubles. (two trailers)
And of course a 2 vehicle combination is tow vehicle pulling one trailer.
I bring this up because when asking your state size and weight folks a question on towing combinations we need to give them the correct info the way DOT laws are written on combinations.
Like the clicky says;
**Chart is not intended as legal advice and does not provide all regulations on the subject. Direct specific questions to your legal counsel. RVIA
assumes no responsibility for any inaccuracies or omissions.**
Which is good advise as what RVIA has listed for my state (Oklahoma) isn't being enforced at this time. Terms used such as a Suburban pulling a 5th wheel trailer and only a 3/4 ton or more can be used to tow combinations. Oklahoma DOT folks have said the Suburban/Vans pulling a 5th wheel trailer is too vague. And of course there is no way a officer can determine what a 3/4 ton vehicle is.
Call as I did and find out the skinny on combination towing in your state...or those you will be traveling through.