Place the tire on top of the soil in a sunny location that receives six to eight hours of direct sunlight a day. Full-day sun is preferred since these heat-loving plants thrive in the summer sun.
Select a bush cucumber for best results. These plants typically grow upright with short vines. Regular vining cucumbers can be grown if you allow vines to trail beyond the container or use a trellis to keep them upright.
Fill the tire to within 1 to 2 inches of the rim with a lightweight potting mixture. Soil made from equal parts garden loam or potting soil, perlite and peat moss works well. Add 1/2 cup 10-10-10 fertilizer and 5 tbsp. of dolomite limestone per bushel of soil mixture. Mix well.
Plant two cucumber seedlings in the center of the tire, spaced approximately 4 inches apart. This allows room for the plants to grow and produces enough cucumbers for a typical family of four for table use.
Water thoroughly to saturate the soil. Water again when soil feels dry 1 inch below the surface. Cucumbers are heavy feeders and require moist soil. Lack of water, particularly during fruiting, decreases yield.
Apply water-soluble fertilizer on a seven- to 10-day schedule throughout the growing season. Follow the application rate on the container. Container-grown vegetables require more frequent fertilizing due to leaching of nutrients through the bottom of the container when watering.
Harvest cucumbers when they are 4 to 6 inches long and slender for the best flavor.