Tyre pressure had always changed from track to track and from practise to race if Pirelli sees that they can go lower without safety issues. Ideally the pressure should always be freed and chosen by the team. But pirelli made a minimum pressure rule when they had a lot of blowouts in Silverstone. Of course this limit should not exist and when pirelli sees that they can broaden the limits without risk of failure they do (righteously so). And indeed this year there are not many failures.
Some proof:
http://www.autosport.com/news/report.php/id/126008
Monza:
Several drivers complained about the pressures being too high at Spa last weekend, though no changes were made, and the feeling has been much the same at Monza.
But following analysis of the data from first and second practice on Friday, Pirelli has brought the pressures down.
The teams were originally given minimum pressures of 23.5 psi on the fronts and 21.5 psi for the rears.
That has now been reduced by 0.5 psi at the front and 1 psi at the rear, creating new minimum pressures of 23.0 and 20.5 psi respectively.
https://www.jamesallenonf1.com/2016/07/ ... it-matter/
Austria:
Speaking in Austria on Thursday, Jenson Button said that the tyre pressures for this weekend of 22PSI front and 19.5PSI rear were far too high.
Isola addressed this on Friday and said that the solution may be close: “It depends what we see in terms of starting running pressures, ” said Isola. “If we see consistent numbers then we might relax it a bit.
Different form practise to race and from race to race.
Final thoughts:
How are the mandatory tyre pressures set?
Pirelli receives data from all the teams from its running on the simulators at their factories ahead of the race weekend. They base the pressures for Friday running based on the worst case scenario, which is normally the faster cars.
Then after Friday practice they receive detailed telemetry data from the FIA from all the cars and that should correlate with the simulation data. If they see anomalies then they investigate. They can either lower or raise the pressures based on that Friday data.
On the older tracks, the ones where teams have extensive experience and more accurate simulations, the data is normally very accurate. On newer tracks it can see some variations.
Since the Russian GP this year, the FIA has had the ability to monitor tyre pressures and temperatures in real time and that has revealed that some of the cleverer teams have found ways to get around the rules.
“We’ll be happy to reduce the pressures if we are satisfied that teams are not manipulating the pressures and temperatures, ” said Isola.
So has you can see setting a minimum pressure is and artificial constriction to the car with only one purpose: safety.
So what is the worse here?
Having teams send fake data to make the rules more constrictive in a zone where your team has an advantage?
Or have the highest degree of freedom to setup your car as long as safety is due, therefore maximising the speed of every car to their design?
For me it is very very clear