Tire-Pounding for Beginners

At the Earthship Academy in Taos, NM they teach how to use tires effectively and safely in wall structures, in theory and practice. Since Earthships consist of a lot more than tire-walls, I won’t be taking away anything from this comprehensive course if I wrap up the basics in this short post.

Tires are frequently used, especially around here, but not always in the safest way. The results, both pics are from not too far from where we’re building, range from tolerable to frighteningly dangerous. Though the basics of building a decent tire-wall are not too hard to explain.

Come Prepared

You don’t need a lot of equipment for pounding tires, but a few items are vital. Good boots is where it all starts, as they are just as effective tools for their part of work, as the sledgehammer is. Also, if your hands are used to the keyboard and coffee-mug as mine, gloves are lifesavers. I personally recommend bicycle-gloves, which protect your palms. Wrap-around sunglasses (with protective lenses) are useful not so much because they shade from the sun, but because they keep the dirt out of your eyes, which will be flying even if you try pounding “carefully”. Other than that, you’ll be sweating a lot, so in terms of clothes, less is usually more.

The Tools You Need

The sledgehammer is of course the most stereotypical tool for pounding. But to get the dirt into the tires you’ll need a shovel, and probably even a bucket at some point. The level and tape-measure are important for positioning and leveling, and the pick and crowbar help a lot if you have to re-position a tire that’s already been filled. This is what we try to avoid, but it does happen a lot.

Choosing the Right Tires

Tires come in all sizes, indicated on their side. What’s most interesting for using them in walls is their width, which could be 195, 205, 215, 225, 235, etc. millimeters. Obviously, the bigger ones should go on the bottom, to carry the smaller ones, and a course should have tires of the same sizes to create a flat, level surface to build the next course on.

Positioning the Tire

Once you got your right sized tires, you lay them flat on the ground. But not just about anywhere! They should be in a straight line, which is frustratingly difficult to judge by the eye. So setting a string at exactly where the wall should end is essential. Also, keep in mind that the wall will not be plumb – it cannot be for its nature. Instead, it should slope back uniformly, by placing each course 4 cm (an inch and a half) further back. This calls for lots of backfill on the other side.

Lining the Tire

After so much planning and calculation, you might think that we’re ready to start using the sledgehammer, but there are a few more steps to be taken: The dirt will pour out of the tire if we don’t line the bottom with something. Cardboard is ideal for this, as they are just as universally available in the world as used tires. A good three-to-five layers of cardboard is needed… even this might blow on occasion if the pounding gets very intense. Now, finally we can get down to the dirt part.

Filling the Tire

You’ll need dirt and lots of it! Depending on its size, a tire can swallow up a good five buckets of dirt or more, so it’s good to have a huge pile not too far from where you’ll be pounding. The type of dirt doesn’t matter, it can be full of rocks, sticky clay, or mostly sand, as in my current case. It should not be very wet though, and organic materials such as sticks, leaves, etc. are better left out.

Before pounding the living daylights out of it, we can make it easy on ourselves, and simply push the dirt into the huge pocket the tire forms all around by its very nature. This can be done by hand first, in the second round it may be easier to lift up the edge with the pick or the sledgehammer and kick the dirt in with your boots.

Once you’ve reached the third or fourth bucket of dirt, the tire will be quite full already… or so it may seem. Once you’ve given it a good pounding, it’ll look half-empty again. When pounding a tire, you don’t want to hit the rubber itself. You’ll notice when it happens, bringing the compacted dirt out towards the center again. Instead, you pound the dirt in the middle diagonally towards the inside. After a while you notice the edges expand and get firmer with each hit. This is exactly what you’re aiming for.

Leveling the Tire

And now, on to the precision work: A tire is not completed until it is completely hard on all sides, something you can check by giving it a kick with you good boots. They should not have the smallest give. Also, the tire should be level, not sloping towards either side, while being level with its neighboring tires. If part of a tire must be brought up, it can be pounded more on that side. The rubber will expand, and be even firmer in the process. If the gap is large, and simple pounding won’t do, you can lift up the inside edge of the tire, or even the entire from the outside, while the sledgehammer pounds down on that part. This can be done by one person, though it’s more comfortable (not to mention safer) with two.

All You Need to Get Started

So this should be enough theory for trying tire-pounding in practice. I suggest to experiment with a small project at first, such a garden bench or a small wall. If you find a liking to it, you’ll be glad to know that this construction method will give you a very thick (thremic) wall, safe from fires, floods, earthquakes, and radiation. Of course, it will have to be covered properly with concrete or clay plaster, to avoid off-gassing. And not lastly, they are fun to build, giving you a decent work-out. However, as this is was my first week of physical activity in a year, the picture of me looks more like wear-out.