Kimi Raikkonen admitted Lotus was struggling to get the Pirelli tires in the right operating window during Canadian Grand Prix free practice on Friday.
Several teams had difficult getting the tires to perform in the cold conditions, and Raikkonen fears a poor qualifying performance if the situation does not improve for Saturday.
"Obviously the lap time was not the fastest but it's very close here between everybody, so if you go faster you can gain a lot of places," said Raikkonen after ending the day back in 11th. "The car is not too bad but we have some issue with getting the tires working. If we can get the tires to switch on, it makes a much bigger difference than any small setup thing.
"It's the same story as in Monaco. We were pretty OK but we were not fast enough in qualifying because of the tires not working. If we can get the tires working, it makes a massive difference."
He does not think there is anything else wrong with the car beyond the difficulty with tires.
"It's not too bad but the feeling is that if we can switch the tires on it will go better," Raikkonen said.