Re-using Old Tyres

A great use of old tyres. Sitting on them should be all right but would you grow veggies in them?

It wasn’t too long ago most car tyres ended up on bonfires in autumn.  Now though there are tighter controls and a bit more understanding about just how polluting they can be.  Finding new and interesting things to do with them can be entertaining and more and more people are being really inventive when it comes to reusing them.  There are lots of play parks around that have soft surfaces made from the ground up rubber after the steel wire has been taken out and we probably sit on them as the new park benches have old tyres mixed in with old plastic carried bags.

Other uses are:

·         Roof tiles

·         Road surfaces (the quiet type)

·         Children’s swings (cut to look like swans)

·         Earth ship houses with rammed earth inside them as walls.

·         Growing flowers

·         Keeping down the silage sheets

·         Rolling down hills

·         Making sandals and furniture

The biggest discussion though is whether it’s a good idea to use them for growing vegetables.  The dark colour absorbs heat, the drainage is good and they are ideal to stack up for when you want to grow spuds, strawberries or tomatoes. They can also be used effectively on steep banks to stop soil erosion.

Under the EU Landfill Directive introduced a few years ago, tyres have been classified as hazardous waste, with a ban on whole tyres being sent to landfill.  So do tyres leach out toxins which are taken up by the plant to end up on our plates or is it just bureaucracy gone mad?

A few tyre-ing facts

Tyres are extremely durable. During manufacture, natural rubber is combined with synthetic rubber and treated with a cocktail of chemicals, some toxic or known carcinogens, others more innocuous, to make the tyre withstand all the forces that will act upon it on the road. 

The forces that tyres have to resist on the road are: sunlight, water, acidity, abrasion and friction with the road surface. Each of these forces works in a different way on the tyre, but over time all break it back down into its constituent parts.

During this process, the various chemicals and compounds are slowly released through ‘off-gassing’, particulate matter or 'tyre dust', or as chemicals, leaching out into water. Every tyre loses about 20% of its weight during its lifetime on the road, getting slowly ground down and blowing away in the wind.

Tyres and toxins

Most off-gassing occurs within the first year, for example, that 'new carpet smell', and given that tyres typically are 3 to 5 years old before being discarded, this would not really seem to be an issue.

What should be of greater concern to vegetable growers, is the gradual erosion through water and sunlight, and any leeching of chemicals and toxins that may occur to contaminate the surrounding soil, water and anything grown in it.

What happens when tyres degrade

The disintegration of tyres is well demonstrated when they are used to weigh down covering sheets in silage areas. The tyres usually degrade to point where the steel belt starts coming out of the tyres after ten years.

Yet the effects aren't completely understood. A report by the Environment Agency states that "little is known about the long-term leaching of organic chemicals from tyres in landfill sites.”

Like many types of rubbish we produce today, we don't really know what the individual effects of the leaching chemicals are. However, there are strict controls in place for the proper disposal and handling of used tyres, and it is illegal to dump them, with large fines for fly–tipping - showing that problems with tyre disposal are appreciated.

Risky Business?

Mischa Hewitt is the author of Earthships in Europe and runs Self Building an Earthship training courses in Brighton found a long list of toxic chemicals in the tyres and wonders if it’s worth growing edibles in them. “When it comes to growing food in tyres, why take the risk? Whilst the quantity of toxic chemicals maybe small, we don't know the exact amount used in tyres because of commercial secrecy.

People generally grow food organically for themselves to avoid exposure to synthetic chemicals. It seems ironic that a 'Permaculture way' of reusing tyres could be unintentionally reintroducing potentially harmful chemicals back into the equation.” 

Even lining the tyres with polythene before the soil is put in doesn’t seem to attractive now.