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Opinion

The challenges of making Hypercar tyres without heaters

The World Endurance Championship made the bold step for 2023 of moving to tyres without heaters. Michelin’s motorsport director reveals how its latest product developed exclusively in the virtual realm breaks the mould

Hypercars Michelin tyres

I was excited and happy to get the brief from the FIA and Automobile Club de l’Ouest to develop tyres that work without using warmers for the 2023 World Endurance Championship. It’s a regulation change that Michelin has been strongly pushing for the last couple of years. We included it in our proposal answering the tender for Hypercar tyres in 2019 as an idea of an innovative change we could bring.

It can look odd for fans to see the family of racing spending energy to heat tyres – even when it’s 40C in Bahrain. It’s not easy to explain the need to do that when fewer series are depending on tyre warmers now. Having supplied the IMSA Sportscar Championship since early 2019, we said: “We feel capable of making tyres that start from cold and last two or three stints as long as it’s a different compound between Bahrain and Spa.”

We want to respect the safety of drivers because it’s in nobody’s interest to have accidents. And we know that a tyre starting at cold is never going to be as performant as its operating temperature range, so you want it to work relatively well at the first corner.

But a tyre that reaches its optimal window faster will normally drop off sooner, so we had a Catch-22. For it to be durable and reward those who don’t change tyres – I believe whoever can manage their materials the best should have an advantage – then it will take time to warm up because it’s a hard tyre. But we were confident that we had the technology and experience to make this possible.

The 2023 Hypercar tyres were developed entirely using simulation, a process that was well-defined from the range for 2021. We didn’t get any data on the previous generation of Hypercar tyres starting from cold because teams were still permitted to use tyre warmers, but we had plenty of information from the DPi tyres in IMSA about where we need to be and we had the information on the previous Hypercar tyres. So we devised a mix in the design philosophies to come up with a model which was tested in the simulator, and this helped us to define the three different compounds: the soft, medium and hard.

Michelin's new-for-2023 tyres were made using a blend of previous Hypercar tyres and DPi rubber that worked without heaters

Michelin's new-for-2023 tyres were made using a blend of previous Hypercar tyres and DPi rubber that worked without heaters

Photo by: Michelin

At some tracks it’s hard to know what temperature to expect – and as the LMDh and LMH cars are different in terms of stress and the set-up, our recommendation has always been to bring two options per track to give us a good compromise. Simulation has helped to avoid the overlap between the two specifications and ensure you don’t have a big zone where one is too hard and the other one is too soft.

Tame Tire is for us the magic tool that has been coupled with the simulator to allow us to accurately model how a tyre will perform at a given temperature, over a given mileage on a particular surface. The physics is in the public domain, but it’s how you assemble these where there is a lot of knowhow, and Tame Tire is the result of 20 years of efforts in simulation at Michelin in motorsport.

Based on driver feedback in the simulator you can adjust the parameters, and from the virtual tyre we know what functional parameters have to be designed to reproduce the feeling this model gives the driver

How you use a tyre at the start of its life naturally impacts its performance in the end, so wear models and various phenomena are all integrated. We can always do more to tune it to the real data; we’re still unable really to simulate the wet, and even in the dry some things aren’t easy to reproduce like how the track rubbers in, but it’s improving all the time.

Based on driver feedback in the simulator you can adjust the parameters, and from the virtual tyre we know what functional parameters have to be designed to reproduce the feeling this model gives the driver. As a designer, it’s useful to know ‘he likes stiffer tyres, we need to change the compound properties’, and we can take that information back to the physics.

We use Tame Tire not just to reproduce what happened on the track, but also to design a tyre with no information except the feedback from a driver in a virtual car.

Michelin's Hypercar tyres for 2021 and 2023 were all developed entirely using simulation

Michelin's Hypercar tyres for 2021 and 2023 were all developed entirely using simulation

Photo by: Michelin

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