After the second afternoon of Rally Sweden was dominated by tyre strategies and the loss of studs on stages featuring more gravel than snow, AUTOSPORT spoke to Pirelli's motorsport manager Mario Isola about the challenge of running studded tyres in far from ideal conditions.
Q. What's happening to the tyres?
Mario Isola: I can say that we knew this afternoon was going to be the hardest section of the rally for the tyres. The stages were completely gravel and with a lot of stones. We can see some studs missing and some completely worn which means the surface was very hard.
Ford and Citroen made different strategies, Ford changed after the first stage this afternoon and Citroen after the second one. The difference in the stage times seems to favour Ford.
Q. Which is the bigger problem: the studs coming out or the studs being broken?
MI: It's half and half because they start to wear and after some kilometres in these conditions, you lose the body of the stud.
Q. When we were here last, in 2008, okay the tyre itself was narrower, but the stud retention was good when there was more gravel around. Are you surprised by the problems this year?
MI: Not so much, when we were here in 2008, the conditions were much warmer. Now it is very cold and the gravel is very hard. Most of the studs are coming from the inside of the tyre which would indicate they are coming out because of the wheelspin and the braking forces, rather than the lateral forces.
If the studs were coming out because of sliding, the studs would be missing on the outside of the tyre. I had no possibility to check the stages, but listening to the drivers, the road has been rough and difficult and I am not surprised at what has happened.
Last year, in Norway, we had cold weather, but we had a good ice base on the road and we had none of these problems. The tyres worked well there.
Q. Are you frustrated to hear the drivers saying the tyres are making the cars undriveable?
MI: Honestly not because everybody is on the same tyre. They have to manage this like the brakes and the engine. They make their own strategies to make it work. But equally, these tyres are not made for these conditions, but we can only work with what we have.