Run-Flat Mousse – Victim of its Own Success
As we reach the mid-season break in this year’s FIA World Rally Championship, it is worth pausing to remember a small and seldom celebrated development that for two decades has kept competitors in the action and even seen drivers take first place when disaster would otherwise have loomed large. This saviour of many a racing team’s competition hopes is the mousse insert, an innovation that can keep a tyre in roadworthy condition even after receiving substantial damage.
It is twenty years since the Michelin Group first publicly showed off this mousse insert, which it christened the ATS (Appui Temporaire Souple, or Flexible Temporary Support), at the gruelling 1987 Acropolis Rally. Initially the system had its limitations, with post-puncture use restricted to a maximum of 30 kilometres and centrifugal force caused by the moving mousse ring creating unpleasant steering wheel vibrations, but despite these teething troubles, numerous improvements were made in subsequent years and today the system is said to enable vehicles to keep driving on 90 per cent of all punctures.