But here we go, these are the parts:
-Hub: chrome or black
-Spokes: 3 or 4 spokes
-Spokes: chrome or black
-Handle: walnut root wood, oak wood, bleeched oak wood, black stained wood, or black leather
-Bolts: chrome or black
-Hub cover: walnut, oak, chrome or black (or none)
-Hub trim: chrome or black (or none)
-Rivets: chrome, black, or white (or none)

27 parts, 3,600 possible combinations

How to
-Select a wheel base like any other steering wheel. It will be only a chrome or black hub in this case. But red attachment points will appear.
-Now use the red addon attachment points. Pay attention to the icons that show what parts go where. Or refer to the image in the gallery.
-Use the four outer red addon attachment points to add knobs, just like you can with all the other wheels

Update: 1 Nov 2022
-Overhaul of how textures appear in various lighting conditions

Credits to mpie