From the tail wire (stooge loop).
They hang out like a bunch of bats.
Heard long ago to hang them like that to prevent oil migration in wood or oil clot forming at tank pickup.
If worried about the greasy wheels staining the walls (foam tires), I put post it notes under each tire. Stooge loop has to be pretty secure, so you can jostle them around safely in place when dusting or if you change a prop, etc.