Catalyzes the epimerization of the C3' and C5'positions of dTDP-6-deoxy-D-xylo-4-hexulose, forming dTDP-6-deoxy-L-lyxo-4-hexulose. dTDP-4-dehydro-6-deoxy-alpha-D-glucose = dTDP-4-dehydro-beta-L-rhamnose Carbohydrate biosynthesis; dTDP-L-rhamnose biosynthesis. Homodimer. Belongs to the dTDP-4-dehydrorhamnose 3,5-epimerase family.