It would be pretty lethal to have an empty van and a 3T trailer!I've been investigating my GVW, GTW, etc on the Motorhome in the last few days actually as a precursor to getting a weight uprate ...
Post Motorhome conversion, Autotrail state the GVW and the GTW - but they do also state a max towing weight as well - which is GTW minus GVW. So that does
mean like Nabsim says, you can't take spare capacity from the van and put a greater load in the trailer.
As far as Panel vans go, my VW LT was just the same - the VIN had a GVW of 4600 and a GTW of 6600, and the handbook stated a maximum towed weight of 2000. So no weight loss in the van to allow a heavier trailer allowed there either.
The info is not on the VIN plate, but very likely in the drivers handbook and I bet your Sprinter will have exactly the same stipulations as my VW and Nabs Mercedes.
The phrase ".....any spare weight capacity can be used by the trailer, so long as the GCW and trailer GVW are not exceeded" could be key, but what it the manufacturer has implicitly stated a towing limit? Their design limit will superceed that phrase I am sure.
Note the wording earlier in that sentence also ... "To help find ...". So guidence only.
PS. I was not familiar with the term "GCW" so I did a search .... something the unwary need to watch out for - the term GTW has two different (VERY different) meanings when it comes to towing and weight limits. In the UK, GTW = Gross Train Weight, yes? In some other countries, the term GTW changes to GCW - Gross Combination Weight and GTW changes meaning to Gross Trailer Weight!
e.g. On-line info such as:
"Gross Trailer Weight (GTW) is the same as Gross Vehicle Weight (GVW) when referring to a trailer. Again, the only way to accurately determine the GCW is to drive the entire assembly on a scale."
"Gross Combination Weight (GCW) – Equals GVW plus GTW."
something for the unwary to become aware of if searching the web for info on trailers and weight limits.
Little extra bit ...
Picked this paragraph up from the What Car website:
"The popular Mercedes Sprinter only has a towing capacity of two tonnes, but as with most Sprinter vans there is an option for everything, and a special reinforced trailer coupling can be specified to transform the maximum into 3500kg, which makes it far more versatile"
So Mercedes are saying to tow over 2000kg and upto an extra 1500kg, you need a special reinforced trailer coupling. If the GTW limit was as simple as the trailer can be any weight as long as the GTW is not exceeded, the driver could have an empty Sprinter and likely tow 3000kg. So why the need for the reinforced coupling?
Isn't there a legal max ratio for trailer to tow vehicle weight?