Plank

A plank is a flat, rectangular piece of material attached to the bottom of a racing car that controls how low the car can sit to the ground and ensures all teams follow the same minimum ride height rules.

In motorsport, teams want their cars as close to the track as possible because this increases downforce, which helps the car grip the road and go faster through corners. However, running too low creates safety problems and gives an unfair advantage to teams with more money to spend on complex suspension systems. The plank solves both issues by acting as a physical barrier that prevents cars from running below a certain height.

The plank is also called a skid block because it literally skids along the track surface when the car bottoms out. You can often see sparks flying from Formula 1 cars during races—those sparks come from titanium skid plates attached to the bottom of the plank scraping against the asphalt at high speeds.

In Formula 1, the plank is made from a material called Permaglass, which is a strong, heat-resistant composite. When new, it measures 10 millimeters thick and runs along most of the car's underside. Earlier versions were made from wood-based materials like Jabroc, which combined beechwood layers with resin.

Racing officials strictly monitor plank wear throughout a race weekend. The plank can only wear down by 1 millimeter during competition—from its starting thickness of 10mm to a minimum of 9mm. After races, inspectors randomly select cars and measure the plank thickness at specific points using precise instruments.

If a car's plank has worn down more than the allowed amount, the driver faces disqualification regardless of where they finished. This happened to Lewis Hamilton and Charles Leclerc at the 2023 United States Grand Prix, where both drivers lost their race results due to excessive plank wear. Similar disqualifications occurred in 2025 when Hamilton was removed from the Chinese Grand Prix results and Nico Hulkenberg from Bahrain.

The plank rule creates interesting strategic challenges for teams. Engineers must balance running the car low enough to maximize performance while ensuring the plank doesn't wear too much over bumpy tracks or during long races. Track characteristics matter significantly—rough surfaces or circuits with many bumps cause more wear than smooth tracks.

While most commonly associated with Formula 1, planks appear in other racing series including Formula 2 and Formula 3. Each series has its own specifications, though the basic principle remains the same: controlling minimum ride height for safety and competitive fairness.