Yokohama unveils drag-reducing ‘tyre fin’ technology

Achieving maximum aerodynamic efficiency is always good, right? Not necessarily so. Sometimes being a drag isn’t such a bad thing, as Yokohama Rubber has discovered. The Japanese manufacturer shares that it has developed a tyre that increases a car’s aerodynamic qualities – by making those of the tyres worse.

On a car fitted with standard tyres, air flows turbulently within the wheel wells as the car drives along, and some of this air flows out alongside the vehicle and causes aerodynamic drag to worsen. The tyre Yokohama has designed utilises fins to lower vehicle aerodynamic drag by improving the flow of air around the tyre. The company’s researchers employed both aerodynamic simulations and wind tunnel testing to tackle the problem; in 2010 it developed aerodynamic simulation technology to simulate the flow of air around tyres in actual use conditions, and Yokohama reports that the scope of simulation is presently being expanded to include the entire vehicle.

These simulations and wind tunnel tests resulted in a tyre design where fin-shaped protuberances are present on the side facing inwards toward the wheel well when mounted. Test results showed that while drag on the tyre itself was worse than on a standard tyre, drag on the vehicle as a whole was considerably reduced. Overall drag was lowered due to changes in pressure within the wheel wells caused by the presence of a flow of air spiralling in the direction of the tyres rotation – a flow induced by the fins.

The technology was unveiled on 19 December at the 26th Computational Fluid Dynamics Symposium in Tokyo, and it will also be presented at February’s Tire Technology Expo 2013 in Cologne, Germany. Going forward, Yokohama says it will conduct further research on the relationship between tyre shape and air flow and assess tyre performance on actual vehicles.