Rally wheel backspacing

So now I'm reading that I should have my wheels balanced lug centric and not hub centric.  That may be why I can't get rid of this little shake at 52-54 mph.

Also, in looking for wheels at all the aftermarket places, their backspacing measurements are all over the place.

I measured 3 of my wheels and from the bead it is 3 5/8" and from the lip it is 4".  The 3 5/8" goes along with Adams Apple's "B" measurement as the steel is probably about 1/8" thick.

Geez Louise.

Have you considered a road force balance?

Yeah, I can do that, but with steel wheels, lug centric balancing is better than hub centric as the hole in the middle isn't as precise as a machined alloy wheel which is balanced with a cone centering the center hole.

What is annoying is Ecklers sells the Corvette 15x8 rally wheel with a "correct" 4.25 backspacing but then says a 1/4" spacer is needed.

Mid America sell the same factory "correct" rally with a 4.25 backspacing and never mentions a spacer.

And they are obviously measuring backspacing from the wheel lip and not the bead.

This is maddening.