Balancing the wheel

 

You can't usually see them because they are covered by the hub cap but car wheels have small masses added to the rim in certain places to make sure that the wheel is balanced. By that, we mean that as it rotates it doesn't wobble due to some parts being heavier than others. This is back to the moment of inertia issue from the last post. This article explains the physics very clearly https://en.wikipedia.org/wiki/Tire_balance This has good diagrams https://e-quipfix.co.uk/wheel-balancing-101-static-vs-dynamic-wheel-balancing/