Yes, I have been thinking about it, but have not had time to measure any wheels and hubs.

Just my preliminary guess is the slip fit of the bushing/adapter on the hub should be only a few thousandths if any, or almost an interference fit. Ideally because the wall is so thin and the relatively large diameter will allow it to grow if heated slightly, you could plan on no clearance, or a slight interference fit the heat should allow it to about drop on.

The wheel fit to the adapter should be reasonably snug, I am guessing 0.005" to 0.015", but best to keep it snug. 0.030 sounds like way to much.

If you can wait till next week I can remove the rear wheels from my truck that has a 1988 Dana axle with the nominal 5.25" hub diameter, and measure it with a micrometer. Then this would be the outside diameter to shoot for, as it is what the factory did.
I could also pull the wheel off my old axle with the nominal 4.75" hub and accurately measure that too, that will give a good idea of what the ID needs to be. In reality it would be a good idea for everyone to measure their hubs and make the adapters to perfectly fit each hub. Once you get 8 or 12 measurements you can decide of they are all close enough to make adapters on speculation that the rest will be the same.

Again, if you can wait till next week I will have time to do some measuring.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-