The Grey hub caps are for non-premiere trims. I think 20 inch wheels get a different hub cap.
I was at Tustin Nissan this afternoon. All 3 Ariya Premieres are in the showroom. Linda happened to be walking by in the showroom while I was sitting inside the Ariya. I told her you must be very busy becsuse your name is plastered all over this website.
Anyhow, the 19" copper hubcaps are standard. The 20" gray alloy aluminum wheels are an upgrade per Parts Dept. Bummer! I was hoping to have the 19" gray hubcaps swapped onto my Pearl White. It is confirmed that the gray wheels are aluminum 20" wheels and not just hubcaps.