Michelin and endurance racing’s hybrid prototype era

The 2020 8 Hours of Bahrain in November brought the age of hybrid LMP1 prototypes to a close. Introduced in 2012, these technologically-sophisticated machines notched up 61 world-class endurance racing wins, all on Michelin Pilot Sport tyres which delivered on their Performance-Made-to-Last promise. From 2021, the hybrid generation will make way for a new breed of Hypercars.

Ahead of the introduction of these petrol/diesel-electric monsters, global carmakers Audi, Peugeot, Toyota and Porsche all announced exciting, ambitious projects aimed at backing the promotion of their respective hybrid roadgoing models. All four approached Michelin to work at their sides.

The Peugeot 908 HYbrid4 was unveiled at the 2011 Geneva Motor Show, Switzerland, and the Audi R18 e-tron quattro made its first competitive appearance at Belgium’s 6 Hours of Spa-Francorchamps in May 2012. The Toyota TS030 Hybrid joined the fray the following month at Le Mans, France, while the Porsche 919 Hybrid was revealed two years later at Le Castellet, France.

Nissan also dipped a toe in the water with its revolutionary Nissan GT-R-LM which broke cover in 2015.

These five cars featured different solutions. Audi, for example, opted to restore the electrical energy recovered under braking through the front wheels, making it four-wheel drive, as did Porsche which went for a double energy-recovery system. Toyota’s solution featured a combination of rear-wheel drive and a super-capacitor system, whereas Nissan ran a KERS-equipped front-wheel drive configuration. The internal combustion engines that powered these machines featured different combinations of a V8, V6 or V4 diesel or petrol powerplant, with or without turbocharger. Power outputs ranged from 700 to 1,100 horsepower.

Michelin’s ‘Hybrid’ tyre

“The advent of endurance racing’s hybrid prototypes brought about a change of tyre sizes in LMP1,” recalls Jérôme Mondain who ran Michelin’s endurance racing programmes in the mid-2010s. “They switched from 36/71x18 at the front and 37/71x18 at the rear to 31/71x18 front and rear. The biggest challenge we faced was providing these advanced cars with the same levels of performance and consistency despite their smaller tyres. Our engineers and development specialists started from a clean sheet and the result was a new-generation Pilot Sport Endurance range.”

“Narrower tyres meant a smaller contact patch and, on paper, less grip,” notes one of the Michelin Motorsport engineers who worked on the project. “The tyres’ overall volume was smaller, too, yet the hybrid LMP1s were heavier and generated greater aerodynamic downforce. We were consequently faced with having to deliver both upgraded performance and extra grip, and we achieved the two thanks to the use of new materials, combined with fresh approaches to our design and production processes which went on to be taken up for the development of road tyres.”

The new Michelin Hybrid appeared in 2012 and was an addition to the firm’s wet-weather offering, fitting in between the slicks and intermediates, hence the name ‘Hybrid’. Despite having no tread pattern, this major innovation proved especially effective in drying conditions and was first used competitively at the 6 Hours of Spa-Francorchamps in 2012.

“The idea was to allow the drivers to stay out on a drying track with a wet-weather tyre as long as possible,” explains one of the Michelin Hybrid’s designers. “Without grooves, the only way this tyre could clear water was via the contact patch, and this was achieved with new materials and a new crown design. The development phase lasted around 18 months.”

Hybrid prototypes at the peak of the endurance racing pyramid with Michelin

The first carmaker to win a race with a hybrid LMP1 prototype was Audi whose R18 e-tron quattro scooped first and second places at the 2012 Le Mans 24 Hours. After that landmark success, the Michelin-equipped hybrid generation went on to dominate the FIA World Endurance Championship. Toyota scored its first victory with the TS030 Hybrid at the 2014 6 Hours of Fuji, Japan. The TS040 Hybrid’s maiden success came at the 2015 6 Hours of Silverstone, Great Britain, and the TS050 Hybrid got its score off the ground at the 6 Hours of Fuji in 2016. The Porsche 919 Hybrid’s debut win was the 2014 6 Hours of Sao-Paulo, in Brazil.

Of the 66 FIA WEC rounds that have taken place across Europe, Asia and America since 2012, 61 were won by hybrid LMP1s. The Toyota TS050 Hybrid claimed 19 of those, including three Le Mans victories on the trot, a feat matched by both the Audi R18 e-tron quattro and Porsche 919 Hybrid. Indeed, the three-cornered battles that opposed Audi, Porsche and Toyota were some of the most thrilling world-class motor racing has ever seen.

Next season, the hybrid LMP1s will pass the baton to the new Hypercars which will be authorised to feature hybrid or non-hybrid power. They are poised to make their debut in March at Sebring, Florida, USA, and Michelin has been chosen as the class’s control-tyre supplier.

“We are working on a new Michelin Pilot Sport range for the Hypercars which will be heavier than the LMP1s,” notes Pierre Alves, the present manager of Michelin Motorsport’s endurance racing programmes. “That said, they won’t generate as much downforce and that has a big influence on tyres. Sizes will remain at 31/71x18 all-round for the hybrid Hypercars, but the non-hybrids will fit 29/71x18 fronts and 34/71x18 rears. The development of these new tyres involved digital modelling and simulation, and they were submitted to their first track test recently on a Toyota GR Super Sport. The data we collected was totally in phase with our calculations.”