Wheels are decorations you'll be able to get by using special pieces, which you'll be able to obtain in the chests. As you obtain pieces from the chests, you'll be able to unlock different designs that you'll be able to equip to improve the aesthetics of the wheel in your games.
If you enjoy collecting objects, don't miss the wheels! All you have to do is play games to get chests; each chest will provide you with different pieces you'll need to unlock new wheels.
You'll find the "Wheels" section in the fourth icon of the lower bar in the game's main screen.