It is nearly impossible to fill a tire without cutting out the top wall. If you don’t, it takes twice the time and effort, and when the clay dirt settles, there is always a small gap remaining. By cutting away the top, you can fill the tire with dirt and tamp it in using a standard concrete tamper. This makes for a really solid and awesome foundation. Cutting out the side wall of the tire is easier than most people think. If you use the saw to cut a hole and start in the soft part of the tire just below the steel belt, it only takes about a minute per tire. We use a reciprocating saw with a short all purpose blade, but any blade will work. As in the first photo, lay the body of the reciprocating saw on the side of the tire with the blade touching the tire wall just below the treads. Start the saw and hold the blade in one spot until you make a hole big enough for the blade to fit through. Insert the blade in and cut out the side (it cuts like butter).
When finished, you can save the cut out side for something else, or place it back in the bottom of the tire before filling. We use them to hold down tarps. We have also linked them together to hold back a hill in order to plant ground cover.