I haven't ever tried it myself (lack of yard), but my Granny used to stack worn out tires and fill them with hay to grow her potatoes in. The hay made "digging" up the potatoes very easy (especially with clay soil) and it's a good way to get extra mileage out of tires.

I have heard of this. Only instead of hay, they added more dirt with each tire. I am thinking of trying it next year!

I did try this one year, and it is great way to grow potatoes if you have limited space, plus harvest is very easy, you just knock the tires over and pick up the potatoes. There have been many discussions about this before, doing a forum search brought up these Forum results If you are interested in reading more about this.

I fill tires with compost to grow my pumpkins in. Works great for pumpkins...I never thought to try potaotes that way!

Thanks Comfrey! So helpful that you can point us new people in the right direction! I am making lots of notes about all the stuff I want to try next year and this is definitely on the list!
Amy

You are welcome Amy!!!! Keeping notes is great way of learning and remebering things, I have been gardening for many years, and I still write new things down I find or want to try/remember. Be sure to post your results on using the tires when you do this, that is how we learn is from our own experiences and others. It is a fun way of growing things, esp if you have a bunch of old tires laying around, or most people will gladly give them to you to get rid of them.