There are only two physical requirements for a car tire tread pattern.
It must provide traction for acceleration and braking and it must move surface water out of the way so that the tire can touch a wet road without aquaplaning, which is where a vehicle slides uncontrollably on a wet surface.
A simple block pattern is great for off-road traction, but the front and back of each block wears quickly on tarmac. Circumferential ribs, edged with tooth-like indentations, give extra traction without increasing the overall wear.
Regularly spaced cross-tire features, however, generate a loud noise so irregular patterns are used.
At 60 miles per hour in moderate rain, a car tire has to displace five liters of water every second just to maintain contact with the road. Crosswise cuts in the tire lift water off the road, which is then squirted out sideways through tunnels in the side ribs.
With motorcycle tires, the oval cross-section of the tread cuts naturally through water, so aquaplaning is rarely a problem, and noise levels for the rider are hardly an issue given all the other noise. All that is needed is traction.
It is clear that these requirements can be fulfilled by many different patterns. In fact, most variations in tread design are decided by the tire makers’ marketing people.
In the late 1980s, work was done on three-dimensional CAD/CAM design software for a top tire manufacturer.
The software allowed the designers to create almost life-like pictures of tires based on two-dimensional drawings of the tire section and the treads.
The designers agreed that this saved them a lot of time, because many of the hundreds of designs they produced every year were turned down by the marketing department, purely because of their appearance. Tread patterns were described as “not sexy enough” or “not masculine enough” and were sent back to the drawing board.
Only when the marketing department agreed with the general look of the tire and its tread pattern could a set of test tires be produced. These were cut by hand, because of the high cost of a mold, and then tested.
Experienced tire designers knew what made a certain tread pattern perform well for a given type of tire and could therefore deliver surprisingly new and different designs again and again that satisfied the marketing department’s desire for new products but also still behaved well during the tests.
