Overlaps occur on both objects when one hits the other as far as I know. So just ha dle the overlap on the one that makes most sense to you.
Remember your collision channels need to be set up to match between both objects, object/collision type and channels of types it can overlap with. Also both objects need a component that has a collision primitive in it check the static mesh assets for both to make sure, although in the case of your wheel I am uncertain how it will go with the invisible collider components.
Make sure all the actors or components involved have their Generate Overlap Events checkbox ticked.