Pirelli has confirmed the tyre testing schedule for the three in-season tests. The rules require each team to devote one of its six precious days to working for the Italian company.
The significance of the timing is that in theory when a team is tyre testing it is not working on developing its car.
In addition there is a test in Abu Dhabi at the end of the year when all teams will run the 2015 tyres.
The schedule is as follows:
Bahrain test (8-9 April)
Day1: CATERHAM
Day2: MERCEDES and WILLIAMS
Barcelona test (13-14 May)
Day1: SAUBER and TORO ROSSO
Day2: McLAREN and FORCE INDIA
Silverstone test (8-9 July)
Day1: FERRARI and LOTUS
Day2: RED BULL and MARUSSIA
Adam Cooper F1 
How were the teams assigned to the dates – did they have an opportunity to express a preference? I don’t suppose that we will know whether they will be working on refinements to the 2014 tyres or doing early work for 2015. I guess it will depend if the tyres perform as expected in the early races.