The role of tire pressures, and especially for the front tire, has grown in importance in recent years, as aerodynamics and ride-height devices have made the front ever more sensitive to pressure and temperature changes. It is common to hear riders complain of temperatures and pressures skyrocketing after getting stuck behind other bikes, and kept out of the cooling air.
It is therefore not surprising that factories and teams try to manage tire pressures as carefully as possible. By lowering the pressure, they can keep tire temperatures lower and allow the riders to better manage the front tires over the duration of the race.
They have to be careful not to go too low with tire pressures, however: like all motorsports series with a spec tire, MotoGP has a minimum pressure for both front and rear tires: 1.9 bar front, 1.7 bar rear. Tire pressures are monitored by sensors and recorded by the spec datalogger, and pressures have to be over the minimum for at least half of the race.
Bending the rules
It will also not come as a surprise that some teams and factories have been playing fast and loose with the permitted tire pressures. Factories are always looking for an advantage, and willing to exploit them when they find them.
What may be more surprising is that the factories and teams all know about the minimum pressure rules being disregarded, and that they all accept this when it happens, allowing those who transgress the rules to go unpunished.
This was revealed by veteran MotoGP journalist Mat Oxley in his latest blog for Motor Sport Magazine. Oxley was leaked the official tire pressure sheet issued by Michelin to all of the teams after the race at Jerez, which showed that four riders had been riding with pressures that were too low.
How low can you go?
The rear tire of Andrea Dovizioso's RNF WithU Yamaha was under the minimum pressure for one lap short of the twelve required, as was the front of Alex Rins' Suzuki GSX-RR. But the front tires of two Ducati riders were most striking: Jorge Martin's front tire was only at minimum pressure for a single lap, though the Pramac Ducati rider crashed out at the final corner on the first lap, and spent the rest of the race trying to catch up.
Race winner Pecco Bagnaia's front tire pressure was below the minimum pressure for the entire race, however. There was not one lap on which his front tire pressure was within the permitted pressures. And yet Bagnaia went unpunished, and his victory was allowed to stand.
Angered by the current state of affairs, senior members of rival factories sent Oxley the relevant data. Despite the rules stating quite clearly that tire pressures must be below a certain minimum, the MSMA – the association representing the six factories in MotoGP – have a so-called "gentlemen's agreement" not to punish any infractions of the tire pressure rules.
That, however, will change for next year. As it happens, I spoke to Michelin's head of two-wheeled motorsports, Piero Taramasso at Portimão, together with Peter Bom. We spoke to him at length about a number of issues, and one which came up was the issue of tire pressures.
The minimum tire pressures were in the rulebook, Taramasso told us, but penalties would not start to be applied until 2023. "This is in the regulations, it's written in all the documents, in the rule book," the Michelin boss said. "So this procedure is in place, but starting next season, we will still apply the procedure, but we will apply penalties for teams and riders who do not respect that."
At the moment, there are no penalties, only a system of warnings, Taramasso told us. "For the moment there's not a penalty, there's just a warning, like a yellow card and red card." The fact that all of the data is published and distributed to all the teams after every race is meant to encourage teams and factories to respect the rules. "Everybody is aware of what happens, this is what is good. We share all the results with all of the teams, all of the riders, so everybody knows who is respecting or not. So it's very open. We work with trust and with confidence with everybody. But starting next season there will be penalties for people who are not respecting it."
Transgressions are rare
Falling below the minimum pressure was not common, Taramasso told us. "I will say it's very rare." There was relatively little to be gained by dropping below the minimum on the rear tire. "For the rear pressure this season, everybody respected. In the front, it happened twice, one rider and another rider, different manufacturers. But it was just by a very very little bit," Taramasso said.
This statement was made before the first MotoGP race back in Europe, at Portimão, after riding at tracks where stable conditions have barely prevailed. But two races later, four more names had been added to those two initial transgressors.
Taramasso explained in some detail how they monitored tire pressures. The data from the sensors is written to the dataloggers, and tire pressures monitored and recorded by Michelin techs before and after each session and each race. Usually, the pressure was taken wirelessly from the sensor using a handheld unit, but when the sensors were not returning data, Michelin techs would use traditional manual pressure gauges.
