These are based on British classifications:
Weight is tonnes or "t".
First: goods [box or delivery truck] https://wiki.openstreetmap.org/wiki/Key:goods
Second: hgv (high goods vehicle) [semi-trailer or large truck?]   
Third: hgv_articulated [semi with 1+ trailer]  https://wiki.openstreetmap.org/wiki/Key:hgv 

Don't feel bad I have to figure it out too. Already updated, close note after reading.