Pirelli says this week's Barcelona test is set to confirm that drivers will be making two or three pit stops per grand prix this season, as the teams conduct their most accurate race simulations yet at the Spanish track.
All four Pirelli compounds have been available in the winter tests held so far, but for this week's Catalunya session only the hard and soft tires will be in use, as these compounds have been chosen as the selection for the first three grands prix of the season, making this the most representative test so far according to Pirelli's motorsport boss Paul Hembery.
"Having announced our compounds for the start of the year, most of the teams will concentrate on testing the hard and soft PZero tires," Hembery said. "We're expecting them to focus on long runs and race simulations, which should confirm the results we have previously extrapolated from our testing data: two or sometimes three pit stops at every race."
The likelihood of an increased number of pit stops in 2011 has been one of the key topics of the winter, with Pirelli deliberately designing its rubber with less longevity in the hope of spicing up the action through tire wear and strategic variety. But this move has drawn criticism from some drivers.
McLaren's Lewis Hamilton said at the previous test that the driving style required to make the Pirellis last through a stint was "like driving an out-lap – very slow and not particularly exciting. It lasted a little bit longer but it didn't feel like I was really racing the car."
Fernando Alonso has also argued that introducing too many pit stops will lead to chaotic races that penalize the top teams.
"From what we have seen so far, degradation is very significant, which means we will have races with lots of pit stops," the Ferrari driver said at a sponsor event last week. "I'm not keen on that because I think this increased uncertainty does not favor the strongest teams. It's as if in football, it was decided to have a penalty per team each half hour in which case Barcelona and Real Madrid would not be jumping for joy."
Hembery pointed out that low temperatures so far this winter had made testing conditions unrepresentative of likely grand prix weather. He suggested firm judgments about tire wear and pit stops could only be made if conditions warmed up for this week's test.
"Our last test in Barcelona was held in temperatures of just six degrees in the mornings, which didn't help to rubber the track in or gather the information necessary to base strategies on over the course of the season," he said. "We're hoping for warmer weather this week, although it's unlikely to be as warm as the temperatures we are expecting for the first race in Australia."
The Red Bull drivers have been more open to the change in strategy, with World Champion Sebastian Vettel admitting that three pit stops were likely, but intrigued rather than concerned by this.
"I think one stop is impossible and at this stage also two stops, so I think it will be a three- or four-stop race. I think it will make it very interesting," he said. "The question is if it is a good thing for us or a bad thing. It's hard to say now because obviously we have to get going first and see how the races unfold."
His teammate Mark Webber warned that tire performance in testing could be irrelevant when the season starts.
"This has happened in the past. Last year at Jerez with the Bridgestones doing long runs, we were thinking, 'Oh my God, we're going to be stopping every...' you know, then we get to the first races and drive around all day [on one set]," he said after the last test. "We need to go racing."
At present, though, he feels the Pirellis' characteristics are adding to the challenge for drivers.
The Barcelona test commences tomorrow, with the majority of teams running until Friday. But Williams, Mercedes, Ferrari and HRT will start a day later than their rivals on Wednesday and run through to Saturday instead.