Used tires in gardening?

Used tires in gardening?

Years ago, someone dumped a truckload of used tires on our land. (Rednecks are awesome!) I have an idea of using those tires as a border for a small raised garden in a corner of my yard. I plan to stack them two high, and make the tires themselves a sort of planter for tomatoes, rosemary, etc. My question is: Is this insane? Am I setting myself up for leaching chemical problems? Thanks for your input!
Repainting my boring walls

Repainting my boring walls

New

New

More views of my gardens

More views of my gardens

Angel wing Begonia

Angel wing Begonia

This is the most awesome thing

This is the most awesome thing

Grandmother’s Iris

Grandmother’s Iris