What's the story behind that? Got a link?

What's the mortar they're using between tires?

It's called an Earthship.

Essentially used tires and then a straw/sand/clay mix in between - at least that is what it looks like in between as a lot of times it is just packed mud. VERY efficient but not mainstream and laborious to build. The wife wanted to build one but I have bigger and better things in mind. Not made of tires so I'll keep it off this thread. (hint: concrete geodesic dome)

Here's a link of all different types of natural buildings including the earthship - How stuff works natural buildings

Apparently it's illegal here to use tires for landscaping, planters etc, so I doubt I could get away with a tire and mud igloo either.

Caption for the above pic:

Guy in Green shirt "Hey guys- I need a 235/75 15 to finish out this row"

Other two guys (looking for a 235/75)- "Sorry boss, but all we can find are a few 225/75's"

Green shirt, "Ahhh! It was looking PERFECT up until now- the gap left by a 225/75 will look terrible!- Let's just give up here and start it all over again over there!"

:D