I must have an unusual tire because I do not have to add air all the time.I just checked a space front that I have and the front does not have a “safety” hump on it like the rear does.
The other issue on the rear is the tire itself. Unless you put some sort of tubeless tire on it it will always be leaking air. Tube type tires don’t have the membrane on the inside of the carcass that a tubeless has which is what makes it hold air. The raw rubber won’t hold air by itself hence the membrane. It may hold for a while but you will be filling them back up constantly.
All I can tell you is that it has been working for about 10 years. I do not remember what year I went to Moab but I went tubeless just before I went.