A floor assembly for a trailer includes a pair of longitudinally extending main beams, each having a first height dimension along a first longitudinal portion of the main beam and a second height dimension along a second portion of the main beam. The first height dimension being greater than the second height dimension. Cross members extend in a transverse direction between and connect the main beams. A plurality of floor members extend transversely between the main beams. The floor members including at least some reinforced floor members. The reinforced floor members have upper and lower walls and opposing side walls that define a rectangular cross-section and include a series of truss walls extending angularly between the upper and lower walls. The reinforced floor members are positioned on the upper surfaces of the main beams at least in part at the second height dimension.