Based on that data, Michelin could determine whether the pressures had been legal throughout the race. "For the moment, we measure pressures over all the race distance, and for the moment – but we are discussing whether to change or not – at least half of the race has to be at the minimum pressure," Taramasso told us. "It's exactly the same rule that they use for Moto2. It's the one we use also in MotoE."
Because tire pressures rise as the riders work the tires during the first laps of a race, it was normal for riders to start the race below the permitted pressures, he explained. "The way the tire works, you start lower and after four or five laps it goes up to the target and then it stays stable until the end." That pressure, and the temperature of the tire, could be affected by all sorts of factors, including whether a rider was following other bikes. "The rear pressure is quite stable, but then the front can do up and down, depending on the track, on the position, etc."
Fairness and reliability
The aim, as Taramasso explained, was to have an enforceable rule which all of the manufacturers agreed to and were willing to abide by. Discussions were underway about exactly how much of the race the pressures needed to be above the minimum for, but the other part of that equation was switching to a single supplier for tire pressure sensors.
"In order to have a reliable measure, we need everybody with the same sensor, and today we have three different manufacturers, so we needed to pick one for this. So that everyone has the same, because the tolerances are different," Taramasso said. Different sensors with different precision tolerances meant it was hard to compare the values recorded between the different bikes. This is particularly tricky, given the infractions being noted were so close to the permitted values.
More functions, more problems
Reliability would be key. As sensors have become more capable and had more functions added, they have also become more prone to malfunction. Pressure sensors have temperature sensors built in, but some also have infrared temperature sensors embedded as well, to measure the temperature on the inside of the carcass, a more accurate measure of the temperature of the actual tire rubber than simple air temperature sensor commonly used.
Those sensors are commonly more fragile, however. One major manufacturer has already switched from the more sophisticated sensors such as produced by McLaren to the utterly reliable and proven 2D sensors. For those who closely follow tire usage, the frailty of the sensors used is reflected in the tire data. At the moment, the sensor data is automatically recorded each time the riders enter or exit pit lane, and is shown on screen using the telemetry collected by Dorna. But sometimes that tire data is missing, and has to be added by hand to the results after a race or session is over.
Even if that data is not logged, the manual measurements can still provide enough information, Taramasso explained. "We have data because we check in the box when they go out and go in, so you can deduct how much it was."
All change in 2023
The new rules, including penalties, to be introduced from 2023 would extend beyond just the race, as the rules are currently enforced. "Next year, it will also be for practice and qualifying," Taramasso explained. Whether that data would also be shared with the teams was yet to be decided. At the moment, the only data that was shared with all of the teams was the data collected during the race.
In response to accusations made by rival teams, Ducati Corse boss Gigi Dall'Igna spoke to a small group of mostly Italian journalists. His response was largely just a repeat of what we were told by Michelin's Piero Taramasso at Portimão. You can read a transcript in Italian over on the GPOne.com website.
Whether any of this will lead to change in the short term is unlikely. But the wheels have already been set in motion to institute changes for the 2023 season. Riders may be racing with pressures below the permitted minimum in 2022, and going unpunished. But that will not be the case from next year.
Here to stay
Despite all of the controversy which inevitably comes with being the official supplier of arguably the most important component on a racing motorcycle, Michelin were in for the long haul, Taramasso told us at Portimão. "This is for sure," the Michelin motorsport boss told us.
Racing offered unique opportunities to develop their product, Taramasso said. "This is one of the reasons we are in MotoGP, it's to develop, to be able to do some tests, try different things, different tires, different profiles, different casings. This is what we want to do. And thanks to the teams, thanks to Dorna, we are able to do it."
The global pandemic had had a negative impact on their plans, he said, but there were big plans for the future. "The Covid-19 situation slowed down a lot, because we have a lot of ideas, but for the future we will be able to do that. One thing we want to do also is to develop the sustainable materials, the one we use in MotoE for example. We use regenerated, recycled material." That is precisely the sort of technology which will trickle down to road tires very quickly.
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