At Michelin’s Tyre Test Centre at Clermont-Ferrand we had the opportunity of testing the new XAS and XN radial tyres.
They are an extension of the “X” construction but with the XAS Michelin has not only distinguished between the functions of the tread and the casing of the tyre but also taken into consideration the fact that either edge of the tread and the corresponding tyre wall will act differently according to whether they face outwards or inwards on the car. Hence the asymmetric tread pattern which varies from a closed ribbed, heavy shoulder on the outer edge to widely spaced tread blocks on the inner. The result is said to be an outstanding tyre for high-performance cars.
The Michelin XN tyre is a go anywhere, “go anything” tyre; it is a radially constructed tyre with a steel braced tread and a really rugged tread pattern.
The S-bend of Michelin’s comprehensive and imaginative Test Track incorporates the specially laid-out “Mercedes Curve” where cornering speeds up to 150 miles per hour are possible. A Mini Cooper S certainly put the XAS tyre through its paces for us. There was no tyre squeal at reasonable speeds even when negotiating the acute S- and U-bends on the Vehicle Handling Circuit, and the usual Michelin “X” thump when passing over changes of surface, of which there were concrete, tarmac, pave, etc., has been eliminated. The track was specially sprayed with water to demonstrate the extremely good road-holding of the XAS lyre.
Although Michelin XAS tyres cost 15% more than other radial ones, and these are 25`%, more expensive than the cross-ply tyres, they will, it is claimed, last twice the mileage of the latter and give a significant mileage improvement over other Michelin types even when used continuously at high speeds, while their performance is not affected by normal wear.
These XAS tyres are a departure from convention and Michelin’s Research Department is to be congratulated on its courage in producing such a revolutionary tyre. They had such confidence in their new product that they flew out a party of British journalists to France in a B.U.A. Viscount to try it out for themselves.