Turn the tire over. This will form a vase shaped urn. Paint the tire and rim with a matte finish outdoor latex paint only. A dark green, red, or charcoal grey is fine. Fill bottom of wheel with gravel about one third, then fill the rest with a top-soil mix of soil, peat, and vermiculite.
Many urns fail because the soil mix is poor.
Grow anything and everything you want from vegetables to flowers to small trees. Fuschia, coleus, impatiens are particularly good for shade. Portulaca and even cactus do well in sun if you have a habit of forgetting to water. For sun-petunias, salvia with white Alyssum makes a real nice show. Your imagination can run wild.