Interview with Hankook engineer Baltes: Tread of the Formula E tire "made of 2 different rubber compounds"

After eight seasons with tires from Michelin, the 2023 Formula E World Championship will start next weekend for the first time with tires from the South Korean manufacturer Hankook. The company is breaking new ground with the development of the Hankook iON Race all-weather tire. 'e-Formula.news' had the opportunity to speak exclusively with Hankook's chief motorsport engineer, Thomas Baltes, during pre-season testing in Valencia.

Thomas, what was your focus when developing the Hankook iON Race for Formula E?

Generally, the challenge with this project was that we had to start from scratch. It was a completely new vehicle and therefore a completely new challenge for us at Hankook. We won the FIA bid for the Formula E World Championship long before the Gen3 car was developed. That forced us to look for alternatives to start testing.

How did you go about this?

First it was about the design and tire dimensions, then about the direction of the first prototype tire. Only when the road-ready prototype was available did the actual tire development begin under real conditions. In the course of this development work, all parameters were then matched step by step to ultimately present the Formula E tire for the new generation. In Mexico City, we will see how the final result performs under competitive conditions.

What kind of specifications were made by the FIA?

For a world championship, there are very clear guidelines that a tire has to meet. These include, for example, durability, dry and wet performance, but also very different road conditions, as the races are mostly held on city circuits. We are always faced with such challenges in motorsport, but Formula E is a very special challenge for the tire manufacturer for the reasons mentioned above.

You said you tried to simulate the car. How did you go about that?

Because there was no Gen3 car at the beginning of development, we had to go elsewhere to complete the base of our development work. We did that with a heavily modified Formula car, which was very close in characteristics to a Formula E car.

Lucas di Grassi said during the press conference here in Valencia that the tires were so hard that you could do the entire test week on one set of tires. Is that really the case, or is di Grassi exaggerating?

We don't generally rate such statements - but it does speak between the lines for the Hankook product.

The subject of lap times also came up here in Valencia...

Naturally, the main focus for many is first on the lap time. But what is only marginally - if at all - taken into account is that the final test of the teams takes place in Valencia. Although times are also taken into account, the main focus is on other things. In addition, the track conditions here are different from those found on non-permanent circuits during the season.

Since this season, the Formula E sporting regulations have stipulated that drivers are not allowed to spin their tires on the way from the dummy grid to the starting grid. From Hankook's point of view, is there a reason for this?

No, from Hankook's point of view, there is no specific reason for this. The regulations were not changed in this regard at our request. The assumption is that this is to prevent the "heating up" of the tires, so that the same starting conditions apply to everyone.

Last season in New York City, we had a situation where it started to rain just before the end of the race. Since the tires didn't have much tread left, aquaplaning occurred. How do you make sure that doesn't happen with your tires?

This is precisely one of the big challenges of Formula E and one of the issues we paid special attention to during development: to develop a tire that ensures stable performance from start to finish - even on wet surfaces.

So it played a role in the development that the tires still have so much profile towards the end of the race, so that in the event of a rainstorm no aquaplaning occurs?

After a certain depth of water on the road surface, aquaplaning can always occur. Our goal is to provide drivers with enough tire tread at all times - including at the end of a race - to manage such situations.

In Formula 1, the tire manufacturer has various tire compounds from which it selects the tires that best suit the track. In Formula E, too, there are races in rather cool conditions on the one hand and heat races on the other. Was it never an option to develop different tire compounds for this?

The objective of Formula E is completely different. Racing with different compounds would not currently be what Formula E stands for.

So it's always a compromise solution?

At the end of the day, a tire - for whatever use - is a kind of compromise. This is also true for Formula E. However, we are also talking about high-end racing cars and a tire that has to meet all the demands placed on it.

What exactly does this compromise look like with your tire?

The special thing about the Hankook iON Race is that it is a completely newly developed hybrid tire. Put simply, the tread consists of two different rubber compounds. The inner side of the tire is responsible for the required wet grip and the outer area for the dry grip. This is, of course, another new challenge for drivers to get used to the new Hankook iON Race in order to take full advantage of its performance.

Have you ever done this before - use two different rubber compounds on one tire?

We have been testing this technology for quite some time now. With Formula E and its special challenges, Hankook has decided to bring this technology to bear here - a new innovative generation of Hankook racing tires for electric racing vehicles.