[Cob] Tires For a Foundation?

[beno]

Amanda Peck wrote:

>
> My problem with the idea of tires as a foundation for much of 
> anything--except more tires--is that there are going to be places 
> where the circles just touch--how did you plan on 15-20" cob walls 
> spanning this?  

What my idea was is to simply backfill the area inside the circle with 
rammed gravel. Your idea of cutting off the tops of the tires is a good 
one. That makes them easier to ram AND easier to screw together. If 
necessary, we'll screw them to a circle of tires behind the main circle 
to cut down any movement. Then I believe the whole foundation would be 
stable. And thanks for the links!

As I re-think this, perhaps a row of tires behind isn't necessary. 
Perhaps rebar rammed into the earth in front of and inside-behind the 
tires would be sufficient. Thoughts?
beno