Article By Chris Callen Photos By: Heather Callen
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ast month we picked up on part 2 of our Science of Tires segment where we visited the world headquarters of Metzeler Tires. As usual when I get to do something cool, we had to cut it into another part so we are picking up as we headed into the Dynamic Testing area of their labs. The Dynamic Test Department: In contrast to that indoor procedure, on the outdoor track, they have a live action test where they test both wet and dry conditions. On the wet, they have a glass area where a motorcycle passes over cameras underneath. The glass area is covered in a solution of milk and water, and an image of the contact patch is captured as it passes. By increasing the speed, they can change the dynamics of the testing. On the other side of this area, they also provide feedback for dry conditions in a similar manner. As the motorcycle passes, it goes over a computerized mat that reads the contact patch and transfers the image to the computer screen. In the same way, they change the dynamics by varying the speed at which it passes. In all of these
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June ‘18 - CYCLE SOURCE MAGAZINE
outdoor tests, they are factoring in a lot of parameters. Obviously, the weight of the machine and the weight of the rider are the first two. The results of these tests provide a molecular look at how the tires composition and design are utilized. The idea of this testing is to identify the ideal balance of pressure, load, contact patch shape and uniformity. This is an important place to talk about chopper guys and the age-old practice of running a tire at low pressure to give extra suspension. You see, tires today are not made the same way and manufacturers are doing all this testing and research to know how a tires sidewall and contact patch will stand up under a known weight at a known pressure. When you run a modern tire at a lower than suggested pressure you violate the structural integrity of how the tire was made. It becomes an incredibly dangerous proposition in handling, longevity; the whole deal goes out the window. In the old days tires were basically balloons with tread glued to them; you could do whatever to them and very little changed. Today you are better off running within
the manufacturer’s suggested range and taking advantage of their all that their scientific testing provides you. You see. In contrast to car tires, a motorcycle tire is very lightweight in structure so much smaller amounts of influence can affect how they displace pressure. The amount of inflation, the amount of weight, the rim width, all are factors that must be kept in close arrangement to what the manufacturer suggests. If not, failure of the tire will result, one way or another. While the Static Department has to deal with modeling to predict how a tire will react to different road surfaces, the Dynamic track environment has several different asphalt patches that put those models to a real-world testing, and that’s just at the Vizzola test track. Metzeler has many tracks where they test real conditions from all over the world (where they gather this information??). It would be nearly impossible to build a track that would give you all the conditions you needed and if you did, the waiting list to get on it would be ridiculous. While all this testing is going on, the
