Analysis: Why Mercedes' tyre struggles might continue past Monaco
Mercedes returns to its Formula 1 factory in Brackley this week well aware it is under pressure to find the answers for the tyre 'mystery' that left it on the back foot against Ferrari at the Monaco Grand Prix.
Lewis Hamilton and his bosses were left baffled as to why they hit such trouble in Monte Carlo, when it struggled to get all its tyres performing in the right operating window for the crunch qualifying laps.
The situation resulted in Hamilton getting knocked out in Q2 and, although he staged a great recovery to finish seventh, Sebastian Vettel's victory allowed the Ferrari driver extend his title lead to 25 points.
But while Monaco is a unique on the calendar, Mercedes is well aware that this is not just a one-off problem, for there is some real urgency to get on top of the matter.
For the perfect storm of circumstances that hurts the team – using the ultrasoft tyre on slow speed corners at a track with a low abrasive surface – will repeat themselves in the forthcoming Canadian and Baku Grands Prix.
And if it does not come up with answers before then, things could be even worse.
The root problem
The core problem for Mercedes is trying to get the perfect balance with its tyres for qualifying laps, which means getting all four corners into the right temperature operating window.
Like Goldilocks and her porridge, F1 tyres cannot be too hot or too cold – they need to be just right.
With no high-energy corners in Monaco, it is especially hard to get the fronts up to temperature – and if the rear of the car is not well-planted then the danger is the rears overheat, especially on the surface.
Valtteri Bottas, who did manage to piece together a good qualifying lap to secure a spot on the second row, offered some fascinating insight into exactly why the situation for his team was so difficult in Monaco.
"We are struggling with the car nicely balanced especially in the very slow-speed corners," he explained.
"We are struggling with the rear stability and when the rear's not stable we are not putting energy through the fronts either because the fronts are not sliding. But when the rear's stable, the fronts are understeering slightly and that puts more temperature in the fronts.
"When you carry more speed through the corners you gain more temperature and energy in the tyres. For some reason Ferrari seems to have both of their axles, front and rear, always working but for us they're not really coming together both at the same time or not all the time."
Getting tyres into the right operating window is nothing new in Formula 1, but the situation this year has been made especially hard because of two factors.
One is that the tyres are less 'peaky' in performance, which means that it is hard for drivers to feel the point at which the tyres are producing their maximum grip.
So although there is in theory a wider operating window, the nature of the slow increase in grip – which is more a shallow curve than a sharp point – makes it hard to judge where the exact sweet spot is.
And to further compound the problem, the need to hit the jackpot with tyre grip is more important than ever before in F1 because the margins between cars are so small.
With a few tenths making the world of difference in the fight between Ferrari and Mercedes, falling out of the window is the difference between pole position and the second row.
Pirelli's F1 racing manager Mario Isola said in Monaco: "It is a bit of a characteristic of all the circuits with a low severity, because it is more difficult to warm the front tyres, and to have a front and rear that are balanced and able to generate the peak of grip. That was the case in Sochi – it was here."
It is on these low energy track that Ferrari's SF70H has proved to be more manageable and better able to perform in all conditions.
Speaking about Ferrari, Isola said: "I am not a vehicle dynamic expert but I think they have designed a car that is very good with the setup. They are able to find always a way to have a very balanced front and rear, and obviously this means performance.
"In the beginning of the year they were very good in race pace, but probably missing a little bit of top speed or qualifying performance. Now they also fix this, and the car is very well balanced."
The current situation Mercedes faces is different to what it experienced in Singapore 2015, when the team struggled all weekend to get its tyres to work at all.
However, there are similarities between Monaco and its struggles this year in Sochi – where on the ultrasoft, on a low grip, slow-speed track, it could not find the sweet spot again.
So Mercedes knows what needs to be done, it is just a matter of working out how best to achieve it. But time is short, as Monaco's headaches are the same as will be experienced in forthcoming races.
Isola added: "Sochi and Monte Carlo are circuits where you need a lot of traction and you have to protect the rear, but you cannot sacrifice the front too much.
"It is the secret of having a car that is very well balanced. Sliding from the rear can cause overheating, and it is a different overheating because of this smooth asphalt. And on the other side, you have to put some energy in the front tyres because otherwise you don't get the maximise grip.
"We will also have this effect in some other circuits like Montreal. It is something you are not going to experience in Silverstone in Spa probably because they have a different characteristics. Also the asphalt roughness is higher so you are able to generate more grip and putting more energy in the tyre."
Difficult to solve
The challenge of Montreal and Baku will be further increased though by the fact that they are tracks where teams runs with a lot less downforce, which could make things even harder for teams to get energy into their tyres.
As Force India's technical director Andrew Green said: "We've got to see where they [the tyres] go when you start taking the downforce off the car, which is something we've not really experimented with yet. It's going to be new for us - new for everybody, though.
"Traditionally Montreal is quite tricky. I think Baku will be a tough one. It's very smooth asphalt, very low energy input, a really long straight. It's going to be a big challenge for everybody."
Hamilton is well aware that Mercedes is under pressure to find the answers, if he is not going to have worse weekends than Monaco.
"It's definitely going to be a difficult one [to find a solution] and I really hope we get on top of it, because as soon as we get on top of those ultrasofts, then that puts us in a much better position to attack the other car," he said. "That's what we really need.
"Montreal has been a great hunting ground for me in the past and I plan for it to continue, so we are going to work very very hard over the next two weeks to make sure the car is in the right place to make sure we are ahead of those Ferraris."
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