George Russell believes F1 is not ready to dispense with tyre warmers and says "there will be crashes" if the sport bans blankets from next season.
As part of its efforts to reduce its carbon footprint, Formula 1 is seeking to impose a ban on electric tyre blankets from 2024.
Despite the complexity of producing a tyre that would not require pre-warming, Pirelli has made progress with its product which was tested in Barcelona recently and which will be assessed again at a post-British Grand Prix test at Silverstone next month.
The proposed ban on blankets for next season will then face a final vote at the end of July involving Formula 1, the teams and the FIA.
But Russell, who tested Pirelli's blanket-free tyre in Barcelona last week along with Ferrari's Carlos Sainz and Charles Leclerc, believes the high temperatures and specific track features in Spain may have exaggerated the prototype tyre's performance.
"In hindsight, it probably wasn't tested in the right conditions at the right circuit," Russell explained.
"I think if you go to a circuit such as Barcelona, which is quite an aggressive Tarmac, it was 40-odd degree track temperature, fully rubbered from the race weekend.
"The tyres were very sketchy coming out of the pit lane, but by about Turn 5 on the out lap, it was at a respectable level.
"But if I compare that in contrast with the start of the year, when I did one run in Jerez in 10-degree track temperature, it was extremely difficult getting out of the pits.
"And if I'm being totally honest, I don't think we as a sport are at a position yet to bring these tyres into a racing scenario.
"I would be very concerned for all the mechanics in the pit lane during a pitstop, I'd be very concerned for the out lap from a race in cold conditions.
"There will be crashes, I have no doubt about it. And I think there's a lot of work, expense, development going into these tyres. I feel like that could be put elsewhere."
Leclerc echoed Russell's sentiment and call for more testing to be conducted to get a broader sense of the blanket-free product's true efficiency.
"I think it's too early," said the Ferrari driver. "And I don't have all the answers for now. I have to say that in the conditions that I had during the test, it was good, and it went well.
"But in lower temperatures, I don't know, I haven't tested these tyres in lower temperatures, and that's where the big question mark is.
"So very difficult to answer whether I will be happy to go [with the new tyres].
"I would like to maybe test those tyres in different conditions, and then see whether they are raceable in all conditions. But again, it was a positive test with the conditions that we've had in Barcelona."
Fernando Alonso experienced blanket-free tyres in IndyCar at Indianapolis. But the Spaniard believes F1 doesn't need to follow the same path.
"I think it depends on the tyre energy that you put on that specific circuit," said the Aston Martin driver. "I think Barcelona will help the tyres. Some other [places] it would make things very difficult.
"Indy, I think you put a lot of energy in the tyres immediately, and it was fine.
"Places like Monaco, or some others? I'm not a big fan of removing the blankets to be honest, and I don't see the reason why."
Keep up to date with all the F1 news via Facebook and Twitter
