Bringing tires to an IMSA race is no easy task. There are three different varieties of tire being used on track at once. You have to think about rain. You have to think about compounds. And for a 10-hour race like Petit Le Mans at Road Atlanta, the challenge is even greater. So I followed Michelin around for a weekend to see how its tire operation compares to something like what Pirelli does for Formula One.
Full Disclosure: Michelin paid for my trip to Road Atlanta for Petit Le Mans, which included lodging and food.
When the IMSA circuit rolls into town, so does Michelin, along with 19 tractor trailers full of equipment. That includes the supplies to build a 24,000 sq-ft. tent in addition to mounting and dismounting equipment, and the pit lane engineering tent. Oh, and all those tires.
For a 10-hour race like Petit Le Mans, Michelin brought roughly 7,800 tires, which Ken Payne, Michelin’s motorsport director, told me Michelin personnel will mount and dismount roughly 33,000 times per weekend. For most of the races on the IMSA calendar, the four- to six-hour events, you’re looking at a much smaller number. For something like the Rolex 24 at Daytona, Michelin averages around 12,000 tires. Its record so far is 17,000, which it brought to Sebring during the IMSA/WEC doubleheader.
One of the more fascinating elements of the tire supply, though, is that all the classes use one of three tires, each with a different level of confidentiality. With something like Pirelli, all the tires it provides to various feeder series are well-kept secrets. They’re never something you can take home with you or poke at as a team.
The GTD class, though, uses entirely commercial tires, the kind you can go to the shop and have put on your car right now. These teams buy the tires, and they keep them and do with them whatever they please when the race is over. And the GTD class, along with the Michelin Pilot Challenge series, only use hard-compound tires. It keeps the costs — and the number of tires that need to be available at the track — down.
And the higher-level classes — DPi and LMP2 — don’t use the fully confidential tires, either. They’ve got a semi-confidential compound, which basically means Michelin kinda-sorta uses these tires as a proving ground for materials that aren’t always on the market, but Michelin also isn’t keeping a strict watch on these tires. Teams can take them back to the shop after a race to examine, but once they’re done with them, teams have to return the tires to Michelin.
That means GTLM features the confidential tire. Instead of buying tires from Michelin, then, teams pay a fee to Michelin that essentially covers the provision of tires and an engineer to keep up with the team at the track.
These tires, though, aren’t the same — manufacturers get a close say in the development of these tires. So, Michelin engineers will work with Corvette to develop a tire that will specifically work with Corvette, while different engineers will work with BMW to create a tire specifically for the BMW. The teams aren’t necessarily sitting in the Michelin lab while their tires are being created, but they can influence the development to suit their cars’ particular characteristics.
Those confidential tires are the ones that don’t leave the race track. Michelin divvies up the tire allocation when teams get to the track, and it collects all those tires before teams leave. In some cases, Michelin will even go out and scavenge for tire scraps on the track if there was unexpected degradation or a blow-out.
They keep an eye on things through RFID sensors, which are embedded in the tire and contain all the info about that tire: when it was made, where it came from, when it was fitted onto a rim, when it’s used on the track, and for how long.
To staff races, Michelin relies on a staff composed of full-time motorsport engineers and volunteers from other areas of the company that might have an interest in moving to the racing world. After all, someone needs to put all those tires on rims. And then take them off. And then put them on again.
Michelin also has the ability to do on-site tire biopsies, which it’ll usually do in instances where the tire doesn’t appear to be wearing properly, or when a team is having issues. It can dissect tires layer by later to analyze everything from the rubber adhesion to internal stress. That way, Michelin can give feedback to teams about how to best use the tire that weekend, and any issues are rolled into future development opportunities.
When I asked Michelin how long it takes to actually develop tires for racing purposes, they said it can be difficult to tell, but while they’re usually focusing hard on development six months out, it’s a process that never really stops. If something needs to be resolved before the next race, there’s a good chance that’s going to happen rather than waiting for the next season.
When all those tires hit the end of their life cycle, they’re shredded up and used in consumer goods. Unless they’re confidential tires. Then they’re incinerated as a fuel source. Generally, tires that are used during one weekend are considered old news and ready for recycling.
When all is said and done, Michelin techs are likely some of the first people to arrive at the track for the weekend, and they’re also some of the last to leave, since the tires are the bedrock of motorsport. You can’t get on the track until you’ve received your tire allocation for the weekend, and you can’t go home until those tires are taken care of. Having the chance to spend time with Michelin was a fascinating look behind the curtain of one aspect of motorsport you really only think about when things are all falling apart — and it’s kind of astounding what goes into the development process.