[Cob] Tires For a Foundation?

[beno]

Someone commented that I would need to build the walls 20" tall before 
cobbing to protect from moisture in case of flood. Sounds like good 
advice. They also indicated that filling the tires with caliche stones 
would spill out if the tires were stacked one on top of another. 
However, having played a minute in Photoshop creating tires, I don't 
think this appears to be much of an issue:
http://web.vi/tire_stack.jpg
Just use big rocks where the holes are. Furthermore, Michael Shealy has 
built an entire house this way and rammed earth in instead of rocks:

http://www.touchtheearthranch.com/tirestart.htm
So, perhaps it's worth a try. Of course, I don't want to waste effort trying if it's in vain, so I await your experties.
Thanks,
beno