Introduction: Concrete Tire Piers
Some projects require a sturdy base or anchor. It is possible to easily make concrete tire piers that are heavy and secure enough to support and anchor the project to the ground. You may need one of these for a tetherball pole, or two of these for a volleyball net or three of these for solar panels or four of these for a swing set. This project demonstrates a simple way to make moveable yet secure concrete tire piers using recycled, worn car tires and concrete. The tires serve as a mold into which wet concrete is cast.
Step 1: Tools and Materials
I have tried to make this project as simple as possible, keeping recycling in mind and using tools, materials and technology that are within reach of most people. Those with access to specialty tools and materials could certainly do things differently.
In this project I am making 4 concrete tire piers, to support wooden beams, using worn tires from my small car. However, I am only providing instructions and a material list for just one concrete tire pier.
Wheel barrow or cement mixing tub
Steel trowel or putty knife
3/4 inch (20 mm) metal pipe, 3 or 4 feet (.91 or 1.22 m) long; 2 needed
Materials Needed for 1 Concrete Tire Pier:
Rebar supports: 2
3/8 inch (10 mm) rebar, 12 inches (305 mm) long: 3
Old tires: 2, one for the pier and one for the mold. They should be roughly the same size.
40 inch (1 m) roll of tar paper: 1 roll
Duct tape: 1 roll
Plastic garbage bag: 1
Ready-mix concrete: 2- 60 pound (27 kg) bags
Metal anchor suitable for your project.
Step 2: Preparing the Tire for Concrete
To prepare the lower tire for the concrete use 2 rebar supports (shown in Photo 1) which can be found in the masonry section of hardware stores. The sidewalls of the tire are angled inward making it more difficult to push wet concrete inside of the tire. The rebar supports help spread open the sidewalls of the tire. They also add metal reinforcement to the concrete. Position the rebar supports so that they hold up the edge (bead) of the tire as seen in Photo 2.
Step 3: Bending Rebar
The next step is to bend the rebar which will be used to further reinforce and connect the upper and lower portions of the concrete pier. We will use two steel pipes to bend the rebar into the shape of an "L".
Lay one of the pipes on the ground. Insert the rebar into the pipe leaving 4 inches (102 mm) of the rebar exposed. With one hand, hold the rebar next to the pipe so that it doesn't move. With the other hand, slip the second pipe over the exposed part of the rebar and bring the two pipes together as seen in Photo 2.
Then, place your foot on the first pipe and with your hand, pull the end of the second pipe upward to bend the rebar as seen in Photos 3 and 4. Photo 5 shows the bent rebar. Follow this procedure for the remaining rebar.
Step 4: Setting the Tire in Place to Add the Concrete.
With a hoe or shovel create a small mound of dirt as seen in Photo 1. With your gloved hand, pat the mound to compact and smooth the dirt. Remove any large visible rocks or dirt clods.
Then place the tire on the mound (Photo 2) and place a level on the top of the tire. Adjust the tire so that it sits level on the mound as seen in Photo 3. Rotate the level by 90° and adjust the tire so that it is level.
Carefully remove the tire and place a garbage bag or piece of plastic on the mound and then place the tire on top of the plastic, as seen in Photo 4.
Use the level once again to adjust the tire so that it is level in both directions. The plastic-covered mound prevents the concrete from oozing underneath the tire.
Step 5: Creating the Mold for the Concrete Section Above the Tire.
To start this section I will refer you to Photo 1 to show what we are going to build in the next 2 steps. The bottom tire is the permanent mold and is filled with concrete. It becomes part of the concrete pier. The upper tire is the temporary mold which provides support to keep the concrete in place and is later removed after the concrete has cured. In Photo 5 the shadows obscure the lower tire so that only the upper tire is visible. This gives the illusion that we are working with only one tire.
