'30-'31 side mount tire plate
 

The attached photo shows my side mount plate(s) with original studs filed to slip in the square holes as suggested in some posts or easier install. As in a prior post, I noted that the plate has a slight curve towards each ouside corner. Also, some have suggested that the projected boss at the elongated hole faces inward towards the car body. The studs before removal were installed in the opposite direction so that the raised area was towards the arm. Could this be an after market plate? The new repro plates according to some vendors are flat with no curves or bends. Also, before, when installed with the raised area facing outward, the wheels in the wells were canted inward slightly, as the plates perhaps were mismarked R & L.
Any further thoughts?