Originally Posted by Bikedued

That looks like the bottom edge of a knurled sidewall. I have a set of those rims, they make an interesting whizzing sound while braking. On this particular set of rims, it looks like it is all but worn down, just leaving the outer and inner edge. This type of sidewall is more common on 70's Rigida steel rims, but there were a few made by Weinmann in alloy. Although the only two sets I have seen are mine and the OP's. There are certainly more out there.,,,,BD

Mine are nearly NOS quality, and I am now thinking they will look amazing on my Geoffrey Butler project. After all they're rebuilt with butted spokes, and the rims are shiny as all get out. The large flange hubs will definitely look the part.