Eli5 – F1 cars have smooth tyres for grip yet on a normal car this would be certain death. Why do smooth tyres give F1 cars more grip yet normal cars less grip?


Eli5 – F1 cars have smooth tyres for grip yet on a normal car this would be certain death. Why do smooth tyres give F1 cars more grip yet normal cars less grip?

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Smooth tires can give normal cars more grip as well… under ideal conditions. Add a bit of rainfall and when running over water it can struggle to find a way out from under the tire surface and easily hydroplane, losing traction entirely. Similarly things like sand and grit can cause trouble, and smooth tires are often fairly soft to conform to the road surface and increase traction but also quickly wear out. Normal cars cannot take pit stops to replace their tires every 60-120 km.

It’s down to weather, normal road cars need to able to perform in the wet and dry conditions and need grooves to disperse water, otherwise they will aquaplane.

When it gets wet in F1 they change to grooved tyres for the same reason

The larger the area of the contact patch, the greater the possible traction. Racing slicks maximize the contact area. The reason these are not used on consumer vehicles is that roads can be wet, whereas racing is only conducted under very controlled dry track conditions. Once you have water on the road surface, a thin layer of water can be trapped between the tire and the road surface, causing the tire to hydroplane. Tire treads are designed to channel and expel water to the sides of the tire in order to keep the tread blocks in contact with the road. This is a safety issue because day to day consumer driving conditions are not controlled the way that they are on a race track.

My car’s tires were worn down almost smooth when I bought it. Just a little bit of rain and stepping on the gas while driving 65mph caused the back end to break free from the pavement. Driving over a railroad crossing on a curve, even when dry, same thing happened. After getting new tires, I stopped losing grip.

If the surface is dry and not metal, a smooth tire will translate the torque into speed. With metal or wet pavement the torque causes wheel slip

For starters, smooth tires do not equate certain death. The main purpose the tread pattern on a tire serves is to provide a route for water to go through.What this means is that when a tire with a tread pattern rolls over a wet patch of road, it dislplaces and removes the water from the road’s surface, allowing it to have cleaner contact with the road and ultimately more grip under wet conditions. Tread patterns can also increase grip in low grip environments, as is the case with off road tires, where the grooves are bigger and the knobs on the tires sharper and taller, so that mud and dirt can be displaced much like water but also because the treads can dig into soft and loose ground and provide mechanical grip.

In a controlled racing environment however, grip is essential, and the larger the contact patch of the tire the more grip you have, mainly due to the ability to moderate heat better. There’s actually a lot that plays into the overall grip of a tire and not just size but I don’t want to get into it and digress. However it is worth noting that even in racing use, when the weather is bad and the track is wet, grooved tires are also used.

The important thing here is that using a smooth tire on a wet road can lead to what is called hydroplaning, where the tire has no way to remove water from the road surface other than pushing it to the side as it rolls over the road, much like the bow wave of a ship. However this creates the possibility that water is trapped momentarily between the tire and the road surface, which reduces grip significantly and the driver has very little control of the direction of the car. For this reason in most jurisdictions it’s illegal to use “slick” tires on public roads and road legal tires have to have at least some amount of grooves to remove water. What that means is that if you see a smooth tire on a vehicle out on the road, it’s either someone using slicks illegally (unlikely, they’re very expensive and have very low mileage capabilities), or it’s a tire that used to have grooves but has worn down to the point of being smooth, in which case it’s very dangerous since it’s old and worn through, has no ability to remove water, has lost its elasticity over time so it’s harder as well as having worn through the usable part of the tire which means that the internal liners may start coming into contact with the road and that provides very little grip and also the tire may just burst after a point.

**TL;DR** Smooth tires that used to be grooved are certain death. Slick tires are not certain death.