Question.
If you change the colour of the original alloys is that classed as a modification by the insurance companies?
Or could you argue that the car was supplied with the wheels in that colour? As technically you havnt put aftermarket parts on it?
Absolutely tell the insurance company. It depends on who they are tbh, I have been insured with 4 companies now and 2 of them noted a colour change as a modification. If I had claimed then they would have denied as it wasn't like that from the factory ( Codes on stickers in the boot correspond to optional extra's ). You can argue all you like with them, but they will ALWAYS win.