A storage system (14) of a motor vehicle (10) presenting a cargo space defining an opening (18) for storing spare tires, tools, and the like. A load floor assembly (22) is configured to cover the opening (18) and to support various loads (41) positioned thereon. A cover (24) of the load floor assembly (22) is molded from a polystyrene or other foam composite. At least one laminate (18), formed from a hard board or other sheet material, is adhered to the cover (24). A support frame (40), formed from a foamed polypropylene, includes a density greater than the density of the cover (24) and therefore has a higher mass to provide a significant amount of structural benefits to the load floor assembly (22) for supporting and preventing a deflection of the cover (24) under the force of the loads (41) applied thereto.