The post by ped4599 is quite noteworthy. On the other forum, I think Ahmed started a thread
regarding mounting tires on the roof rack. In the event of an accident, will the tires stay put?

After reading Ped4599's post about the rack coming apart, I think this is of serious concern.
Perhaps someone with the ability to research roof top tire mounts should offer a solid stable mount.

Or at least a warning.