Yokohama invents tire fins to reduce drag and lift

The flow patterns for an aerodynamic tire with Yokohama’s new fins. Credit: Yokohama

Yokohama invents tire fins to reduce drag and lift.

Half a century ago all the coolest cars had fins, like the Cadillac Eldorado, the Chrysler Imperial or the Dodge Super. But while the cars of the 1960s often had fins, the tires have always been conspicuously fin-free.

That is until this month, at least, when Yokohama announced it had discovered adding fins to tires reduced drag and lift on a moving vehicle. The new technology could lead to the development of tires that will improve fuel efficiency and vehicle safety.

The Tokyo-based manufacturer has been closely studying tire aerodynamics, looking into technologies to control the airflow around tires in motion. In 2012 the company discovered placing fin-shaped protuberances on the inner sidewall of the tire in a radial or spoke-like pattern reduced the aerodynamic drag inside the wheel wells.

But the latest discovery seeks to control aerodynamic flow throughout the vehicle body by using a new fin shape and placement technique that places the fin protuberances at angles near the tire’s shoulder.

The fins on the tire’s outer sidewall help to reduce drag on the upper part of the tire during rotation, while suppressing lift when on the lower part of the tire.

Yokohama says the large-scale study that discovered the fins’ ability to reduce lift and drag was conducted on a special Supercomputer used by experts at Tohoku University. It allowed them to run aerodynamic simulations at different parameter values to work out the optimal placement of the fins on the tire surface for the best aerodynamic result.

Yokohama’s research results have lead them to create a number of new tire designs they believe will contribute to vehicle fuel efficiency, including a “dimple” design that places small depressions on the side of the tire. The latest breakthrough will allow the company’s tire designers to work out the optimal placement and shape of those dimples and any fins.

Sure, the tire fins might be far more subtle and nowhere near as cool as the fins on the bodywork of those 1960s machines we all admire, but if Yokohama can prove they reduce drag and improve fuel efficiency, we might all have to get used to seeing fins on the road again.

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