Earthship foundation

Hi everyone
I would like to ask you about earthship foundation. I know original earthship has no foundation. but I am going to build it in Poland and because of the climate i have to. My Idea is to do strip footing but not with concrete but out of tires instead like an earthship- and than fill it with sand and than put a thin concrete layer on the surface- like the classical strip footing does. or maybe do you have another ideas? what do you think?

Some questions;
- why sand and not concrete?
- why the tyres. the sand would sit in a trench ok.
- are strip footings actually required?
Some other thoughts;
- concrete spreads the loads out and tend not to crack or sink, something that sand may not achieve.
- Earthships consume an enormous amount of labour, are you aware of that?

I am having similar thoughts. Building a pier and beam in Texas and have convinced myself rammed earth tire walls(as beams) are the way to avoid the concrete usage. I kicked around the idea of piers from stacked tires but a couple of engineers have steered me away from that. I would love to hear if you find any other info and or an engineer firm that would be willing to sign off on a design. Either way I am going for it, breaking ground in the 27th!