Recently, the tyres and discs of your big rigs were split into separate components. SCS is extending the system to include hubs, hubcaps and nuts. That'll arrive for both games simultaneously, although the patch isn't dated yet.
After that, the options will be expanded still further with "a small but cool DLC", packing far-out nut designs and paintable components. Quite a nice complement for Euro Truck Simulator's multiplayer mod, I'll wager.