Felipe Nasr says that getting tyres up to temperature without tyre blankets will prove to be difficult after he spent a day conducting development work for Pirelli.
Formula 1 is set to ban heating devices for tyres from 2015 and Williams reserve driver Nasr had his first experience of competing without tyre warmers in Bahrain.
"We worked on many new compounds and it was another productive day for me to learn the processes and feeling of driving a Formula 1 car, and I did quite a few miles," he said.
"Doing a tyre test means you can test the tyres to the extreme which was a good experience. I also got to experience the differences between different compounds and how they affect the car and the balance.
"Running a Formula 1 tyre when it hasn't been in a blanket was one of the most interesting things as it's very difficult to get them up to temperature, even in the Bahrain heat, it will be even more of a challenge at tracks such as Silverstone or Spa."
Each team will dedicate one day of testing in 2014 to tyre evaluation with Pirelli.