Explained: Why McLaren Were Disqualified from the Las Vegas Grand Prix

What Happened in Las Vegas?

Following the 2025 Las Vegas Grand Prix, Lando Norris (who finished second on track) and Oscar Piastri (fourth) were both disqualified from the race results after post-race technical inspections revealed their cars violated Formula 1's strict plank wear regulations. The disqualifications promoted George Russell to second place and gave Kimi Antonelli his maiden F1 podium in third, while dramatically altering the championship standings with just two races remaining.

The FIA stewards found that both McLaren cars had exceeded the maximum permitted wear on their floor planks. Norris's car measured 8.88mm and 8.93mm at the rearmost skid blocks, while Piastri's showed even greater wear at 8.74mm—falling short of the mandatory 9mm minimum thickness. These measurements, taken at specific holes drilled into the plank for scrutineering purposes, revealed breaches ranging from 0.07mm to 0.26mm below the legal limit.

Despite McLaren's protests and their explanation citing unexpected porpoising during the race, the FIA stewards had no choice under the regulations but to disqualify both cars. The stewards explicitly noted they "strongly held the view that the breach was unintentional and that there was no deliberate attempt to circumvent the regulations," but emphasized that "there is no provision in the regulations or in precedent for any penalty other than disqualification."

Understanding the Skid Block and Plank Assembly

The plank assembly, often called the skid block, is a critical safety component mandated by F1's technical regulations. It consists of a wooden plank made from beech hardwood (Jabroc) that runs along the entire length of the car's floor, from the front to the rear. This plank must be exactly 10mm thick (with a tolerance of ±0.2mm) when new and measures 300mm wide at its widest point.

Embedded into this wooden plank are titanium skid blocks—metallic inserts strategically positioned at various points along the floor. These titanium components serve dual purposes: they protect the wooden plank from excessive wear at critical measurement points, and they create the dramatic sparks visible during night races when the car rides low to the ground and makes contact with the track surface. The sparks, while visually spectacular, are actually an indicator that the car is running extremely close to its minimum ride height limits.

Four 50mm diameter holes and two forward 80mm diameter holes are drilled into the plank at precisely specified locations. These holes serve as the official measurement points where FIA scrutineers insert gauges to check plank thickness after races. The regulations specify that the plank thickness must be measured at the peripheries of these designated holes, ensuring consistent and repeatable measurements across all cars and teams.

The 9mm Rule: Why It Exists and How It Works

The plank regulation was introduced in 1994 following the tragic deaths of Ayrton Senna and Roland Ratzenberger at Imola. The FIA implemented the plank as a mandatory component to prevent teams from running their cars at dangerously low ride heights, which could cause sudden loss of downforce and grip if the floor bottomed out on track irregularities or during high-speed compression.

While the plank must be 10mm thick when fitted to the car, the regulations acknowledge that some wear is inevitable during the course of a Grand Prix. Teams are therefore permitted up to 1mm of wear, establishing the minimum legal thickness at 9mm. This single millimeter of tolerance represents the difference between a legal car and disqualification—a margin so fine that even unintentional breaches due to unexpected track conditions can have devastating consequences.

The regulation serves a crucial safety function by preventing teams from optimizing their cars to run at ride heights so low that the floor could make sustained contact with the track surface. Running too low creates multiple risks: the car can lose aerodynamic stability if the floor strikes the ground at high speed, drivers can lose control if the plank drags and upsets the chassis balance, and the structural integrity of the floor assembly can be compromised by excessive forces and vibrations.

The Performance Trade-Off: Why Teams Push the Limits

Under the current ground effect regulations introduced in 2022, running cars as low to the ground as possible has become absolutely critical for competitive performance. The closer the floor sits to the track surface, the more efficiently the aerodynamic devices—particularly the front wing and rear diffuser—can generate downforce. Even a few millimeters of additional ride height can cost multiple tenths of a second per lap, making the difference between winning and mid-pack finishes.

This creates an inherent tension in modern F1: teams are incentivized to run their cars as low as physically possible to maximize performance, but they must carefully manage the risk of excessive plank wear that could lead to disqualification. Engineers must predict how much the plank will wear during a race based on circuit characteristics, expected loads, ride height settings, and even factors like left-hand versus right-hand corner bias (which can cause asymmetric wear patterns).

The Las Vegas Strip Circuit presented unique challenges that caught McLaren out. The track features multiple high-speed sections where downforce compresses the suspension, pushing the floor closer to the ground, combined with a bumpy street circuit surface that can cause unexpected bottoming. The circuit's layout includes predominantly left-hand corners, which led to greater wear on the right-hand side of McLaren's planks due to load transfer during cornering. McLaren reported that their cars experienced "significant and unexpected porpoising" during the race—a high-frequency bouncing phenomenon where the plank repeatedly strikes the track surface, accelerating wear beyond predicted levels.

The Measurement Process and Scrutineering

After each Grand Prix, the FIA Technical Delegate conducts random inspections of selected cars in parc fermé, where vehicles must remain untouched following the race. For plank measurements, scrutineers use precision gauges inserted into the designated measurement holes to determine the remaining thickness of the wooden plank at multiple points along its length.

