It is not a secret that karting, and especially go-kart racing is a complicated sport that is affected by many parameters that combine into a winning race. Today I would like to talk about one of the important things you have to check before pushing the gas into the first corner. This is of course the air pressure we set in our tires before the race.
The optimal air pressure for go-kart tires is in the range of 8 – 15 PSI (or 0.55 – 1.03 bars). Of course, it varies depending on the many parameters that we are going to describe in the following post.
How does air pressure affect the handling or top speed?
The tire pressures on your kart will directly affect the handling and top speed. Adjusting your tire pressures is one of the most important setup techniques that you need to learn if you want to be competitive in karting, and even if you’re looking to continue a career in racing.
Think back to an episode of Top Gear where they brought Sebastian Vettel in to drive in their “star in a reasonably priced car” section. The very first thing that Seb did before he even got into the car was check the tire pressures and adjusted them to his liking.
Now, the tire pressures that you need to use (and the pressures that will make you faster) will vary depending on a wide range of factors. We’ll get into that a bit later, but for now, here’s the basic concept behind how your tire pressures affect your car’s handling and top speed.
Lower tire pressures will give you more grip through the corners, but it will lead to a lower top speed. That’s because when the tires are under inflated, there is more rubber from the tire that is touching the tarmac. With the increased surface area of rubber making contact with the road, there will be more grip. That’s why racing cars have massive tires (especially the rear tires that need more grip with the acceleration forces being pushed through them).
If you increase the air pressure in your tires, there will be less contact between the rubber and the surface of the road. While this will give you less grip through corners, it will also give you less rolling resistance, which refers to how much resistance the tires have when turning. The result is a higher top speed and faster acceleration out of corners because less energy is needed to make the tires turn when going down the straight.
The best way to remember this is by thinking about a balloon. When there is less air in the balloon it will be underinflated, and pushing down on it will cause more of the balloon to touch the surface underneath it (it becomes flatter). However, if you put more air into the balloon, it will be firmer and there will be less surface area of the balloon touching the surface underneath it when you push down on it.
Does the wrong air pressure wear my tires faster?
If you have the incorrect tire pressures on your kart, it will affect the tire wear. If tire wear and tire temperature is something that’s important to your kart setup, then this is crucial to keep in mind!
We’ve established that lowering your tire pressures will deflate the tires and cause more of it to touch the tarmac. This will make them heat up faster, and also cause them to wear out much faster. This is especially true considering your cornering speeds will be much higher.
On the other hand, if you have more air in your tires, there is less rubber on the tarmac, which will cause your tires to heat up slower, and also suffer less wear. Tires that have more air are also less prone to overheating, so if you’re finding that your kart is sliding around a lot more towards the end of a session, try putting more air in the tires to counter the overheating that they are likely suffering from.
How to choose the optimal air pressure for each race?
When it comes to race day, you’re going to need to find the optimal tire pressures if you want to be fast. The tricky thing about tire pressures is that it’s not just about the track and your setup, it’s also about the weather! This means you can’t just use the tire pressures that you’ve been using previously.
Remember, adjusting your tire pressures will affect how quickly your tires heat up, and how quickly they overheat. If the temperatures are on the colder side, you want to lower the tire pressures so that they can build temperature quicker. If it’s a hot day, you probably want to increase the tire pressures to keep them from overheating towards the end of the session.
You also need to keep in mind that each tire works at a different rate. If there are more left hand corners than right hand corners, the left front tire will be working the hardest, and it will need the most grip. This means that you might need to start the left front with a slightly lower pressure.
Here’s a tip that a pro racing driver once gave me that helps, especially if you don’t have a fancy digital tire pressure gauge. Go out for a session and drive the wheels off the kart. As soon as you come back in and the tires are still hot, take your tire pressure gauge and reduce the pressures to the optimal “hot” temperature (for example 12.5 PSI). Then all you need to do is allow your tires to cool down. Before you head out on track again, check the PSI of all your tires and you’ll find that they are all different. Record these pressures and experiment from there (it’s normal if each tire is at a different pressure because they all work at different rates).
Tire pressures are one of the most important karting setup elements that you need to keep in mind. It’s not easy to find the perfect tire pressures, but with some practice and a feel for the kart, you can find them. The optimal tire pressures are normally between 8 and 15 PSI for cold tires.