Wheel center cap measurements for merlot/gleneagles?

Hi,

    I have one wheel cap remaining on my Gleneagles and had been looking to get replacements.

 

Unfortunately for the time being I’m unable to remove the wheel to get the cap out to measure it properly to see what the caps measurements are.

 

I thought I’d be smart and measure the outer side of the remaining cap, which shows on the ruler as 40mm diameter.

 

Great, I thought, however as a precaution I then measured the hole it goes into on the wheel - 50mm.

 

So now I’m confused, how can a 40mm cap fit snugly in a 50mm hole 

 

Would anyone happen to know the measurements? I did wonder if the eternal flame mk2 wheel caps that were on ebay:

 

eBay Link

 

would fit, if they do that’s an annoyance as I didn’t bid, but at that time they were 51mm and the cap measurement I had was the 40mm.

 

Thanks.

 

Any photo,s

Sorry for the late response, I did manage to get a photo taken and I see that there’s a cap, on the cap - looks to me like two domes, so when I measured I only got the top cap measurement of 40mm for the 50mm hole. Hopefully the attached picture will show what I mean.

Does anyone know if this is a genuine cap for a merlot/Gleneagles because I could possibly fabricate myself something similar to match, but if they’re not how they should look I wouldn’t bother.

Thanks.

Edit: What a lousy photo of the ruler, couldn’t find my easier to photo ruler so had to use that one but it does in that picture read 4cm.