In Turkey, Lewis Hamilton made his only pit stop on lap 8, replacing rain tires with intermediate ones. At the finish line, the set of intermediate rubber on his car worn out almost to the slicks, but the chief strategist of Mercedes, James Wowles, said that the team had no doubt that the rubber would withstand.
The confidence of the team was added by the information collected about the work of rubber in similar conditions during last year’s German Grand Prix.
“If we are talking about slicks, we have a lot of experience working on past tracks. By analyzing the available information, we can predict how the tires will behave on the new track, says James Wowles. “But we don’t have that luxury with intermediate or rain tires. Yes, in some places we managed to drive several laps on a slightly wet track, but in order to properly understand the peculiarities of rubber, you need to work with it in stable wet conditions.
In recent years, the intermediate and rain tires have remained almost unchanged, so we could use the previously collected data, including at Hockenheim in 2019. It was this information that gave us an idea of what to expect from these tires in the race. We had a more or less clear idea of what pressure and temperature should be.
As the track dries up, the rubber layer on the surface begins to come off the intermediate tire. This process begins with canals designed to drain water, but since there is no water as such on the track, these canals are not needed. As a result, the intermediate tire gradually turns into slicks, which in their characteristics are similar to a very cold Soft, while the composition is rather tenacious and works. So there really is nothing wrong with the intermediate tires wearing out.
When a rider in a pit stop switches to intermediate tires, because they are warmed up with heating pads, they work very efficiently for several laps. However, the further performance of the rubber depends on wear and track conditions. Sometimes there are problems with the tires – this is what we saw on the cars of some rivals, but not all.
In terms of reliability, the tires are not subjected to such serious loads on the wet track. Of course, the tires have a tough time on the Turkish track, but the speed on wet asphalt does not come close to generating such loads that affect the tires on a dry track. Thus, we were confident that the tires would withstand, but if we found any problems, we would immediately react and call Lewis into the pits.
Our greatest concern was a possible rain in the last laps. On actual slicks, we could have serious problems. In the worst-case scenario that we calculated, it would rain when Lewis passed the first corner. He would then have to drive a whole circle in the rain, which would be a problem.
To avoid such a scenario, in the last laps, we suggested Lewis go to the pits. We were not worried that the tires would not hold up to the finish line, we were worried about possible rain, which, fortunately, never came. “
In qualifying in Turkey, the best result of Mercedes was only the sixth place of Lewis Hamilton. James Wowles explained why this is connected: “In the first session, when everyone was working with rain tires, we looked good compared to the others, but at the end of the session, under the red flags, the scale of the problems became clear.
Everyone had only one lap time to get the tires working. Max drove a circle very quickly relative to us, but we were not able to warm up the tires in one circle. When the difference between cars of different teams, instead of the usual several tenths, grows to several seconds, this is not due to the speed of the cars, but shows who managed to bring the tires into the operating range.
In the second part of the qualification, everyone again went to a long run on rain tires. We again lost two seconds to Verstappen – no difference with the ending of the first session.
In the qualifying finals, Lance Stroll followed exactly the same plan as we did – one lap on rain tires, then two quick laps in the intermediate ones, after which he was first. We lost five seconds to him.
If you go deeper into the reasons, it’s all about the energy that the tires receive from the rotation of the wheels and from the heat of the front and rear brakes. Tires cool off faster on wet roads and more energy needs to be generated to keep them in the optimum temperature range than is lost under these conditions.
Ultimately, the faster you go on certain sections of the track, the more energy and temperature you generate, but in conditions such as qualifying in Turkey, we were relatively far from the leaders and could not achieve the required speed.
We don’t build a car for such conditions. We design the car to perform well in the expected normal temperature range in both wet and dry conditions. Obviously, in Turkey we have run out of tools with which we could generate a higher tire temperature.
We do not have answers to all the questions, but we will definitely reconsider our approach so that in case of a repetition of such conditions, we will be ready for them. “