Sweden has a long experience of using longer and heavier road transport vehicles than in the rest of the European Union. The interest in efficient transport has also been expressed by field tests using vehicles with a length of 30 meters and 90 tonnes gross total weight. In this paper the socio-economic effects of using larger vehicles are evaluated. One case concerns Sweden’s exception from the EU standard and includes effects from all types of cargo while another case analyses timber transports with larger vehicles than the ones used in Sweden today. The general finding is that larger vehicles can be cost effective even when external costs like road deteroriation, traffic safety effects and air pollution is accounted for as long as no investments to improve the bearing capacity of bridges are required. It is recommended though that larger vehicles are used mainly on larger roads, use Electronic brake system (EBS) and that the condition of brakes are guaranteed. Traffic safety can also be improved by better facilities for drivers to rest and more distinct signs indicating the larger dimensions of the vehicle.