In ETS2 version 1.32, SCS implemented a weight per axle limit, configurable per country. This by default only works up to around 5 axles (depending on the country). Since these road trains have up to 18 axles, the default configurations by SCS are not sufficient. Basically, this causes the game to classify every trailer with more than ~5 axles, as a 5-axle trailer. Since the weight limit for a 5-axle trailer is way lower than the combined weight (trailer + cargo) of most of these road trains, the game reduces the cargo weight to, in some cases, even 0.

There are a couple of changes I, as a modder, could implement to get around this weight issue. I have listed the most viable options I could think of here, including their disadvantages:

• Define weight limits for every axle count up to 18 axles, for every country. This change will allow the game to properly identify the axle count of the road trains. The disadvantage of this solution is that every country configuration file will be replaced by this mod, which can easily cause incompability with other mods.
  
• Define a "overweight: true" attribute for every cargo which can be transported in the road trains. This change will make the combined trailer weight completely overrule the country weight limits. The disadvantage of this solution is that every default cargo definition file will be replaced by this mod, which can, again, easily cause incompability with other mods.
  
• Add a separate cargo definition for every cargo which can be transported in the road trains, with the "overweight: true" attribute. This is currently the only solution which will not cause incompability with other mods. The disadvantage of this solution is that maintaining the separated 500+ cargo files requires an insane amount of time and work. Apart from that, it adds a whole new set of definitions for every cargo, instead of using the SCS cargoes, which can be considered junk files.

Let me know your opinion on the solutions described above, or if you know another solution. Although a fix would be pleasant, it shouldn't be too important. This mod is not meant to be realistic, after all.