American Truck Simulator is bringing a wider range of semi-trailer lengths compared to what we have in ETS2 now. The longest variants and the overall resulting length of the whole tractor-trailer pose an extra challenge for navigating tight intersections and maneuvering at the cargo drop-off points.
Consider the comparison image above - it's clear that the driver of the big rig on top will have a considerably harder time getting through tight bends or taking a turn on a narrow street. Often the shortest path through a city may not be the best path to reach the destination without risking damage to your semi. The same cargo delivery point which seemed easy with a shorter trailer before can become a nightmare when you come next time with a 53-foot trailer.
A trailer's axle positioning will also challenge the players to expand the skills they are bringing over from driving trucks in Euro Truck Simulator 2. Double axle configurations are more common in the US, and certain configurations of axles will have a different tendency to jack-knife.