Not to jump the gun on Penny, but wanted to say. Long ago I made a few of these for an Individual.
View attachment 2034376
They painted them with house paint on exterior , and looked good.
Here is a site that explains how to do such.
https://www.instructables.com/id/How-to-Make-Blooming-Tire-Planters/
These are cool looking, but I don't think this is what Penny does. I think she uses the actual tire as it is and fills them with dirt/compost and plants them.