Rain is usually the game-changing factor in F1. A car that usually underperforms in normal conditions can suddenly seem to have elevated its performance when things get wet, and the same was witnessed in a rainy Belgian GP when George Russell shocked everyone by qualifying second. The other drivers weren’t surprised because they know a relatively slow F1 car can perform better when it gets rainy. There are a couple of reasons behind this some of which are tiers, changing track conditions, and wet and dirty air. The whole explanation of this problem can be explained by analyzing how F1 cars are designed. The F1 engineers know that winning means squeezing every last ounce of speed from the regulations, the rules that govern the F1 car design, and if they can figure out how they can go faster by 0.1 miles faster than the other car that could mean a championship. But all their hard work gets washed away when it gets drippy outside. This is because the cars are engineered to have maximum performance at the limit of their grips. Water happens to drastically reduce the grip.


Grip is defined as the coefficient of friction between the surface of the tyre and the surface of the racetrack. This friction depends on an array of factors including the roughness of the track as well as the type, temperature and therefore behaviour of the tyre rubber. These factors ultimately affect the deformability and viscosity of the tyre rubber which along with the tyre’s hysteresis are key factors in the generation of grip. 

stress mechanisms that affect grip

Indentation->This is where the roughness of the road’s surface excites the rubber material. As tyre rubber is viscoelastic, it distorts and adapts to the texture of the road surface as it slides over it. Therefore, as the tread block strikes a bump in the road, it deforms, but due to the hysteresis of rubber, it does not immediately return to its original shape. This asymmetrical deformation of the rubber generates a reaction force which opposes slippage – in other words, it generates a friction force (grip).

Molecular Adhesion->This is where molecular interactions occur at the interface between the tyre rubber and the road surface which generates grip. Essentially, the molecular chains of rubber form bonds (or Van der Waals bonds) with the road surface. As the tyre continues to slide over the surface, these chains are stretched and the viscosity of the rubber resists deformation generating a friction force (grip) which opposes slippage. The band then breaks and forms again further on. In this way, the rubber’s molecular chains follow this cycle of stretching and breaking which creates visco-elastic work. This work effectively multiplies the amount of bonding energy by a factor which depends on the temperature of the rubber and the speed of slippage. 

This is the basic science behind the grip of the car on racetracks. Rubber tyers and Asphalt have a frictional coefficient of 0.9 in dry conditions. The slick or we Asphalt can take values 0.1 or lower. Rain removes much of the engineering advantage that the top cars have evened the field and puts pressure on the driver.


We could see how the rain-affected Russell’s performance in Belgium or Oncon’s win with Alpine in Hungary. Rain shifts the pressure to the driver because winning in the wet depends on the factors that car designers simply don’t have any control over, like the tyers. Every F1 team receives identical tyers from Pirelli. The rain tyers come in two types full wet and intermediate. Intermediate tyers have shallow tread groups which run from the centre to either edge of the tread and full wet tires have deeper grooves that crisscross dividing that tread into individual blocks.


hydroplaning is when a layer of water gets between the tire and the road preventing them from making contact and effectively dropping your grip to zero if that happens the car just goes on a slippery journey into the walls. The grooves in a tyre tread act as a passage to channel water out of the way letting that rubber make contact with the road and produce a grip. The groove on an intermediate F1 Tire can evacuate up to 30 litres of water per second when you’re going 300 kilometres per hour. These grooves are relatively shallow because interiors are designed for use on tracks that are just a little bit wet or in the process of drying, once those grooves are worn down an intermediate tire is pretty much just an ordinary slick tyre. They have a different compound and won’t be quite as good as regular tires but a car can use them on a dry track. F1’s wet tires however are different. The tread grooves are much deeper so they can evacuate up to 85 litres of water per second, but they don’t work on a dry track that’s because their tread blocks serve another purpose and that is creating heat. Water is a very effective coolant and that makes it hard to get tires up to temperature on a wet track. So the tread blocks on F1 wet tires move around on the road surface, they wiggle generating extra friction that raises their temperature, also means on a dry track wet tires overheat. you will sometimes see F1 drivers puddle hunting on a drying track driving through standing water to cool their tires. Now the other problem with the wet tires is that the Groove tread has a compromised coefficient of friction. It depends not only on the materials and their temperature but also on their texture. A typical patterned Tire in the wet can have a coefficient of friction as high as 0.4 but much better than a slick 0.1. But a pattern Tire only has a dry coefficient of friction at about 0.7 less than the Slicks 0.9.