Jermaine Ammeil, who owns the Rev Tyre Tech (RTT) franchise in East London, has a powerful method of demonstrating the reliability of his product, a tyre sealer that is guaranteed to keep a tyre inflated. He takes a large screwdriver and, with a hammer, whacks it into the tread of his delivery vehicle’s front tyre, wiggles it about and then slowly withdraws it, without any loss of pressure.