Mahle 4-lug wheel dimensions..., Center hole diameter? Options

[BadBrain]

Does anyone know what the center hole diameter is supposed to be for 4-lug Mahle's?
Because my wheels have two layers of powder coating and I already had to grind some of the paint away on the inside recess, in order to have them fit on the center rim (front) of the brake disks.
I need new center caps and would like to know if the diameter is actually 2 1/2" (I measured 2 1/4" diameter for my exterior wheel holes).
Thanks in advance,
J.

[Cap'n Krusty]

If your car is a '73 or newer, the center opening is CRITICAL, as that's what centers the wheel for mounting and balancing. Just sanding or grinding doesn't get it ......
it needs to be machined back to whatever the standard size is.

The Cap'n

[BadBrain]

Thanks Cap'n, please let me clarify what I am looking for.
There is the inner diameter of a Mahle wheel (shown below):


And then there is the outside Diameter of the center hole (shown below), measuring 2 1/4":


I understand that the inside is critical as it has to fit on the brake disk rim, but the outside doesn't. (Besides, the hole opening doesn't seem to matter for the rear mount, because there is no rim or anything and it is going to be adjusted per the bolts)
So again, for the front, it was less critical to grind off the paint (not the aluminum) with a precision tool on the inside and the rear didn't need any alteration.
So, I wonder if I will have to find 2 1/4" center caps for the "outside hole" or if this is just because of the paint and it is 2 1/2" in reality?
Thanks,
J.