Lewis Hamilton led criticism of the tyres Formula One supplier Pirelli plans to introduce in 2021 after drivers had a chance to try them out during Friday's practice sessions for the Bahrain Grand Prix.
"I'm trying my hardest not to say anything," said the Briton, who equalled Michael Schumacher's record haul of seven world titles at the last race in Turkey.
"They've had two years now to develop a better tyre.
"From a driver point of view we're working with brands and partners who are at the forefront of technology, elevating and moving forwards and if you're going back after two years of development, I don't know what's happening.