Hi Nigel / Izzy,
Unfortunately the C Class doesn't have the thick bearing surface as per the jinty and earlier models and is a metal wheel with a central insulating bush on a 2mm? axle which runs in bearings.
And on reflection I agree that unless you held it in place with a rotating centre its likely to upset the insulating bush or rotate on the axle.
I have a lathe with Digital readout so no excuses there and have a ER16 collet set which goes up to 10mm and some blanks. I have machined wheels before but only to reduce the tyre and flange width.
Nick,
Thanks for the information, I will ask on the groups.io if he fancies doing another alternatively I would like to know how he did it. I saw a close up photo of his own br black example and its looks quite superb.
Guy