Most state gross weight laws only allowed 58,000 during the 50s. This could be achieved with a single axle tractor and tandem trailer. These laws changed to 73,250 in the late 50s. Chevrolet tandems appeared in the mid 50 as vocational trucks. Chevrolet really didn't become a player in the 5 axle market until they came out with the 409 engine, but drag axles were used on 3 axle tractors.
