I would imagine that tires are not a good idea to use as a pot all that oil leeching 

Found this picture on the internet 

 

Great idea for those growing in wet areas. It looks like something I would do.

and what would you fertilize with? LOL

You don't want to know!

Those tires look like they still have tread on them... what a waste.  Lol.

Very creative.

What would you use for uppotting? Truck tires?

Hi,
What if the upper or middle tire slips ? Someone pushing, or with the wind ?
The idea is not bad, but simply using an 80 Liters trashcan is in my opinion safer and prettier.

Igor, I love your thought!

I have some painted ones with flowers on top of my rockery... I like it... here is another example.... all recycling is good and yes, the black rubber makes it hot. may not be good if you are already in a very hot area... hopefully, each tire holds a bit of water for the plant.
https://www.google.com/images?q=flowers+on+tires&rls=com.microsoft:en-us:IE-SearchBox&oe=&gws_rd=ssl&hl=en&sa=X&oi=image_result_group&ei=cwJVVKgOqduJAsbfgdgB&ved=0CB0QsAQ

greenfig you can use this tire 

 

[QUOTE=jdsfrance]Hi,
What if the upper or middle tire slips ? Someone pushing, or with the wind ?
The idea is not bad, but simply using an 80 Liters trashcan is in my opinion safer and prettier.

[/QUOTE]

Looks like the white PVC pipe goes down through it.  It is likely very stable, and more so the longer it is there.  Plus its probably full of soil, not lightweight potting mix. 

Repurposing is good.  Though I still say some of those tires have some good tread!  ;-)

I dont know if i would be eating figs grown in that pot

When it's time for the fig shuffle you can just roll it into the garage......Brilliant!!! (now for some reason I want a Guinness)