50 years of MICHELIN PLR ”Mille Pattes”: the somewhat different truck tyre tester
- Top speed tests with two engines and on ten wheels
- Extra long, extra wide, extra strong and heavy
What do you do with a nine-tonne vehicle with ten wheels and two powerful V8 engines? Sure, test tyres under extreme conditions. In the early 1970s, cars and trucks became faster and more powerful. Michelin therefore had to adapt its tyres to the new performance requirements – and of course test them before production. Thus, the “Mille Pattes“ (centipede) was created in 1972 to test new truck and also bus tyres at top speed. Because Michelin was a shareholder of Citroën at the time, the test vehicle was based on a Citroën DS station wagon.
In the rear of the “Mille Pattes“ sat two V8 Chevrolet engines, each with a capacity of 5.7 litres and 250 hp. One engine was responsible for driving the test vehicle, the other for an additional drive for the test tyre mounted in the middle of the vehicle. This was fit on a swing arm and could be hydraulically lowered and adjusted to different angles during the test drive. This allowed the engineers to adjust not only the speed and braking, but also the load and drift of the central wheel to test the tyre in every sort of conditions. A hydraulic cylinder was used to apply loads of up to 3,500 kg. Sensors recorded data, which was then analysed in the laboratory. In the early 1980s, the Mille Pattes was replaced by other test equipment – but to this day it remains an icon of Michelin innovation. Today, the centipede stands in the Michelin Museum in Clermont-Ferrand.
Technical data of the "Mille pattes"
Engines: Two rear-mounted Chevrolet V8 engines (5.7 litres), each producing 250 hp at 4,800 rpm. Engine cooling via two 14-litre radiators with four fans.
Dimensions: Length: 7.27 metres, Width: 2.45 metres, Height: 1.56 metres, Ground clearance: 0.21 metres
Weight: 9,150 kilograms with equipment
Performance: Top speed 180 km/h, speed on the test track: 155 km/h
Power transmission: Rear-wheel drive with three rear axles from the Peugeot 504. GM automatic transmission with three gears, Michelin gearbox of own manufacture.
Body: Braced and welded longitudinal profiles in U-shape (240x80), chassis, body structure and doors made of sheet metal, movable side body parts, radiator bonnet made of aluminium, all joints welded.
Suspension: Independent suspension, hydro-pneumatic with one spring ball and one cylinder per wheel and four spring balls for the central test wheel.
Steering: DS type power steering with double wishbones
Brakes: Citroen DS disc brakes and calipers, Citroen HY drum brakes and wheel hubs.
Tyres: 205/55 R 16 on all ten wheels of type HY (tyre pressure front/rear: 2.8/3.0 bar), central test tyres in different dimensions from 8 R 22.5 to 12 R 22.5
Year of manufacture: 1972, single copy without registration