April 2008: Eyes shut through the steep bend

As he flies through the steep bends in the C-class, Angelo Pérez Riemer coolly and calmly.discusses wheel loads and lateral acceleration as though giving a PowerPoint presentation to a group of dealers about the benefits of good tyres. In reality, the Continental employee sits behind the steering wheel of a silver saloon car, racing around the large oval circuit on the Contidrom test track at over 200 kph. The steep bends allow the car to race through the curves without any lateral force, meaning, in principle, that a driver could take his hands off the wheel at top speed without coming off the track. But now would not be a good time for this, despite the reliable ContiSportContact 3 tyres the car is driving on. “Just for your information”, Pérez Riemer explains, “we’ve now reached 2 G”. Speeding around a race track at twice the force of gravity in a standard commercial car is certainly not for the faint hearted. When driving through the steep bends, you need all your concentration just to make sure your stomach doesn’t get left behind. The car is eating up the grey, banked asphalt track. The blue band of sky, the surrounding coniferous trees – everything passes in a blur.

For test driver Angelo Pérez Riemer, this drive around the oval circuit is just one of the many tests he has to complete for hours on end on a daily basis without ever becoming green around the gills. The 34-year-old, German-born tyre tester with Spanish parentage is a team leader at Continental, for whom his grandmother also once worked, and is responsible for subjective tyre testing, a job which, instead of using measuring instruments, requires the drivers’ subjective impressions (or their ‘bumometer’ as they jokingly call it in the paddock). It is only as a result of finely tuned sensory perception and years of experience behind the wheel of test vehicles that permits Pérez Riemer and his colleagues to obtain objectively useful test results from their subjective impressions. How does a tyre behave if you quickly change lane? What about when braking on a wet road surface? What noise does the rubber make when driving at high speeds? These are the kind of questions tyre testers have to answer to be able to thoroughly evaluate a tyre’s performance. The tyres are also subjected to comprehensive objective test series using instruments which evaluate the handling, braking, driving noise and aquaplaning properties of the tyres, for instance.

The Contidrom’s large high-speed oval circuit, a 2.8 kilometre circuit with a maximum 58 degree bank is only one of many test tracks on which a tyre must prove itself before receiving official approval for road use after undergoing approximately two to three years in development. However, the tests performed on the high-speed track are crucial in assessing a tyre’s performance. This is because the physical forces affecting a tyre change when travelling at high speeds. For instance, when stationary, a tyre is subject to loads of approximately 250 kilograms whereas at 160 kph, this drops to only 30 kilograms. The aerodynamics causes the vehicle to lift from the ground, causing drag, explains Pérez Riemer, using the technical term. “The impression you get whilst driving is then quite different to that at low speeds.” A tyre with speed index V, permitted for speeds of up to 240 kph, is of course pushed to its limits. Pérez Riemer explains; “A tyre must be capable of being properly controlled even when driven to its limit and in critical driving situations. Like now for instance”, he adds, suddenly yanking the steering wheel to the right as we speed down the straight at 180 kph, simulating an abrupt motorway evasion manoeuvre. In the passenger seat, my pulse races and I break out in a sweat – but the vehicle straightens up. “Do you see?” asks my driver, “a good tyre has to be able to cope with that”.

Every Continental tyre is put through a rigorous programme of testing on the various different test circuits at the 160 hectare Contidrom – one of the most state-of-the-art test tracks in the world, situated 35 kilometres north east of Hanover. The track is also used by automobile associations, the TÜV certification body, car magazines and all famous car manufacturers, to test ESC calibration in addition to tyres. The wet braking track, for instance, is used for testing tyre braking in wet conditions on a number of different road surfaces, including asphalt, concrete and brick. The aquaplaning area features a track system with rails to investigate the speeds at which a tyre aquaplanes. The approximately four kilometer-long handling track is used to determine how a tyre handles when pushed to the limit.

“Pérez drives the dry handling track” – the Contidrom tower has given test driver Angelo Pérez Riemer the green light to use the dry handling track. Over the next 15 minutes, the tyres screech so loudly that you could record perfect sound files for a Hollywood car chase. From the driver’s seat, the talk is of steering wheel angles, vehicle responses and perfect delays and you get a sense of just how demanding the job of a tyre tester really is, and the forces to which man and machine are exposed when a black tyre is being tested to its very limits. A tester drives up to 400 km per day, with every test kilometre equivalent to around ten kilometres of normal driving conditions for tyre and vehicle. All test vehicles have to be taken out of service after approximately 50,000 kilometres.

In addition to the Contidrom, Continental uses around 20 additional test tracks around the world to test its tyres. Depending on the type of product (summer, winter or off-road tyres) and their eventual market purpose, the tyres are put through their paces on the Nürburgring, gravel tracks in Uvalde, Texas, a sandy beach in Römö, Denmark, snowy alpine passes in Austria, and icy tracks in New Zealand, the Swedish Arctic Circle or even an ice rink in order to obtain official approval for road use. Original equipment manufacturer clients of Continental, such as Audi, BMW, Mercedes Benz, Porsche or Volkswagen, also tend to have highly specific demands for their tyres. For instance, some are particularly concerned with excellent handling properties, whereas others are more interested in comfort or wet grip. Every test has performance specifications which list all the required aspects which the tyre manufacturer has to fulfil in the design of a new product and which are then rigorously tested. Continental employs approximately 120 test drivers around the world.

One of these drivers is currently taking another spin around the oval track at the Contidrom and explains how the steering movements are transferred to the road through the tyre and how that should feel to a test driver. “The key factor is how the vehicle responds when steered – whether the lateral acceleration is clear, precise and square or too soft”, Pérez Riemer explains. The silver Mercedes again speeds out of one of the steep bends at 200 kph. “I know precisely what the vehicle is telling me through the slightest delay in response”, he adds as the countryside flies by. “In theory, I could shut my eyes right now and would know exactly what the vehicle was about to do.” Please don’t …

Contact:

Alexander Lührs

Head of PR – PLT Tyres

Continental AG

Büttnerstraße 25 , 30165 Hanover, Germany

Phone: +49 511 938 2615

Fax: +49 511 938 2455

E-mail: alexander.luehrs@conti.de

Internet: www.conti-online.com

Image database: http://mediacenter.conti-online.com