I do not like using car tyres in the garden. I agree they are not aesthetic and they may be a source of pollution if kept long enough until the rubber degrades. However a tyre full of soil in your garden is probably less harmful than the rubber dust blowing in off the road outside. Tons of rubber are worn off tyres every day, that's why millions are replaced every year. The dust then blows around until it is washed into the soil or drains. Ironically one of the main pollutants from tyre rubber is Zinc which is also the trace element often found in short supply in agrochemically worked soils.
For years I have seen gardeners using them where another container would have been too expensive or too stealable! I have seen them on allotments for growing potatoes or blanching rhubarb and many as dent proof 'vases' outside garages. I have seen them in use for years in all sorts of places, especially in poorer areas and countries. Car tyres come free! As many as you want, often even delivered for free. And if we can find uses for them they do not get added to the tyre mountain and we free other resources.
Now there are several drawbacks to tyres. The first is their appearance. This can be radically improved by turning them inside out, which I'll explain how to do easily in a bit. The next is that they are inefficient to use in many ways because of their awkward form. One of the best and commonest solutions I've seen involves cutting out just one side and reversing the tyre. This is then stood on a wheel to become the 'vase' used by garages. This makes all the inner volume of the tyre available and open, and if stood on a wheel this fills the middle and even comes with drainage holes.
Without the wheel and set on the ground such a funnel shaped reversed tyre is very handy for growing plants such as courgettes. The entire area is open to catch the rain funnelled to the middle and the rubber sidewall base acts as a mulch retaining the moisture in the soil and suppressing weeds. What is more the reversing changes the shape so the sidewall sits flat and does not trap a pool of water to encourage mosquitoes. A pane of glass set atop a funnel tyre makes it into a very handy coldframe so the courgette can be planted out weeks earlier. Even without the lid the tyre walls protect the plants within from wind and many crawling pests. After all why should a slug travel all the way up and over a barren hostile terrain. Thus tyre coldframes are also particularly useful for French beans, lettuce and Chinese cabbage.
It is also easy to fasten a piece of netting over the top rim and thus make a completely pest free zone excluding the adults of pests such as cabbage, carrot and onion flies and cabbage white butterflies, as well as the slugs and snails.
It is also easy to make them deeper by stacking them. First you cut another tyre of the same size, but with both sides cut out. If this is done with one side cut a third way down the sidewall and the other near the shoulder then when reversed one lip turns in and one out on a hollow neat looking rubber cylinder. This will now sit comfortably in or on the funnel tyre. And another can sit on that. The glass pane, plastic sheet or netting cover can go on the topmost tier and you have a large sheltered environment. Of course it is only lit from above but one or two deep are perfectly bright, the deeper stacks are more for frost protection or blanching cardoons. And it is not essential that the bottom tyre is a funnel, it can have both sides cut out to make more floor space available but does become less stable if it then has to support a stack of several.
It is fairly easy to stack tyre cylinders up to four, five or six high if they are well matched. A stack of hollow tyre cylinders is really good for forcing rhubarb and seakale as it stays warmer and drier than the traditional bottomless metal oil drum or dustbin. They also make a tall frost proof house that can be put over and taken off a large plant in minutes. For example a tomato plant tied to a cane can be given a protective tyre cover at night, the topmost tiers and lid removing on cold windy days and all except the bottom on fine. This way I found I could put plants out weeks earlier.
But most importantly I found the stackability of reversed tyres meant I could make large planters for free for some of my biggest plants. I wanted to grow tropical crops in my double polytunnel and I wanted BIG containers, the plants are warmer in these up out of the ground in the warmer air. And when the sun shines the roots get warmer still. For example the pineapples in particular wanted plenty of room. I could give them enormous containers full of compost with perfect drainage at the bottom. And the thick rubber walls may warm up in the sun but they do not vary in temperature very rapidly as they have a lot of thermal mass. So lots more tyres line the back wall to be a set of staging supports and also add more thermal mass.
I'm sure many of you will have seen car tyres stacked as low walls around motor racing circuits. That gave me an idea and I tried erecting south facing semi-circular tyre walls around young peach trees in my orchard. The walls were started off with the biggest toughest tyres at the bottom with each layer made of progressively smaller tyres overlapping the lower ones. I leave gaps between the tyres so that they overlap symmetrically as they balance better. I made each layer from less tyres so that the ends were chamfered. As the trees grew the walls were rebuilt further away from the trunk and higher. Once the trees were cropping it was immediately obvious that those that had tyre walls were setting more fruit more often. Over the years I have consistently found the extra warmth and shelter afforded has more than repaid my building the walls.
Then I had the idea of tying tyres in rings in a circular wall over twelve feet across but only waist high. By putting a plastic liner in this I made a storage tank that holds all the water from my gutters. I would never have found as many water butts to do the same job. (Most of the force is at ground level so the bottom rings must be well tied. Further up there is less pressure. It is also a good idea to line the lot with cardboard, old carpet and old plastic sheet first to prevent any stones or sharp edges piercing the bottom of the plastic liner.
I've even used tyres as retaining walls for my herb bed. I stacked a double row of unaltered tyres and simply tied them together and fixed them down as I went. These were rigid enough so that I could back fill against them with earth to give me my sloping south face to grow on without using expensive supports to make a conventional back wall. Of course tyres were also used to bulk out the soil infill initially as well and this also reduced the loading in the double wall. The wall was covered with old carpet upside down which soon went green and is out of sight behind the herbs anyway. One side was also retained with a sloping tyre wall filled with soil and planted with thymes which soon covered the supports.
And yet another use was when I made a south facing vertically faced tyre wall filled with compost. I grew strawberries in the pockets formed and it gave wonderful crops very early on the sunny side. There could have been a late crop on the shady side if it had not backed onto a hen run full of Marans!
Even the cut out rings are useful. I find them ideal for holding down plastic and newspaper mulches, and to stop covers sliding off my compost bins. Two of them wired together either side of a sheet of clear plastic make a good lid to fit on top of an inverted funnel tyre. This combination also makes a very snug neat house for over wintering dormant tender plants such as fuchsias or as a temporary cloche in spring.
Indeed there seems no end to the uses tyres can be put to. I've seen and been sent photos from all over the world of tyres turned into useful objects. From swings to flower displays, sandals, swans and even chairs. See what your ingenuity can come up with, and if you don't like it, well it was going to be thrown away anyway. In the USA they have been cut mechanically in half into two c shapes, thousands of these are buried side by side, hollow side up, under whole areas of golf courses where they act as water reservoirs a couple of feet down. Beat that.
How to cut and turn tyres.
Tyres cannot be cut easily in their tread or rim but the sidewalls are easy. Rubber cuts easier when wet, so use a sharp knife wet often, and pull it up out of the rubber rather than push it into the cut. Once you find how easy sidewalls cut you will be more careful avoiding kerbs! Turning a tyre inside out is probably impossible. With one side cut out it is possible to peel it over the other way without a lot of force, the more worn ones are easiest. With both sides cut out any tyre will flip easily. The only skill is cutting them where they turn the most convenient shape; it is therefore sensible to cut further away from the tread than closer to it as you can always pare a bit more off later. eat.