A two-day tyre test involving four teams comes to an end at Monza.

Four teams were on track on Tuesday for the first day of the test organised by Pirelli to work on 2026 tyre development. Despite having won the Grand Prix on Sunday, Max Verstappen was back in action along with Red Bull teammate Yuki Tsunoda, Aston Martin's reserve driver Felipe Drugovich, Williams' Carlos Sainz and Racing Bulls' Isack Hadjar.

The original plan was that Red Bull would be on track with Verstappen in the morning and Tsunoda in the afternoon, joined by Drugovich in the Aston Martin. However, with storms and heavy rain forecast for Wednesday morning, the schedule was changed.

After the morning session, Williams and Racing Bulls were ready to get through part of their programme ahead of schedule, running Sainz and Hadjar in the afternoon. Aston Martin and Williams ran modified versions of their current cars, the AMR25 and FW47 respectively, adapted to accept the prototype tyres. Red Bull used a mule car based on the 2023 RB19 and RB did the same with a VCARB01 from 2024.

The overall programme for the test is focussed on finalising what slick compounds to use for next season. In fact, the tyre construction was homologated on 1st September, as per the regulations.

The was the seventh organised by Pirelli so far this year to develop the new tyres which, while sticking with an 18 inch diameter are slightly narrower, by 25 mm at the front and 30 mm at the rear.

On Tuesday morning, the four-time world champion got through his programme, doing 59 laps before handing over to Tsunoda, who did 63 in the afternoon. Verstappen's best time was a 1:24.117, set on his 25th lap, while the Japanese driver posted a 1:23.'826 on his 30th lap. In the Aston Martin, Drugovich completed 118 laps over the course of the day, with a best time of 1:23.792 set on lap 37.

Sainz did 49 laps with a best time of 1:22.388 set on lap 30, while Hadjar completed 65 laps, his best being a 1:23.951 set on lap 41. However, the times have no comparative value as they are linked to the specific programme assigned to each driver.

All the teams tried the softest compounds in the range. RB and Williams ran the C4, C5 and C6, while Red Bull and Aston Martin also tried the C3.

The programme began with quick lap runs to see the pure performance levels of the various compounds, before switching to longer runs to check the level of degradation. Ambient temperature ranged from 22 degrees C and 27 degrees while the track varied between 24 degrees C and 40 degrees.

On Wednesday Sainz and Hadjar lapped in the afternoon, trying a version of the Intermediate tyres before switching back to the softer dry tyres from the Pirelli range.

The wet track, caused by the rain which fell throughout the morning, gave the chance to test in real-life conditions a solution for the Inters that had already been tested at Fiorano when the track was artificially dampened.

Wednesday's work, other than evaluating the best options for the C4, C5 and C6 compounds, thus also allowed for a deeper analysis of the crossover phase between intermediates and slicks.

Sainz completed 57 laps, with a best time of 1:22.'108 on lap 24, while Hadjar stopped the clock at 1:23.'825 on lap 30 of 56.

The ambient temperatures were within the range of 20 degrees C and 25 degrees, while the tarmac went from 27 degrees C to 32 degrees.

Adding in the laps completed on Tuesday the two days of testing saw Pirelli amass an overall total of 467 laps for a total of 2,705 kilometres (1,680 miles).

Wednesday's running was limited to the afternoon since, given the unfavourable weather forecast, the two teams involved had accepted bringing forward half a day of dry running to Tuesday.

Pirelli has nonetheless managed to collect the necessary data to proceed with the development of the slick compounds to be used next season, which will have to be homologated by December 15.

The slick tyre testing will return at the end of September to the Mugello circuit and then for two more days after the race weekend in Mexico City. In Italy the harder tyres from the range will be finalised while in Mexico the softer tyres will again be put to the test.

These dates are the last two on Pirelli's development calendar for 2025 and they will be followed by the usual end-of-season testing scheduled for December in Abu Dhabi.