Vehicle tailgate assembly that includes a sill flap and tailgate, where the sill flap has rollers that contact the tailgate while the sill flap and tailgate are opened or closed. The sill flap thus maintains rolling contact with the tailgate during opening and closing operations. In embodiments of the disclosure, the tailgate opens to leave a gap between the edge of the vehicle bed and the edge of the tailgate, and the sill flap is pivoted into this gap. While being pivoted into this open position, the sill flap rollers rotatably contact the tailgate, so that the sill flap maintains rolling contact with the tailgate rather than frictional contact therewith. This prevents damage to the sill flap and tailgate when opened and closed.