Michelin IMSA Insider: Marking Time at the Speedway

It has been nearly a decade (2014) since the top IMSA series has raced at the Indianapolis Motor Speedway.

The cars have changed from Daytona Prototypes to the exciting new IMSA hybrid GTPs, tires have changed to Michelin, and with the changes in times, cars, and tires, laps times have also changed by as much as three seconds per lap.

But with IMSA’s return for this week’s Battle on the Bricks and the recently announced six-hour event here in 2024, teams are working hard to find the secrets of the IMS road course.

Getting Fresh

Recent WeatherTech Championship and Michelin Pilot Challenge testing and Porsche Carrera Cup North America events have provided teams and Michelin engineers with fresh data on the 2.439 mile 14-turn circuit.

“The track surface itself is what we characterize as ‘macro rough’, meaning that it helps with mechanical grip,” said Hans Emmel, Michelin WeatherTech series manager.

However, that track surface grip comes at a price. “Tire wear needs to be carefully managed,” said Emmel.

The GTP and LMP2 entries are allocated only six sets of the Michelin hard compound tires for the weekend, with only three of those sets available for the two hour 40-minute race.

Home Field

Indianapolis is certainly familiar territory for top IMSA GTP teams as Chip Ganassi Racing (Cadillac), Team Penske (Porsche), Rahal Letterman Lanigan (BMW), and the Acura entries from Meyer Shank Racing and Andretti Global (in IMSA with Wayne Taylor Racing) have already raced twice this year on the IMS road course.

The track is sensitive to sun, and track temperatures can quickly change due to direct sun or cloud cover. Changes in wind speeds and direction can also play havoc with chassis set ups.

The clockwise track direction increases loads and wear on left-side tires, so Michelin expects single stints on left side tires, with possible double stints on the right-side tires.

Go Fast then Hit the Brakes

One of the keys to success on the IMS road course is finding the happy balance between braking for Turns 1 and 7, managing through the infield sections, then optimizing the all-important Turn 14, the final turn leading onto the fast, long main straightaway.

Tires provide the mechanical grip while absorbing that straightaway energy and momentum. Finding the braking balance and a mechanical balance that will produce equal tire wear throughout potentially long green flag stints is essential.

With all five IMSA classes in the 48-car WeatherTech Championship field, drivers will be in near constant traffic as they set up or complete passes off-line, where the marbles will quickly develop.

And There’s More

In addition to the WeatherTech Championship race, the Michelin Pilot Challenge teams will take on the second four-hour race of the season (Daytona), in a 4:30 to 8:30 p.m. battle into Saturday evening’s sunset.

In addition to a great new experience for Pilot Challenge teams and drivers, the event will also help to provide insights for the longer WeatherTech Championship race into darkness in 2024.