How McLaren broke F1's plank wear rules in Las Vegas GP

In the aftermath of the Las Vegas Grand Prix, the usual post-race inspections revealed that both McLaren cars had fallen foul of Formula 1's restrictions on plank wear.

The cars of Lando Norris and Oscar Piastri had both demonstrated wear beyond the minimum thickness on the rearmost skid block, defined as 9mm by Formula 1's technical regulations. Given that the plank must be 10mm thick when fitted, this gives teams only 1mm of permissible wear through a grand prix.

Should a car fail to satisfy the 9mm minimum thickness at the end of the race, this is then considered a breach of the technical regulations – as such, the car is deemed illegal and thus the results will be thrown out. There are four 50mm holes drilled into the plank, which the scrutineers use to measure the level of wear.

With the current regulations, plank wear illegalities have been more common. Until 2023, the skid block regulations had prompted only two disqualifications - both in 1994, the year that the plank was introduced into F1. Michael Schumacher was disqualified from his win at the 1994 Belgian Grand Prix, while Olivier Panis lost his ninth-place finish at Estoril.

In 2023's United States Grand Prix, both Lewis Hamilton and Charles Leclerc (driving for Mercedes and Ferrari respectively at the time) were disqualified for surpassing the maximum plank wear limit. Hamilton then faced a second disqualification at this year's Chinese Grand Prix for the same infraction, while Nico Hulkenberg's 13th-place finish in Bahrain was also expunged for excessive skid wear.

The deletion of Hamilton and Leclerc's results in Austin two years ago was a key factor in redefining the format of sprint weekends, as parc ferme was reopened between the sprint race and qualifying. Limited practice time, and the nature of the current cars requiring low ride heights to operate effectively, made it difficult for teams to ascertain how much wear a plank was realistically likely to face.

Lando Norris, McLaren (Photo by: Simon Galloway / LAT Images via Getty Images)

McLaren's issue in Las Vegas, however, is a different scenario. Owing to the changeable conditions throughout the weekend, it was difficult to lock into a set-up that could cope with the wet conditions in qualifying and remain handy in the race. The circuit is also notoriously bumpy, exacerbating the difficulty of keeping the plank in check.

That being said, the other nine teams had no such issues with their plank wear, so it's hard to see this as anything other than McLaren having made an elementary set-up mistake with both cars. The curious aspect of this is that McLaren is generally considered to have developed its 2025 car around using more of the front skid block rather than the rear, which perhaps suggests that it shifted some of the balance backwards to find performance in Las Vegas.

The current F1 cars are stiffly sprung to ensure the floor remains at a static level to produce consistent levels of downforce, which means that it's difficult to damp out the effect of bumps on the road. Teams will plan their ride heights around that to ensure the plank wear meets their expectations, but there can be circumstantial influences: tyre wear, fuel load, and kerb strikes are chiefly among those mitigating factors.

At the end of the race, Norris had been asked to back off - with it stated on the radio that he'd ventured into an extreme fuel-save mode to make it to the chequered flag. But could McLaren have sensed that his plank was on the limit? Unless you have a sensor there, it would be impossible to know until the scrutineers get the measuring calipers into the hole...