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Reinventing the wheel

Andreas Valencia Pollex is a wheel designer for Audi and is currently reinventing the wheel for electric vehicles—in terms of both design and aerodynamics.

02/18/2021 Interview: Bernd Zerelles – Photo: Robert Fischer Reading Time: 6 min

The plastic insert for the Audi aero wheel looks like a wing.
Aerodynamic plastic inserts give the Audi wheel designers new design options.

Mr. Valencia Pollex, electromobility has brought special demands in terms of design and aerodynamics. On the one hand, it allows new approaches to design. On the other, wheels are getting bigger because they have to carry more weight. However, large wheels present challenges in terms of aerodynamics. As an Audi designer, how do you manage this balancing act?

First and foremost, a wheel is a safety-relevant component. All the forces generated by a car are transferred to the road via the wheel/tyre configuration. Yet unlike a chassis component, the wheel is visible to the outside. We wheel designers are thus creating something that has to meet the technical requirements while at the same time satisfying design aspects. The energy balance of an electric vehicle is crucial so the focus has shifted accordingly. Previously, wheels really only had to deliver on strength requirements. Today, we are developing and designing intelligent aero wheels with maximum possible efficiency. After all, this has a big impact on the range of an electric vehicle.

 

 

What is it that makes an ideal aero wheel?

The perfect interaction of vehicle body, tyre and alloy wheel—and the position of the wheel in the wheel housing. To ensure perfect aerodynamics, we need to achieve a certain flatness so that the air hitting the front of the car is diverted around the vehicle body without causing strong turbulence along the sides. The paradox here is that creating flatness on a wheel always involves quite a lot of work. A closed surface means using more material and, in the case of aluminium, that results in a certain weight increase. That’s why we have used plastic to create the closed surfaces on the wheels for the Audi e-tron GT quattro. This keeps the wheel weight down. Another factor is that, like anywhere in the energy equation, speed plays a major role. Areas that move fast have a greater impact on aerodynamics than slower-moving areas. This means the center of the wheel can be ignored. But there’s a lot of aerodynamic leverage to be gained on the outer areas of an aero wheel. In short, it’s very complex.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Why don’t you just put a flat cover on the wheel?

Our customers who buy a beautiful premium vehicle expect absolute functionality but also uncompromising aesthetics. On wheels, extreme flatness is not yet accepted as being beautiful. Our aim is to develop an aesthetic that conveys the innovation of electromobility while meeting our customers’ expectations. Besides, from a purely technical viewpoint, it’s not possible to use entirely closed wheels. If the brakes are deprived of air, the brake fluid would eventually boil and cause a safety issue. A certain amount of ventilation is essential. In aerodynamic terms, we have nevertheless succeeded in balancing the geometry of this wheel for the Audi e-tron GT quattro so that it makes no difference whether the air sweeps across all the angles and openings or whether the surface is entirely closed.

 

Don’t the openings cause an air vortex?

No. Together with our aerodynamicists, we have found the exact sweet spot that lets air through to the brake while steering the airflow as if the surface were closed. At the speed at which it flows through the wheel, the air can only react as dictated by physics. In aerodynamic terms, the Audi e-tron GT quattro wheel represents the absolute state of the art.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Audi wheel designer Andreas Valencia Pollex explains the aero wheel.
Some of the equipment depicted or described is optional and only available at an additional cost. The information covering standard and optional equipment on this website is specific to the German market. Detailed information on standard and optional equipment in your country is available from your national Audi website or from your Audi partner.

Is the frame of the aero wheel still made from aluminium? Is plastic only used for the cover components?

That’s right. If you look at the wheel from the inside, you’ll see five straight spokes which ensure maximum stability. Aluminium remains an essential material for wheels. Its technical properties, such as plasticity and strength, don’t change. Aluminium is also resistant to the tremendous heat generated by the brake on the inside of the wheel. Having said that, a classically designed five-spoke wheel would be virtually ineffective aerodynamically. And creating a flat aluminium part would have made the wheel too heavy. During the development process, we found we could use plastic inserts to close the surface. This makes the wheel particularly light. The properties of the various plastics are very interesting in terms of identifying which plastic will withstand brake heat at which point on the wheel. It’s extremely time-consuming to design a lightweight wheel like this; it certainly doesn’t compare with creating an industrially produced aluminium wheel. 

How did you approach designing this wheel?

