The FIA and Formula 1 have enacted a plan to add interest to the second race of double-header weekends by changing the tyre compound choices between races.
As outlined last week by F1's managing director of motorsport Ross Brawn, the hope is that changing the combination of the three available compounds between the two weekends at the same venue will force teams to do more track running at the second event, and add some strategic interest to the race itself.
The previous proposal to spice up the second event of double-headers at the same circuits by adding a reversed-grid qualifying race was dropped after Mercedes refused to support it.
"There are two elements to the second weekend," Brawn told Autosport.
"There's making sure people run all weekend, as we don't want a very quiet Friday because they've got all the data they need.
"And the other aspect is, is there something we can do that will engage fans a little bit more at the second race because of a change?
"Something which the teams won't see as upsetting their competitive status within F1.
"It will be very small if it is, it will be something like tyre compounds or something of that sort, we'll see whether there's any scope to do something with it.
"If they have a different range of compounds available, they'll do some work."
After exploring the options it was decided not to make a change for the first double-header in Austria.
However it will happen at Silverstone, with the C1, C2, C3 combination used last year on hand for the British GP, followed by a switch to a softer range with the C2, C3 and C4 for the 70th Anniversary event on the following weekend.
In another change, the allocation for the Belgian GP has changed from the C1, C2, C3 used last year to C2, C3 and C4.
Both Austrian races will employ the C2, C3, C4 combination featured in 2019, as will Hungary and Italy. Spain remains with the C1, C2, C3 used last year.
Pirelli F1 boss Mario Isola said: "With so many variables at the start of this delayed season, and a flexible calendar that doesn't leave much time to react to changing circumstances, it was agreed with the teams, the promoter and the FIA to announce the compound nominations for the first eight races this year all together.
"As usual, these compounds have been chosen to best match the characteristics of the individual circuit and provide interesting opportunities for race strategy."
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