Car Tyre foundation, a great way to build strong sturdy pillars, reusing a waste material & without concrete.
The technique goes a bit like this;
Items needed: Lump hammer, crowbar, plank of wood (same width as tyre), level, pair of gloves.
Level ground where you’re going to place your 1st tyre, and lay a thin bed of pea gravel. Place the tyre on the gravel and ensure it is level using a spirit level (2 foot level seems to work well). Fill the tyre up to the 1st lip where the tyre would have joined the rim. With your fingers jab the gravel under the lip until all the gaps are filled. Fill the remainder of the tyre up until the second lip, and heap up a bit of excess gravel. With the help of a friend, twist / lift up the lip / edge of the tyre and jab as much pea gravel in as possible, working your way around. The more you can jab in now the easier it will be later. Now rest you wood on top of the tyre, so you have a solid platform on which to rest your crowbar. Wedge your crowbar under the edge of the tyre and stuff gravel until you can fit no more. Now hammer the gravel into the side of the tyre, topping up with gravel as required. Repeat this around the tyre, until when you try to squish down the rubber edge of the tyre with a finger there is no movement (I found it took going around about 2 or 3 times before it was solid). Once solid, check your levels of the tyre working your way around like a clock face. If you find low points, lift up the tyre rim with your crowbar and pack with more gravel using your lump hammer. Until the level is right. Never take gravel out of high points, only fill in low points. We estimated that whilst learning it took between 30mins to 1 hr per tyre.
Place the next tyre on top of your 1st centrally & repeat the steps (If not central, more work needs to me done at the levelling stage).
It is worth noting that each tyre will be approximately 30mm higher when filled, compared to an empty tyre.
We use 10-20mm pea gravel in the tyres, as it can be compacted enough to give us the structural stability needed. But the gaps in-between the gravel are big enough for an excess water to drain down. But small enough that water can’t ‘wick’ up. By carefully thinking about materials we are using, we can avoid the necessity of a DCP (damp proof course, used in brick work to prevent water ‘wicking’ up), this means fewer polyurethane products are needed. Which is better for the global environment and helps the budget! Generally speaking you try to avoid any materials that would prevent the straw bales / natural materials from ‘breathing’. So if you’re in a situation where you want to use a DPC, it’s probably best to go back to the drawing board!
Please note when picking up tyres from your local establishment, lorry rims make rather good fire pits!
Please see below a very handy time lapse courtesy of Jeffery the natural builder