The process is methodical and unambiguous. Scrutineers measure at the peripheries of each designated hole, recording the thickness at multiple points to account for any uneven wear patterns. If any single measurement point falls below the 9mm minimum threshold, the car is deemed non-compliant with technical regulations. There is no averaging of measurements, no allowance for measurement uncertainty, and no discretion for extenuating circumstances—the rule is absolute.

In McLaren's case, measurements revealed consistent failures across multiple points. Norris's car showed violations at the rear measurement points with readings of 8.88mm and 8.93mm, while Piastri's car measured as low as 8.74mm—a significant 0.26mm below the minimum. These measurements were taken approximately four hours after the race concluded, allowing sufficient time for the materials to cool and stabilize to eliminate any thermal expansion effects that might affect accuracy.

Historical Context: Rare But Not Unprecedented

Plank wear disqualifications have become increasingly common in recent seasons as teams push ever closer to the performance limits under ground effect regulations. The 2025 Las Vegas GP marks the latest in a series of high-profile exclusions that have affected multiple top teams and championship contenders.

The earliest precedent dates to 1994, the year the plank was introduced, when Michael Schumacher was disqualified from victory at the Belgian Grand Prix for excessive plank wear on his Benetton. That decision established the principle that no penalty other than disqualification is possible for this technical breach, regardless of whether the violation was intentional or the result of unexpected circumstances.

More recently, the 2023 United States Grand Prix saw both Lewis Hamilton and Charles Leclerc disqualified for the same infringement, with Hamilton losing second place and Leclerc sacrificing his sixth-place finish. The 2025 Chinese Grand Prix resulted in triple disqualifications affecting Hamilton, Leclerc, and Pierre Gasly, while Nico Hulkenberg also lost his points finish in Bahrain earlier this season. These incidents demonstrate that plank wear violations can affect any team, regardless of budget or technical sophistication, when they push the performance envelope too far.

McLaren's Explanation and the FIA Response

Following the disqualifications, McLaren issued a statement explaining that their cars had experienced "significant and unexpected porpoising, which had not been observed during practice sessions, resulting in excessive contact with the track." The team's analysis suggested that race conditions differed substantially from practice running, with fuel loads, tire degradation, and car setup all contributing to unexpected floor behavior during the 50-lap race.

Porpoising—the aerodynamic bouncing phenomenon that plagued teams when ground effect regulations were first introduced in 2022—causes the car to oscillate vertically at high frequency. When this occurs, the floor repeatedly strikes the track surface, dramatically accelerating plank wear beyond normal predictions. McLaren's engineers had not anticipated this level of porpoising based on their practice session data, leading to a miscalculation in their ride height settings and plank wear projections.

The FIA stewards acknowledged McLaren's explanation and explicitly stated they believed the breach was unintentional, with no evidence of deliberate rule circumvention. However, the stewards emphasized that the technical regulations provide no flexibility or discretion in these cases. Article 3.5.1 of the FIA Formula 1 Technical Regulations specifies the minimum plank thickness without exception, and decades of precedent have established that disqualification is the only permissible penalty, regardless of the cause or intent behind the violation.

Championship Implications and Moving Forward

The double disqualification delivered a significant blow to McLaren's championship ambitions. Norris's exclusion from second place cost him 18 points, reducing his championship lead from what would have been 42 points to just 24 points over both Max Verstappen and Oscar Piastri, who now sit tied on 366 points. Piastri's disqualification eliminated 12 points from his tally, mathematically complicating his own title challenge despite remaining in contention.

With the Qatar sprint weekend and Abu Dhabi season finale remaining, the championship battle has been dramatically reopened. A margin of 24 points—the equivalent of a win and fastest lap—can evaporate quickly in modern F1, particularly at circuits where McLaren may not hold the outright performance advantage they enjoyed through much of the season. The disqualifications have transformed what appeared to be a comfortable championship lead into a tense three-way fight requiring Norris to maintain consistency while his rivals capitalize on any opportunity.

McLaren has promised a thorough investigation into their Las Vegas plank wear issues to prevent future violations. The team faces a difficult challenge: they must continue running their cars low enough to maintain competitive performance, but with sufficient margin to account for unexpected race conditions that could accelerate plank wear. This may require sacrificing small amounts of lap time to ensure regulatory compliance, or developing more sophisticated predictive models that can anticipate phenomena like mid-race porpoising based on limited practice running.

The Bigger Picture: Technical Regulations in Modern F1

The Las Vegas disqualifications highlight the incredible precision required in modern Formula 1, where championship battles can be decided by measurements smaller than a human hair's width. The 1mm of permitted plank wear represents a vanishingly small tolerance when considered against the forces acting on an F1 car traveling at speeds exceeding 340 km/h while generating over 1000kg of downforce.

This incident also demonstrates the FIA's commitment to enforcing technical regulations without exception, regardless of championship implications or whether violations appear intentional. The consistency of enforcement—from Schumacher in 1994 through to multiple disqualifications in 2025—establishes clear boundaries that all teams must respect. While harsh for competitors caught out by unexpected conditions, this unwavering approach ensures competitive equity and prevents teams from claiming special circumstances to justify non-compliant cars.

As F1 heads to Qatar for the penultimate round of the 2025 season, every team will be reviewing their plank wear projections and ride height strategies with renewed scrutiny. The championship fight remains wide open not just due to on-track performance, but because a single technical infringement measured in fractions of millimeters can erase dozens of points in an instant. In modern Formula 1, the margins between triumph and disaster have never been finer.