Mercedes and Ferrari have opted for slightly different tyre compound selections for next weekend's fifth round of the season in Spain.
Under revised 2016 regulations, tyre supplier Pirelli brings three compounds to each race, with drivers permitted free choice for 10 of their allocated 13 sets.
For the race at the Circuit de Barcelona-Catalunya, the Soft, Medium and Hard tyres will be used, the first time that the hardest compound has been taken to a Grand Prix in 2016.
Both Mercedes and Ferrari drivers will have only one set of the Hard tyres available, but Mercedes has opted for five sets of Mediums and seven Softs.
Coversely, Ferrari will have four sets of Mediums and eight sets of Soft tyres.
Each driver must use either the Hard or Medium compound for one stint of the Grand Prix, while one set of the Soft tyres will be put aside for use only in Q3.
Pirelli has also confirmed that it has commenced running of its 2017 prototype tyres, with Jean-Eric Vergne driving a Ferrari F14-T at Fiorano on Tuesday.
Pirelli is permitted to test next year's prototype tyres on either a 2013 or 2014 specification Formula 1 car.
Further running is set take place later this year with current cars fitted with 2017 prototype tyres, after the FIA's World Motor Sport Council rubber stamped Pirelli's request for 25 days of testing.