from now on we have to get used to that material, relatively exotic, go on to conquer the construction of different components of our cars. Especially those that are likely to lead to a greater lightening of our car. It is normal that these materials begin to be introduced in sports, and high-quality vehicles, to go joining whenever more cars are generalists, for all pockets. The new BMW M4 GTS will have the possibility of mounting wheels of carbon fiber, entering a select club of sports who have turned to this option. But did you know that in the 70’s you could buy a Citroen with wheels carbon fiber?
Citroën was looking for lighter wheels to make the SM for a suitable car for rally races, and found them in your partner Michelin. These tires would be marketed as an option on the Citroën SM of the street.
The history of Citroën offers us examples of really interesting technological advances that would get the mark of the chevrones reached a level of sophistication that they would have wanted to many competing brands. The most commonly quoted example is that of the suspensions hidroneumáticas. But in this case, it was not exactly Citroën, but his partner, Michelin, who led a project to create these wheels are extremely lightweight, made of a composite material based on carbon fiber.
And as you may have imagined, the motivation that led this company was no other than that of achieving the maximum lightening to secure the aspirations of Citroën in the competition.
These tires weighed half that of a steel wheel, and its appearance was very similar to that of an alloy rim.
With the intention of making the Citroën SM, a coupe suitable for rallies, the chief engineer of the project, Jacques Né, searching for alternatives to the original tires on steel employed in the SM. We assessed the possibility of using some alloy wheels light of an Italian supplier, but Citroën felt that they were not adequate (probably due to resistance problems) to the demands of a rally, as has this great article from Hemmings.
it Was then when Citroën turned to his partner, Michelin, who under the racing department headed by Pierre Dupasquiere, it was proposed to create the Michelin RR “roues resin”, the wheels of resin in the Michelin guide. Though its appearance outside of a tire of conventional alloy, it was built with reinforced polymer, carbon (in reality it is a resin-based carbon that was created with a process similar to fiberglass) that made them extremely lightweight, at around 4.3 kilograms. These tires still had a central piece of steel, on which it was screwed, as we can see in the image below published by Jalopnik.
The SM debuted with carbon rims with a victory in the Morocco Rally of 1971, and even offer as an option on the Citroën SM of the street, in a coupe as a revolutionary, and a work of the art deco French. Today they have become a piece almost as a collector, and in one of the spare parts more expensive for those who treasure one of these cars.