Dimensions required are as follows;
42 mm diameter centre. Knock off hub. Rudge Whitworth splines.
John, I'm not all that familiar with the terminology of the wire wheel sizes, but 42 is not the mm of the spline, but some type of a model number for that particular size splined hub.
Others can probably explain better.
So if you're checking with others just say a #42 spline and that should be sufficient.
I also did some checking many months ago and the Detroit wheel guy did reply but had to say nothing they had would work for a splined hub.
Now if that's the case and on the other 19"x3" wheels with a 5x4.5" and 5x5.5" bolt patterns, maybe someone can just use a stock un-laced new splined hub and develop a bolt pattern where the spokes get threaded in and then you bolt the wheels to the splined hub. It may take some machining to first make a flat surface on the hub and then a machined disc with the appropriate bolt pattern that gets TIG welded onto the hub to receive the new bolt-on wheel.
I know, tons of work for not much benefit. But sounds cool to have disc wheels instead of spokes.
