Towing by John Cadogan

He was doing alright until he started talking about trailer weights:

"Thing one (fully loaded trailer) is often called the GTM (for gross trailer mass) or the GVM of the trailer (for gross vehicle mass … of the trailer)."

It may often be called that, but it would be wrong - see discussion below.

"Both the vehicle and the trailer have a GVM - for the vehicle it means the fully loaded vehicle, and for the trailer it means - likewise - fully loaded. For the trailer, this is sometimes called the GTM - for 'gross trailer mass'."

Trailers DO NOT have a GVM representing the fully loaded maximum mass. GVM is a term defied in ADRs and applies only to motorised vehicles. The term for a trailer is ATM, for Aggregate Trailer Mass. That's also in ADR definitions.

And whether you call it GTM or "trailer GTM" or ATM, it CANNOT be equated to GTM. GTM is defined as the maximum allowable mass supported by the wheels.

I wrote a document for my club which explains it better than most of the stuff you find on line and in magazines.

Cheers