Thinner Pirelli tread at Barcelona, Paul Ricard and Silverstone

For those events Pirelli will use tyres with a slightly thinner tread, in light of information learned during Barcelona testing.

The tread for the three races will be 0.4mm thinner, but Pirelli is confident that it won't impact performance.

There is also a weight reduction of around 1kg per set, which teams will have to take into account when they ballast their cars.

"We made a request to the FIA to have a slightly different tread thickness for three races," said Pirelli F1 boss Mario Isola.

"That's Barcelona, Silverstone and Paul Ricard.

"The reason for this request is that, in general, the new tarmac has a lot of grip, low wear, and low degradation.

"With a lot of grip, the lap time is improving a lot.

"We saw the lap times in Barcelona during the pre-season test was three seconds quicker than last year.

"But the point is that we keep a lot of rubber on the tyre, because with low wear, the tread is there, we are not wearing the tyre. And this means we have high temperatures in the compound.

"So to try to reduce the temperature a little bit, we asked for a small reduction in the tread thickness.

"We tested the solution last year, and in terms of performance or other consequences, they are almost transparent.

"Obviously the reason we stayed on the standard tyre for this year was in normal circumstances you wear the tyre, and if you don't have enough thickness, you wear the tyre too quickly."

Such changes for specific events are unusual, but not unprecedented.

Pirelli requested a thinner tread for Spa and Monza in both 2011 and 2012.

Meanwhile Force India's 2019 tyre test has been cancelled for logistical reasons.

It was provisionally scheduled for Shanghai immediately after the Chinese GP later this month.

Force India has instead been allocated an extra day of tyre testing at the post-race session in Barcelona in May, where it will now run two cars - one for standard 2018 running, and one for 2019 development.