McLaren test driver Gary Paffett reckons Pirelli's tyres have made great strides since the first group test on the new rubber last winter, the Briton having focused on tyre work during the opening 2011 session at Valencia today.
The Woking team has chosen to wait until next week before hitting the track with its 2011 car, and is instead using this week's Valencia test to set benchmarks on Pirellis with the 2010 machine.
Paffett said there had been clear improvement in the Pirellis since the Abu Dhabi test in November.
"The car we ran today ought to allow us to get the right loadings on the Pirellis to understand how they behave," he said.
"The tyres have changed since we last ran them in Abu Dhabi last year, and they'll change again before the start of the season.
"Today was about trying to understand the tyres - we established a good baseline and then did some long runs. Happily, the wear issues we experienced in Abu Dhabi have definitely improved; we saw better wear patterns and fewer problems with the tyres.
He believes Pirelli is on course to succeed in its aim of encouraging better racing through a wider variation in tyre behaviour.
"It's useful to understand how the tyres go off, and how the balance changes once they do," Paffett said.
"The medium seems to last the longest and the super-soft the shortest, but that's exactly what you want from a tyre - and it should lead to different strategies once we start racing."