Vehicle and trailer length

"A motor vehicle, other than a bus, with or without a coupled vehicle may not be driven on roads other than private roads if the vehicle or vehicle/trailer combination, including load, is longer than 24.0 metres. The length of a vehicle and trailer combination, including load, may however have a maximum length of 25.25 metres if the following conditions are fulfilled"

Some conditions

Every vehicle included in the road train is equipped with antilock brakes and coupling devices prescribed by the Swedish Transport Agency
Every trailer included, except for semi-trailers, has a maximum length of 12.0 metres.
Every power-driven vehicle included has a maximum length of 12.0 metres.

Swedish trafikförordningen