In 1988, 209.5 million car tyres, 42.7 million truck tyres and 19 million road tyres were produced in the USA alone. Over 320 million were sold in Japan, France, West Germany and the UK Of all these tyres, only 30 percent are re-treaded, the bulk of the remainder are dumped. There disposal is very problematic. Heated in the absence of oxygen, tyres produce vast quantities of oil, more than a gallon rep tyre, accompanied by thick black smoke. Dump fires are extremely polluting.
Car dumps themselves cause local pollution with high concentrations of lead, cadium and zinc.
Their sulfuric acid contents represent a substantial environmental threat. New roads need materials for construction, take land previously devoted to amenity use, or food production, fragment the countryside and increase traffic and development areas over a wider region. Most roads consist of sand, gravel and rock with a tarmac surface. Each mile of UK motorway uses 250,000 tonnes of sand and gravel. Covering more land with concrete prevents water from seeping into the ground and may cause flooding.