Pirelli opts for small pressure rise

Several drivers, including world champion Lewis Hamilton, voiced concern on Thursday that a potential tyre pressure increase of 5psi was too much.

The figure of 5psi appears to have been born out of a comparison between tyre pressures used at last year's Belgian Grand Prix, which was 18psi front and rear, and the initial figure Pirelli suggested to teams of 23psi for the fronts and 22psi at the rear.

However, after releasing the first figure, Pirelli made two subsequent changes.

The first adjustment on Thursday afternoon was a move to 22psi and 21psi respectively.

On Friday morning, Pirelli said its official figure, which it traditionally submits to teams ahead of first practice on every weekend, was being revised to 21psi and 19.5psi.

That represents a 1psi increase to both fronts and rears compared to Spa and a 3psi and 1.5psi rise from last year's race at Monza.

A further change could happen after running in Friday practice has been completed.

The two revisions occurred because Pirelli had received more up-to-date data from the teams following the last race in Belgium.

It noticed that the loads on the tyres had increased compared to previous data, some of which goes back to last winter, as can be expected with the development of an F1 car over the course of a season.

Pirelli has changed the construction of the tyre for this season and along with the increased performance and loads on the tyres this term and the unique pressures the Monza track represents, a rise in tyre pressures was required.

AUTOSPORT understands that during first practice, a number of drivers ran tyre pressures in excess of the minimum requirement of 21psi in the fronts, with one driver running 23.5psi.