Formula One returns from its elongated summer break at one of the most spectacular circuits it visits all season but, for tyre supplier Pirelli, Spa-Francorchamps brings its own peculiar demands.
The last race before the enforced factory shutdown saw the teams visit the slowest permanent track on the calendar, at the Hungaroring, but the resumption takes them to one of the quickest of all. Pirelli is taking its hard and medium compounds – the two hardest options in its range - to the foothills of the Ardennes, as they should be perfectly suited to the high-energy demands of the circuit, with its rapid corners and fast compressions. The big compression at Eau Rouge subjects the front tyres to the highest vertical load of the season, some 1000 kilograms, while the longest lap of the season – at just over seven kilometres – sees the cars on full throttle for around 80 per cent of the time.
At high speeds, aggressive camber angles can cause blistering as heat builds up around the edges of the tyres, but teams are expected to comply with Pirelli's maximum recommended camber angles, which should help prevent this phenomenon.
“Spa is not only an epic circuit, but also one of the biggest challenges for our tyres all year,” Pirelli motorsport director Paul Hembery noted, “Mostly, this is because of the very high-energy loads that go all the way through the tyres, both vertically – due to the big compressions such as Eau Rouge – and also laterally at fast corners like Blanchimont. Often, the tyres are subjected to forces acting in different directions at the same time, which increases the work still further.
“Looking after the tyres is very important, particularly as it's such a long lap, [but] there are plenty of overtaking opportunities, and the blend of performance and durability offered by our nominated tyres should maximise those chances this weekend.”
Although the region's unpredictable weather conditions means that there is a good chance of the intermediate and full wet tyres being called into play over the course of the weekend, the variation in the lap means that starting from pole is not as important as it can be on other circuits. The performance gap between the hard and medium tyre is likely to be more than a second per lap, but last year's race saw plenty of variation in the choice of which tyre to start on. Whilst most drivers started on the medium tyre, Force India's Nico Hulkenberg started on the hard tyre and finished fourth with a two-stop strategy. The top two finishers – Jenson Button and Sebastian Vettel - both used a one-stop strategy, while the third-placed Kimi Raikkonen stopped twice.
“There are a very wide variety of possible strategies available at Spa, with plenty of time to be won and lost if the right tactics are chosen,” Hembery confirmed, “However, any strategy has to be very flexible, because it's the changing weather that often makes Spa such a fascinating race.
“The conditions can change extremely quickly, which then makes how the teams use the intermediate and wet tyres the key to success – as we have seen so often in the past. Both our wet-weather tyres have proved their performance over previous races; with the intermediate tyre in particular showing how well suited it is even to inconsistent and drying conditions.”