I have had those and the Kelsey Hayes (no lock ring).Kelsey Hayes also had them in 19,18,17,16 &15".Adjustable ,meaning the spokes are not welded but laced like a motorcycle or bicycle rim. That thin outer band is a lock ring and yes necessary.Brian mentioned that they crack around the lug holes.That is because a spacer ring is required to mount them on a 32-35 Ford mechanical brake drum,much like if you mount a 40 Ford wheel on a 32-35 drum.