Following the tyre deflations in Spa and a very public outburst of Pirelli criticism from Sebastian Vettel, the opportunity for the teams to play fast and loose with tyre pressures is diminishing.
In response at the following Monza GP, Pirelli initially suggested recommended much higher tyre pressures to mitigate the risk of damage. This was to be a 4 Psi increment for the front tyres and 3 Psi on the rears.
Lewis Hamilton was critical of Pirelli’s recommendations claiming if enforced it would be a “disaster.”
“In terms of putting the pressures up, I don’t personally think it is the right way,” said the newly blond Hamilton on the Thursday. He added, “I don’t think any of us have tried five psi more in these tyres because they are not designed to have five psi more”.
Having been brought into line following his expletive laden outburst at the Belgian GP, Sebastian Vettel disagreed. “I think it is right for them [Pirelli] to be extreme and in terms of safety I think they are doing the right thing.”
The of course we had the drama following the race when it was revealed both Mercedes’ cars had been tested on the grid by the FIA, and tyres readings were under the final Pirelli recommended limits.
The stewards absolved Mercedes, suggesting the protocols used to do the measuring had not been properly set out and agreed with Pirelli.
Egg on the face for the FIA.
The result, Pirelli and the FIA have been sent away by the Monza stewards to agree protocols for the FIA to test tyre pressure. Whilst the detail of this has yet to emerge, Pirelli have revealed the tyre pressure recommendations for Singapore.
Last year the front tyre limits were set by Pirelli at 16 Psi on the front. This has been raised by two Psi to 18 and the rear tyres must be at least 17 Psi.
Pirelli raised the tyre pressures in Monza by 3 Psi when compared to 2014.
The level of wheel camber allowed has also been reduced by Pirelli from 2014. Last year 4.5 degrees were used on the front tyres and 3 degrees on the rear. This year those numbers will be respectively 3.75 and 2.5 degrees.
Paul Hembery commented, “We will define together with the FIA a more accurate approach, which gives the team more clarity about the rules to tire usage. It is important that we give the teams precise instructions and therefore avoid cases such as that of Mercedes at Monza and misunderstandings. “
This will happen later today and a new technical directive will be issued and circulated amongst the teams by the FIA.
The Pirelli specifications for heating the tyres remain the same: A dry tyre is to be heated for no more than three hours and the minimum temperature is 60 degrees with a maximum of 110 degrees.
I’m not sure I understand the logic here. They wanted to put the pressures up a fair bit in Monza as it is a high speed circuit with high tyre loading – that is fair enough. Singapore is much slower but surely as a street circuit there is much more risk of debris so again a higher pressure would surely reduce the likelyhood of damage? (Smaller contact patch)
Maybe someone with more technical knowledge can help me with this….
The report Pirelli gave for the failures at Spa, was to do with an exceedingly large number of ‘cuts’ on the tires. So how will raising the tire pressures prevent that from happening?
Great question!
Given Pirelli’s analysis of Spa, (pdf http://bit.ly/Spa_Analysis ), raising pressures seems unwarranted.
One technical theory is that higher pressures equals smaller footprints (amount of tire touching ground at any time). However, the change in footprint size would be very small, so technically it doesn’t make much sense.
Another technical reason may be that lower pressures enable the tread to flex to a greater depth into crevices in the ground surface (in asphalt cracks, seams, curb ripples, etc). This reason comes a little closer to making sense, but…
There may be better reasons for Pirelli’s actions that have not yet been made apparent.
The contact patch will be much larger anyway – given the big reductions in camber
@fortis96
Check out the Tiny URL link to AMuS web site especially photos #3 & 5-7 and #14-15. The others are worth looking at as well. http://tinyurl.com/ntgrheb
There is a theory, that the tyre wall is distorting, which is clearly seen in the photos. Two things are supposedly resulting. When the sidewall ‘ripples’, extreme stress is put on the junction area between the sidewall and the tread, causing it to de-laminate from the tyre carcass soon after. The other part to the theory, is that the rippled out part of the sidewall is hitting the kerb, again imparting huge stress to what is a relatively small part of the tyre structure/sidewall, when comparing it in total – picture 15. I don’t recall these same spec tyres failing when they were given a lateral hit on a wall at Monaco etc. Measurements on similar sized racing tyres, driven by a lower power engine, gave readings of 20 tonnes longitudinal force for straight line acceleration, and 30+ tonnes lateral during cornering, at racing speeds. So it would be quite easy to look at picture 15 and theorise that an impact on that kerb and others, could have easily been the cause of Vettel and Rosbergs’ problems.