A trailer moveable by a cab includes: a first section including a cavity and a second section at least partially positioned within the cavity, where the second section is longitudinally movable relative to the first section, such that a length of the trailer is variable. The second section includes a cart including at least one wheel configured to roll along a floor of the cavity and a height-variable member co-acting with the at least one wheel. The second section is configured to move longitudinally relative to the first section by the cart rolling along the floor of the cavity. A towing system and a method for adjusting a length of a trailer moveable by a cab are also disclosed.