The top priority was to achieve a progressive design. We started by sketching a wheel with a certain flatness to prevent major errors creeping in right from the outset. But the wheel’s final design was the result of perfect collaboration with colleagues in manufacturing, production and aerodynamics. One example is this key two-part plastic component that creates flatness and looks like a wing. The two parts are clipped together and then screwed to the wheel at a different geometry. We really wanted it to be a bicolor component. Initially, the light-colored part was made from aluminium but that turned out to be too heavy. So we had to use a plastic, which we precision-coated. We weren’t trying to recreate high-sheen aluminium. The intricate interplay of all disciplines is the only way to achieve the precision needed to create this component with the progressive design and durable construction that can withstand all driving conditions in any weather.

 

 

So plastic not only reduces weight but gives you more options as a designer?

Using plastic adds a new dimension. Previously when designing a wheel, I always had to take a certain edge radius into account for physical and construction reasons. If the edges are too sharp, forces will concentrate there. And that’s where an aluminium component will break. It’s different with plastic. Now I can create high-precision details like this texture—that just wasn’t possible before. And the “Colour and Trim” design team introduced us to coatings I’d never previously heard of. A whole new universe is opening up to us wheel designers.

A whole new universe is opening up to us wheel designers.

Andreas Valencia Pollex

Detailed illustration of the Audi aero wheel.
Some of the equipment depicted or described is optional and only available at an additional cost. The information covering standard and optional equipment on this website is specific to the German market. Detailed information on standard and optional equipment in your country is available from your national Audi website or from your Audi partner.

Where is the Audi DNA in this wheel design?

Basically, the Audi DNA can be found in every part of the wheel. Each and every detail radiates design quality: the clarity, the precise choice of angles, the balance of the lines that come together in an arc. If you have an eye for design, you’ll appreciate this quality. And if you don’t know a whole lot about design, you’ll still find it soothing on the eye because everything about the wheel is appealing. That’s Audi DNA. That’s design quality. At the time we designed the wheel, the goal was to make the Audi e-tron GT quattro look as progressive, electric, modern and sharp as possible. You’ll find all that in this wheel. 

 

What design feature of this Audi e-tron GT quattro wheel would you like to highlight?

If you wanted to highlight something especially progressive, it’s the twisted spokes. We accentuated this twist because it contradicts prevailing aesthetics. It makes the wheel look new, cutting-edge. Over time, people get used to a certain way of looking at things—even if they don’t know why they’ve got used to it or what it is they’ve got used to. It’s all about breaking the habitual mold. Of course, that may also have a polarising effect. By persisting with this break with aesthetics, you achieve a sense of modernity. In this case, it’s the interplay between what you want to see—in other words, concentric spokes—and a twist that’s perceived subliminally so that it doesn’t polarise. Then add texture, something that’s undergone a strong and very modern evolution in the design world in recent years. At Audi, these recurring lines are a feature of our design idiom for electric vehicles. They can be found, for instance, in the light signature on the Audi e-tron and now also in the wheel design. The multicolored Audi e-tron wheel also demonstrates a certain visual complexity. And like the visible movement of a high-end watch that a layman cannot really understand, what looks complex is desirable. It’s exactly the same thing with this wheel. You can see that various components have been brought together to make a whole and that each individual component is a natural part of something bigger.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Audi e-tron GT quattro: Power consumption, combined*: 19.6–18.8 kWh/100km (NEDC); 21.6–19.9 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

Stated specifications apply only in Germany and are not applicable in other regions.

Discover the Audi RS e-tron GT in your country

Discover the Audi RS e-tron GT in your country

Audi models give customers lots of freedom to personalise their cars. Learn more about the equipment that comes with the Audi RS e-tron GT and which interior and exterior options are available on request.

Discover now

Audi RS e-tron GT: Power consumption, combined*: 20.2–19.3 kWh/100km (NEDC); 22.5–20.6 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

German model shown. Stated specifications apply only in Germany and are not applicable in other regions.
Some of the equipment depicted or described is optional and only available at an additional cost. The information covering standard and optional equipment on this website is specific to the German market. Detailed information on standard and optional equipment in your country is available from your national Audi website or from your Audi partner. 

Audi RS e-tron GT: Power consumption, combined*: 20.2–19.3 kWh/100km (NEDC); 22.5–20.6 kWh/100km (WLTP)CO₂ emissions, combined*: 0 g/km

German model shown. Stated specifications apply only in Germany and are not applicable in other regions.
Some of the equipment depicted or described is optional and only available at an additional cost. The information covering standard and optional equipment on this website is specific to the German market. Detailed information on standard and optional equipment in your country is available from your national Audi website or from your Audi partner. 

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