Ferrari driver Fernando Alonso has criticised Formula 1's tyres.
He says the Pirelli tyres "go off" too quickly to allow drivers to push to the limit throughout a race and are this year too hard to provide good grip.
The Spaniard, who finished fourth in Sunday's Monaco Grand Prix, said drivers had to back off within a few laps to make the tyres last whether they provided enough grip or not.
"They are too hard. There are no secrets," he said.
"When they bring normal tyres with good grip, we finish the tyre in two or three laps. When they bring harder tyres we finish the tyre in eight or nine laps but we go very slow."
The double world champion's criticisms echo those of other drivers this year - Force India's Sergio Perez said earlier this month that the harder tyres this year were "embarrassing" for F1 because the back-of-the grid cars were slower than the fastest GP2 support-race cars.
Alonso added: "This is what we have - it is the same for everybody. The tyre is what it is and what it has been for the last four years unfortunately."
Pirelli's remit when it came into F1 in 2011 was to provide tyres that degraded rapidly and forced teams to make at least two pit stops in a race.
This year the company has chosen to supply more conservative tyres because it was worried about the potential effect of the greater torque of the new turbo hybrid engines.
Paul Hembery, the Pirelli motorsport director, had a public row with Alonso at last year's Korean Grand Prix after the double world champion criticised the tyres.
Pirelli declined to comment on Alonso's latest criticism, saying: "Pirelli prefers not to reply to remarks which have not been made directly to us. The only direct comments we received so far are positive."