I didn't realize there's a forum for containers, so I'll just put the link here:

The thread "Re-purposing old semi-truck brake drums as flower pots." in Tools and Stuff forum

Great idea cover the axle hole and the lug holes are drain holes.
I recently scraped some from a old s10 not as big but would gave been good for succulents.

herrwood said:Great idea cover the axle hole and the lug holes are drain holes.
I recently scraped some from a old s10 not as big but would gave been good for succulents.

I was thinking some galvanized mesh would work for the axle hole. As for myself, the placement would be have to be carefully thought out because of the weight, especially after soil is added. But then, I've moved other garden stuff with the help of a hand-truck when I had to.

Definitely would need a hand truck.
Once they are full of soil it could be used for a Olympic lifting event.