A grain storage container in a combine harvester comprises a front panel, a rear panel, and a first side panel mounted fore and aft on a lower hinge assembly. The first side panel comprises a top edge and a lower edge that form a non-zero angle relative to each other. First and second foldable materials couple the first side panel to the front and rear panels. The first foldable material is attached to the front panel and the first side panel. The second foldable material is attached to the rear panel and the first side panel. The front and rear panels further comprise a respective first fixed portion coupled to a respective pivotal second portion. Each pivotal second portion is coupled to the respective fixed portion. A front-facing surface of the second portion of the front panel and a rear-facing surface of the second portion of the rear panel in an expanded grain storage container position are adjacent to an interior surface of the first side panel in the grain storage container configured in a closed position.
