As was state above, "G" can mean a number of different things. Their is "G" scale and "G" gauge. It can mean different sizes based on the manufacturer being North American or European and even the same manufactures offer different "g" sizes depending on which line they offer. "G" can mean anywhere from 1/20.3, 1/22.5, 1/24, 1/27, 1/29 or 1/32 scales. The Aristo-Craft Road Railer series in the video above is listed by the manufacturer as 1/29th scale and I think it is actually closer to 1/32 scale from my estimation from seeing their models at a local hobby shop. furthermore, the trailers, in my opinion do not have the level of detail the 1/24th or 1/25th scale truck modeler would accept. Rudimentary suspension and wheel detailing. Unfortunately, the most detailed model railroad semi trailers I have seen have been the Model Power 1/24th scale 40 foot trailers and they are lacking in our standard of detail.
Nice try Ben, but as of yet the only, some-what modern, North American styled 1/24th or 1/25th scale semi trailer model currently available to us, not counting the old Ertl and AMT kits is the Italeri American 48 foot reefer kt. You can always massively correct that kit or totally scratch building a trailer.
Hopefully if we keep badgering Italeri and our new friend, Moebius Models, they will capitulate and offer us that 53 foot semi trailer we all need to make our tractor models complete!
Check out his incredible Intermodal "G" scale train layout!