I doubt you need anything radical. The bikes seem to be OK, but probably aren't getting any routine care. Probably all they need for the tires is a few spare tubes, patch kit, tire levers and a floor pump. Then it's just a matter of training someone in basic bike care.

The fact that the bikes are stored indoors in a block building says that these folks are far better off than many others in Africa.

You might also want to check in with the folks at Bikes not Bombs for more insight into what works and what doesn't.