Richard,
The round plates (inner white & outer red / black numbers) on the back of the truck are about the speed limits for trucks in the EU.
All the commercial trucks with weight over 6 tones, are allowed to travel at a maximum speet of 90 Klm per hour.
There are some kind of loads (oversises, chemicals) that are allowed to travel at a maximum speed of 80 Klm per hour.
As already mentioned by Chuckyr, Euro lenght laws restrict the total lenght of the tractor/trailer up to 18meters (60ft).
Thats why all the European makes are COEs. Volvo in the US market is just an exeption.
Scania has a legentery history on convetionals with great trucks running all over the world. The letter ''T'' is for coventionals meening torpedo. Mostly the conventionals of SCANIA where prodused for ON/OFF road usage or if you want, for the construction industry. But there where also many ON road units used form companys or owner/operators what they work hauling ship conteners (max 40ft) or tankers because those trailers are much sorter that the vans or the reefers (remember the lenght limit)
SCANIA, IVECO, MERCEDES-BENZ, MAN have also a long story in other countries like Australia, Argentina, Chile and Brazil. If I am correct all this makes have their own factories and production lines in Brazil.
Hope this helps you...
Kostas.