It is, however, prohibited for passenger vehicles which weigh less than 2½ tons unladen.
The new traffic signs regulations came into force then and prohibited the use of road signs showing restrictions in unladen weight.
It would be theoretically possible to give the same maximum operating weights to all vehicles of a given unladen weight.
It is arbitrary whether you say that the unladen weight of 1½tons or up to 2 tons should be exempt.
Our own criterion—which dates back a long time—has been unladen weight.
Heavy goods vehicles are usually regarded as those of over 3 tons unladen weight.
These are lorries of three tons unladen weight or less which have a permissible maximum weight of over 7·5 tonnes.
The 20 miles per hour limit for commercial vehicles of over three tons unladen weight offers precisely the same inducement.
