The 0.4mm that is hurting F1

Whether we like it or not, the story of the 2019 Formula 1 season is boiling down to tires. The inability for many teams to find the performance and heat window for this year’s Pirelli tire compounds has been an elusive hunt for six races so far and the only team who seems to have unlocked the narrow performance window has been Mercedes.

Now, we can mumble and gnash our teeth about the situation and to be perfectly honest, we’d be justified at some level. The year began with a huge narrative that Ferrari were the team to beat and even after being pummeled like a blacksmith’s anvil for five races, people in the press were still burping up reasons Ferrari might win in Monaco. You can see where the teeth-gnashing might be justified at some level.

Last year Pirelli brought a thinner tread to their tire compounds for a series of races and when they did, Mercedes responded very well. Perhaps they felt that the 2019 thin-treaded tires would benefit most of the teams but that hasn’t been the case and while most team bosses complain, Pirelli says they don’t understand what the complaining is about.

After another beating in Monaco, Autosport’s Jonathan Noble has done a very nice job of exploring the tire issues and wrote a terrific article unpacking the details.

“The tires of this season are quite different from the ones of last season,” Ferrari boss Mattia Binotto explained. “There is no blame, it is only a matter of fact. The main difference is that last year we had very good warm-up with the tires and we were all focused and concentrating on cooling the tires as much as we could to keep them working, because the lower the temperature the better the grip.

“The tires of this season are quite different in this respect. Warm-up [is] a lot more difficult and what we may call the window, the temperature target of when you have the best grip from the tires, in order to achieve it, you need to heat up the tires.”

As Jonathan points out, the 0.4mm tread was introduced to eliminate overheating and blistering and it does that by removing more rubber that would simply store heat and create issues.

“This action moved the working range a few degree towards higher temperature,” says Pirelli’s head of car racing, Mario Isola. “It is not changing the working window itself, because this is a function of the compound and the same compound has the same working window. But it is slightly higher now – so the tires are overheating less and you can use them on the higher side of the temperature.”

What Jonathan offered in the article was a nice graph showing the working temperatures in each compound from 2018 to 2019 and the differences. What Mr. Noble discovers is that the operating window moved up in whole or at least the top range moved up. The C3 compound, for example, has a range of 105-135C while the C5 is 85-115C.

The key here is that even within the stated ranges, there is around 20C difference but just getting into that window isn’t enough. There is a key temperature in within that 20C range that the tire works best. For the C5, you get inside 85-115C but it could be 98C that is the magic heat that unlocks the tire’s peak performance.

“When there is a championship like this one, when there is a window and you have 4/5/6 teams fighting for tenths of a second, it is not just staying in the window that is important,” says Isola. “It is important to find the peak of grip.

“You have a window on a flat part of the curve, where it generates the highest possible grip. And inside this window is somewhere with a bit more [performance]. When you are close you are always hunting for it and the drivers can feel it.”

In the old days, minimizing the heat and bringing the temperatures down to a window was the goal but this year, the teams have to work in reverse order—they have to bring the tire temps up to a certain peak range. Imagine trying to manage that over a weekend when qualifying is looking for a single lap and the race is looking for peak performance of 24 laps.

This has prompted teams to re-think their aerodynamics in order to create more downforce to generate heat in the front tires. When the cars showed up in Barcelona for testing, we admired Ferrari’s front wing designed to move the air away from the front tires and control the outwash. The power Ferrari engine and low drag meant better straight-line speed and hence the predictions of their competitive level against Mercedes.

What we discovered is that Mercedes did a masterful job of anticipating the rising heat versus reducing heat strategy of the tin-treaded tires and they chose to keep the air inside the wing and directed downward. Sure, they had more downforce than Ferrari and that cost them on the straights but they killed it in medium and slow speed corners and tire performance.

The cars are already designed from the leading edge of the front wing to the rear so it isn’t a simple as putting a higher downforce front wing on, that would upset the entire balance of the car.

Ferrari are struggling to load the front tires to generate heat and on tracks with long straights, the front tires will cool by 30-40C and that’s a disaster for Ferrari. Mercedes, on the other hand, has a higher downforce design and this allows them to trim out or add as needed to find the right amount to generate the correct heat the tires need to be at peak performance.

As Mr. Noble points out, Mercedes boss Toto Wolff is clear about the change in direction with their chassis. How do you marry your superior power unit with an evolving chassis to stay ahead of Pirelli’s changes?

“In the early days of the power unit regulations we had a car which was a low-drag fast car on the straights and carried with the might of the engine,” he explains. “Over the years, I think chassis and power unit have merged in order to extract the optimum lap time. Half that is that the engine is still impressive, but we were able to wrap a chassis around it that has more downforce, and more drag.

“We’re not the quickest car on the straight anymore, but we believe that this compromise between these two main blocks of performance works well for us.”

Jonathan predicts that Canada will be a race that offers the best chance to understand the tires but I am not holding my breath. The fact is, if the tires are this persnickety to get on top of, we’re doing it wrong. The tire shouldn’t be this large of an impact on the series in which only one team nails it and the others would have to design a new chassis in order to find competitive performance against them.

All credit to Mercedes, don’t get me wrong, but this should have been avoided in the regulation set long before we got here.

Hat Tip: Autosport