the markings will be to remove them from any liability claims from people that choose to run them on road vehicles, we have the same sort of thing here where stuff that's not legal on the road is marked off road use only
Hehe that's one time where i feel legislation here are spot on, you cant legally put on larger diameter tires, but i don't think our law are so much from the larger tire perspective but more for the increase in ride height it give, and here you cant lift or lower your car much.
BUT ! these are laws cops don't seem to bother much with, my friend when he got his Dodge ram charger it was fitted with pretty big wheels, and he did get pulled over using them but just so the cop could admire his nice truck.
He even got the car inspected with the suspension lift "kit" installed to make room for those big tires, which again document the widespread incompetence here, but at least not public this time as vehicle inspection places have been privatized.
I think it is okay to legislate against stupid, but sadly it seem like Danish politicians have little to no faith in Danes intelligence and so go overboard on the legislation part, completely forgetting they them self are Danes too.
And i do feel it is very stupid to have a society where a great number of the laws are ones most people couldn't care less about, let alone the police that are supposed to uphold said laws.
To me that's the jump off point on a steep downward spiral that's the description / recipe for a society that are "attached to another object by an inclined plane wrapped helical around an axis" ( screwed )