Carlos Sainz says it's "unfair" that some teams and drivers are getting early experience of Pirelli's bigger tyres for 2017.
Mercedes, Ferrari and Red Bull have produced test cars based on their 2015 machines to simulate the higher downforce and grip that will be produced next year.
"It seems unfair that there are drivers who already know what those tyres are like, and others who don't," Sainz, said.
He said he thinks Pirelli should have had enough data to "make a decent tyre for the first races and then develop it" after that. The Spaniard said he has asked Red Bull if he can join the team's forthcoming test in Abu Dhabi.
"I have offered to test in Abu Dhabi, because I will take any opportunity I can get. But maybe it's already a little too late," Sainz added.
He also spoke about the final three-race battle between Lewis Hamilton and Nico Rosberg for the title.
Sainz said: "Lewis still has a chance, although it's true that Nico is far ahead. But while you still have to fight, championships are never won."
Bahrain International Circuit - Winter testing
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