That’s the rim that I mentioned at the beginning of this conversation,
It has the engraved Schwinn script, and it was made of stainless steel.
I don’t know if Schwinn actually made that rim, but it was unlike anything else in their line up at that time.
In later years, the tires that were branded by Schwinn, were made by Carlisle.
So I wouldn’t doubt that the Zephyr tires mentioned above were made for Schwinn by one of the established tire and rubber companies at the time.
On the slight differences of the hooked bead drop centers mentioned above.
That was more of a year to year variation, than within a batch of the same year parts.
The profile changed between 1933 -1947
In the trade publications of the time, you would see advertising for drop center rims from Lobdell, and Williams in every issue.
I’ve seen plenty of rims with the Lobdell stamp and the later engraved script, but I can’t say, that I’ve ever seen a Williams rim.
They obviously sold enough rims to survive for decades, because they advertised in every issue of the main trade publication at the time.
So, I suspect, that some of the rims that we assume are Lobdells, were actually made by Williams.
There isn’t any branding on those rims to know for sure, except the occasional Lobdells that show up that still have their rubber stamp visible.