Eddy on tire pressure: the background to the problem / MotoGP

Existing MotoGP tire pressure sensors are inaccurate and can be tampered with, so factories do not accept sanctions if someone is caught under low air pressure – like Bagnaia. An analysis of Ing. Cracks.

Ducati factory rider Pecco Bagnaia rode all 25 laps of the race with illegally low tire pressure during his victory in Jerez, it became clear this week. The allowable tire pressure had also dropped in the case of Pramac Ducati factory rider Jorge Martin, who initially dropped and remained without a point. – during 24 of the 25 laps of the race. Alex Rins and Andrea Dovizioso also violated the tire pressure rules at the Spanish GP. But there are no sanctions because the situation is complicated.

Since the Mugello GP 2016, the MotoGP World Championship has required sensors on the rear and front wheels to monitor tire pressure. Since 2016, the minimum tire pressure for front-wheel slicks has been 1.9 bar and for rear-wheel slicks 1.7 bar. In Moto2, 1.5 bar is allowed at the rear. However, the established values ​​are not reliable, which is why the six MotoGP manufacturers have decided not to accept fines.

This agreement has been in existence for some time. Two of the best known sensor manufacturers are LDL and McLaren.

The engineers from the six MotoGP manufacturers have a huge secrecy surrounding this topic. For, of course, it is unpleasant and embarrassing that the details of this secret agreement have now been leaked to the public.

Meanwhile, desperate attempts are being made to find out where the leak is. The suspicion that it could have been Honda (only 6th place in the manufacturers’ championship and therefore disappointed) or Aprilia (arch-rival of Ducati, Gigi Dall’Igna left there in October 2013) cannot be substantiated. Ducati, Yamaha and Suzuki were hardly there as they stayed below the legal minimum requirements in Jerez and will hardly make an effort.

In any case, the Race Direction at one point expressed the desire to introduce some minimum limits for tire pressure in the MotoGP class, in order to monitor them and punish offenses. In the worst case, disqualification from the race would have threatened, which happened for Fabio Quartararo in Moto2 in Japan 2018.

This intention was presented to MSMA at the time, but all manufacturers shouted and resisted. “Because the boundaries are too narrow, the tolerances too big and false too easy,” one technician explained to us. “As soon as there was pressure on the rules on this subject, the producers would most likely start incorporating something and change the values. Then no one has more of it. One could then speak of manipulation. Or you could say, ‘I’m just using a different calibration. “

An example: some pressure sensors work in absolute numbers, some in relative numbers.

What you measure with a manual pressure gauge is the relative value. “If your sensor is absolutely measuring, you need to subtract something for the environment from the value,” says the expert. “Whether you pull more or less, it’s not wrong, it’s part of the process. But different results emerge. Therefore, the measuring system is not at a reliable technical level. ” Ducati chief designer Gigi Dall’Igna also criticizes this fact.

That the positions are so far apart has only gradually become clear to members of MSMA, Race Director Mike Webb and Technical Director Danny Aldridge since 2016. Apparently, officials once thought it would be easier to monitor and punish them.

As speed-up team manager, Luca Boscoscuro let Fabio Quartararo take the Moto2 victory in Motegi without objection due to a lack of 0.05 bar in the rear tire. But the great works do not let the officials dance around on their heads.

The issue remains sensitive. The manufacturers offered Michelin some time ago to make and monitor the printing themselves. Then there would be no discussion.

But Michelin apparently does not dare.

Because Michelin technicians cannot predict which tire pressure you should start with to end up within the tolerance of the minimum values ​​after the race. So Michelin passes the money on to the factories and the teams.

Such is the reality so far.

We asked Ing. Sebastian Risse from KTM to shed light on the complicated tire pressure problem.

Sebastian, the public now knows that these tire pressure sensors do not give reliable results. It is said that they can even be manipulated. Is it correct?

A motorcycle manufacturer may go to a supplier and say, “I would like a variant specifically for me.” The customer could then express certain special wishes and perhaps design one or the other a little differently.

These systems are not standardized or certified. Of course there is a “spec sheet” with a certain tolerance. But it’s sometimes very big. We are talking about plus / minus 0.175 bar. If you choose the right sensors, you can imagine what is going on in the box. Then you immediately got almost 0.2 bar.

SPEEDWEEK.com on Tuesday released tire pressure records from the Jerez race. Do all manufacturers get this list after the races?

I can not say anything about that. These are internal agreements from the producers’ association MSMA. There was certainly a requirement that these records be not shared with anyone. Nor should it be discussed.

Now the question arises, if no solution has been found since 2016, how can one then suddenly be conjured up at the start of the 2023 season?

Basically, it is not the case that everything is forbidden when it comes to tire pressure. You can easily get a fine if you do not follow Michelin’s recommendations and drive lower tire pressures than what they prescribe.

The problem is that the rules refer to tire pressure while driving in a race. And it’s hard to predict!

Is there a chance that the six plants will agree on a standard sensor over the next few months? That all teams push themselves to the limit is clear and understandable.

If a standard sensor for 2023 has been established and the manufacturer provides the appropriate support, we can well imagine that there will be a common solution.

But the race direction or the technical director must be able to check if something has been done to the sensor by a factory or a team. The electrical infrastructure must be such that nothing can be manipulated on the road between sensor and log-in.

If it works, it can work.

Nevertheless, the task for the teams is still difficult to predict the value of the tire pressure at the end of the race. But it’s the same for everyone.

Afterwards, each technician must decide for himself how much air he then makes in each direction.

Because one direction is technically critical in relation to regulations, because there are rules for a minimum tire pressure. On the other hand, the higher tire pressure is critical for the driver in terms of performance and safety. Not because the tire could burst, but because if the pressure is too high, there is a lack of grip and driving feel.

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