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| Graph showing various strategies for a typical Grand Prix (Image: Toro Rosso) |
This graph shows the outcome of various strategies (lines of different colors) during a typical Grand Prix. The horizontal axis shows the number of laps of the race; while the vertical axis shows the time lost or gained in reference to zero which represents perfectly constant lap times. The blue line represents a two-stop strategy. The red line is a two-stopper while the green line shows the outcome of stopping four times.
During the opening laps, the driver gains time because the tires are new and offer more grip. Then, performance starts to decrease and the driver loses time. In green, he pits for the first time on lap 9. We can see that he loses 30 seconds during the pit stop. He comes back in the race, gains time again and stops for the second time on lap 21. And so forth. For this race, the best strategy (on paper) is the red, three-stopper. The worse thing to do is to stop twice (the blue line).
There's just one problem: ''Tire expectancy is not necessarily related to wear and tear. You can have a tire that loses only one tenth of a second every lap but cannot sustain more than 15 laps. Conversely, a tire that wears out three times faster might be able to complete 20 laps. It's very important to know the difference between tire expectancy and deterioration when devising race strategies'', he says.
The Monaco and Montreal tracks are historically those that change the most over the weekend. They are very dusty on Friday and increasingly grippier up to the race.
''Variations in tire expectancy and deterioration from Friday to Sunday have always been a part of the game in Formula 1'', Mékies continues.