Rain tyres - the secret of Bridgestone's success The British Grand Prix at Silverstone underlined the dominance of Bridgestone's tyres in the rain. Another victory for Michael Schumacher - the 60th of his Formula 1 career - and his Scuderia ...
Rain tyres - the secret of Bridgestone's success
The British Grand Prix at Silverstone underlined the dominance of Bridgestone's tyres in the rain. Another victory for Michael Schumacher - the 60th of his Formula 1 career - and his Scuderia Ferrari Marlboro team-mate Rubens Barrichello coming second place was only the beginning of the celebrations enjoyed by Bridgestone's teams. Lucky Strike B.A.R. Honda scored its first points of the season with magnificent 4th and 5th places for drivers Jacques Villeneuve and Olivier Panis. The day was rounded off with another point for Nick Heidfeld which helped move Sauber Petronas closer to 4th place in the constructors' championship.
Giancarlo Fisichella was the sixth driver on Bridgestone tyres in the top seven. Meanwhile, OrangeArrows driver Heinz-Harald Frentzen was able to chase a McLaren Mercedes after changing to Bridgestone intermediate tyres, having moved up to a potential points-scoring position from 16th on the grid. The competitiveness of Bridgestone's intermediate tyre, chosen by all its teams at the first pit stop, was clear for all to see
"The Bridgestones were simply flying" was the comment of one driver on the alternative brand. While the British Grand Prix was the only wet race of the season so far, there had been prior indications of the performance of Bridgestone's intermediate tyres, for example in free practice at the San Marino Grand Prix. However, it has not always been that way. Indeed, Bridgestone's poor showing in the DTM series race at Nürburgring, Germany in 1992 marked the final straw in what had been a lean period for the manufacturer's wet tyre performance going back to Formula 2 a decade earlier.
Hisao Suganuma, technical manager of Bridgestone's Formula 1 programme, explained: "The performance of our rain tyres at Nürburgring in 1992 can only be described as a disaster, we were seven-eight seconds slower than our rivals. We realised then that we had a lot of work to do and this was motivation enough to do better." From that point, the company's researchers and engineers at the technical centre in Japan began to analyse closely each part of the tyres' performance - construction, compound and pattern. The latter two appeared to have the most influence over the tyres' competitiveness, and by the next DTM race improvements had been made.
Not too much detail can be given about compound development since then, particularly in the company's Formula 1 wet tyres. In short, the way a rain tyre works depends on the chemical reaction between the rubber and water. In terms of pattern, development is about identifying the right land:sea ratio, that is the size of the contact patch between rubber and road (land) and the amount, depth and shape of grooves to drain water away (sea). Suganuma explained: "If one increases the sea ratio (the number of grooves), the blocks will be smaller which means there is less contact patch on the road. This causes more force to be put through the blocks which in turn causes more movement in the tyre. This can make the car feel unstable and ultimately make it slower.
"An intermediate tyre, designed to be used in damp conditions, has bigger blocks to increase the stiffness and make the tyre capable of going faster through corners. In this case, the sea ratio is decreased making the tyre less able to disperse water. Consequently, intermediate tyres are not appropriate when it is raining heavily or there is standing water on the track."
Despite having this knowledge, when Bridgestone first entered Formula 1 in 1997 the only way of proving its rain tyre performance was to design a pattern using existing technology in the laboratory and then track test it. However, this approach was advanced considerably with the introduction of Bridgestone's exclusive Hydro Simulation Technology. Using computer software, for the first time researchers were able to realistically simulate tyres travelling through water.
"We used this cutting edge technology to see what we could not see before with our eyes. From this information we were able to develop a pattern which efficiently disperses water and works in harmony with the compound," added Suganuma. The result is Formula 1 intermediate and wet tyres that look quite different to Bridgestone's competitor's tyres. The intermediates have vertical and lateral grooves which evacuate the water from the tyre as a whole, and small cuts called sipes that disperse the water from the individual blocks. Suganuma said: "We have worked hard to develop the best tyres for wet conditions that we can and I think yesterday demonstrated how that has paid off. Nonetheless, the work continues."