Cut a 10 inch (254 mm) piece of the tar paper and fold it in half lengthwise so that you have a folded piece of tar paper that is 5 inches (127 mm) wide and 40 inches (1m) long. Position the tar paper inside the tire bead with the folded edge down and place a piece of duct tape about 2 inches (50 mm) from the end. Tape the tar paper to the tire, taping the free end of the tape inside the tire as seen in Photo 2.
Continue taping the tar paper to the tire at 3 inch (76 mm) intervals all the way around the tire. When you work your way back to the starting point, place the unsecured tar paper behind the beginning edge of the secured tar paper as seen in Photo 3.
Place a long piece of duct tape over the beginning end of the tar paper so that it is taped to the tar paper behind it as seen in Photo 4. Place the remaining unsecured length of tar paper around and behind the secured tar paper and tape the tar paper together so that you essentially have a tar paper ring. You will need to trim portions of the upper edge of the tar paper ring so that the height of the ring is uniform.
There will likely be bulges in the tar paper ring. To get rid of them use scissors to cut through the inner tar paper, in the bulging area, down to the fold and tape the cut so that the tar paper lies flat.
Note: It is convenient to use tar paper because it doesn't readily stick to the cured concrete and is easy to remove. One could use cut up paper grocery bags instead of tar paper but it would stick to the concrete and would require a piece of plastic film to be added to the inner side of the paper before the concrete is added to the mold.
Now carefully place the second tire on top of the first tire so that the tar paper ring fits inside of the second upper tire. Cut pieces of cardboard to the same height of the tar paper ring, which in this case is 5 inches (127 mm). The cardboard is naturally stiff so roll the cardboard pieces into a roll to pre-form the cardboard into a ring.
The cardboard pieces are not connected to each other but are placed in-between the tar paper ring and the upper tire. This is done to add support behind the tar paper ring. Keep adding layers of the cardboard to fill the space between the tar paper ring and the second tire as seen in Photo 5.
Step 6: Adding the Concrete and Metal Anchor.
Mix the concrete as directed by the instructions printed on the concrete bag. Wearing rubber gloves, shovel the concrete into the tire and using your hands, push the wet concrete into the lower tire, trying to pack concrete into every space inside the lower tire.
Continue filling the lower tire with concrete up to the tire bead. Then insert the "L"-shaped rebar so that the long end is buried horizontally into the wet concrete in the tire below with the upper end of the rebar exposed and vertical as seen in Photo 1. Space the 3 rebar evenly in the concrete.
Add more concrete inside the mold filling it up to the upper edge of the tar paper. Use a spare (unbent) rebar to stab the wet concrete so that any voids or air pockets are eliminated.
Use a trowel or putty knife to smooth the upper surface of the concrete and then insert the metal anchor (Photo 2), working it well into the wet concrete as seen in Photo 3. Smooth the surface once again with the trowel (Photo 4).
Let the concrete dry for a few days before moving it. Cover it with a tarp if the temperature gets below freezing. Give the concrete a sprinkle of water each day if the temperature is really hot.
Once the concrete has cured, remove the upper tire and the cardboard. The tar paper should peel away from the concrete but it will still be attached to the tire so you will need a box knife to cut away the tar paper at the edge of the tire.
Step 7: Moving the Concrete Tire Pier
The cured concrete tire pier is very heavy and will superbly support and anchor your project to the ground. It is somewhat easy for one or two people to move the concrete tire pier to a new location in the yard. Grab the bottom of the concrete tire pier and lift to a vertical position, as seen in Photo 1, and simply roll it to the new location.
Step 8: Concrete As a Design Medium
Concrete is a wonderful design medium as it can be cast into a variety of molds; a tire in this case. It also can be stained during the casting or afterward. For this project the concrete tire piers will be used in an aviary that I am building and will be subjected to bird poop 24/7, so I decided not to beautify them any further. I think they have a simple beauty all their own. But for other projects, like volleyball net supports or patio deck supports, the concrete may be stained and the tire painted to make the pier more attractive. Inlays are possible as are impressions. Concrete is all about the 3rd dimension and playing with that thought can lead to some pretty amazing design opportunities.