Tire pressures are so important to racing of all types, not just karts, and we want to give you a quick guide on how kart tire pressures work. We are going to cover testing to find your ideal tire pressures, and how different tire pressures affect your kart’s handling.
The right go-kart tire pressure to use varies a lot, but it’s typically within the 8-15 psi range (when cold). The specific tire pressure you should use will depend on a variety of factors, from the track surface and temperature to the characteristics of the specific tires you use.
There are many different variables to consider when it comes to tire pressures, but it can be quite an easy setup element to get right. Below, we discuss everything you need to know about correctly setting your go-kart tire pressures.
Why Are Kart Tire Pressures Important?
Kart tire pressures are important is because your tires are the only part of the kart that touches the road. They are what translates your actions into kart movements on the track, and the pressure of your tires greatly affects the handling of your kart overall.
Many people often mess around with their chassis setups because they are not happy with how their kart is handling. But sometimes it’s as simple as having the wrong tire pressures, so never overlook this small setup element!
If you take a close look at what the professionals do, they take it even further by adjusting each individual tire’s pressure depending on the circuit and the weather. Most beginner and many more experienced kart drivers will just have a standard setup for all 4 tires. Let’s dig into more about why tire pressures are so important for karting.
Kart Tire Pressure Basics
The general rule around tire pressures is that they have a specific operating window. This window is the pressure range (usually reported in psi – pounds per square inch – or occasionally bar) that will give your tires the perfect amount of grip.
Your tires have a ‘cold’ pressure reading and a ‘hot’ pressure reading. Your cold reading is when the tires are cool and have not been used yet. The hot reading is when you have just come off the circuit and your tires are warm from driving, as the friction generated with the track surface causes the tires to heat up.
Hot vs Cold
Your hot pressure reading will be a higher psi than the cold pressure reading, as pressure increases as temperature increases. So, let’s say that you are about to go out on track and you set your tire pressures to 10 psi all around. After 15 laps of driving you come into the pits and the first thing you do is take a reading with your tire pressure gauge.
Not only will your tire pressures be around 3 psi higher than their cold state, but you will also notice that all 4 tire pressures will give you different readings. We’ll go into the importance of this latter point in more detail later on, but for now let’s discuss how you can use this hot vs cold relationship to set the right tire pressures for your kart.
Higher Tire Pressures
Generally, higher tire pressures (11 psi and over) will give you more grip earlier on. They will heat up quicker and reach their optimum operating window much faster. This makes them ideal for qualifying runs where you won’t be driving on the limit consistently, but rather you’ll be looking for one flying lap at a time.
The disadvantage though is that these pressures will cause the tires to overheat quickly, and you will probably find them losing their grip after about 7 or 8 laps of consistently hard driving, depending on the tire. In addition, your tires will also be wearing out faster because of the overheating.
You also can’t take your tire pressures too high, otherwise the kart will become unstable as there is less tire contacting the track surface, as the tire begins to lose its shape. There is also a maximum allowed psi for safety reasons, which varies depending on the manufacturer.
Lower Tire Pressures
Lower tire pressures (under 11 psi) give you the opposite effect. These tires will take longer to heat up and reach their operating window. So, you might find that you are lacking grip for 5 or 6 laps before the tires really start to ‘switch on’ and offer you maximum grip.
This makes these pressures ideal for race conditions, as you will start to find your speed towards the middle and end of the race, rather than having your pace dropping off towards the end. It has to be said that driving on these cold tires at the start of a race can be difficult for beginners, so make sure you get plenty of practice!
I should add that different tire manufacturers have different operating windows, so the psi may vary from Dunlop tires to Mojo tires, for example. You can often find spreadsheets on manufacturers’ websites of recommended tire pressures based on different temperatures and compounds.
Tire compounds also have a slight effect on the tire pressures you should run them at. In general, harder tire compounds will require higher pressures than soft compounds. The same goes for wet tires, which are run at much higher pressures than dry compound tires.
KEY POINTS• Your kart’s tire pressures will greatly affect its handling
• Tire pressures increase as their temperatures increase
• The ideal pressure operating window of your tires will depend on the manufacturer and the compound
How Temperature Affects Tire Pressures
If you have done some tire pressure testing in the past, you may have noticed that your tire pressures fluctuate a lot between runs. This is because heat in the tires will cause the pressures to rise. This could be something as obvious as the tires being in the sun, or something as subtle as the ambient temperature rising around the circuit by a few degrees.
This is important because not only will your tire pressures rise as you drive you kart (due to the tires heating up from friction with the track surface), but as you progress throughout your race day, the ambient temperature around the track might change too, and the temperature of the tarmac on the racetrack will also rise as the sun shines down on the circuit.
So, if the temperatures are soaring throughout the day, you will want to keep your tire pressures slightly lower in their cold state to account for the fact that the pressures will naturally increase as the day gets hotter.
Or it might be the opposite, and it might be a cold and cloudy day, with the ambient temperature staying roughly the same. In this case, you’ll likely be adjusting your tire pressures accordingly throughout the day, and perhaps even running them a little higher from the start to account for the cooler overall temperature.
How Track Time Affects Your Kart’s Tire Pressures
As I mentioned earlier, you will need to adjust your tire pressures based on how long you are going to be running your kart for. Some sessions are shorter than others, and this affects how you should set up your tire pressures.
If you need your tires to get to work quickly and give you all of their grip for a short amount of time (such as during a qualifying run or short race), you will need to push your tire pressures up higher. This is ideal for qualifying and warmups where you can set your laps at your own pace and have time to cool your tires down in between laps.
If you are going into a sprint final, and you will be racing for 18 laps straight, you will want to set your tire pressures much lower than they were for qualifying. This will keep your tires in their ideal operating window for the entirety of the race, rather than overheating and losing their grip halfway through.
KEY POINTS• Your kart’s tire pressures are affected by their temperatures
• These can change as a result of the ambient conditions
• They can also change as you drive your kart out on track
Advanced Kart Tire Pressure Settings
As we know, each tire works differently on each circuit. For example, we know that the outside rear tire will be working the hardest of all the tires in the corners. So, if we have a clockwise circuit with more right turns than left turns, we know that the left rear tire will be working the hardest.
The Left Rear
This means that the left rear tire will be generating the most heat of all four tires and is most likely to overheat and lose grip first. So, we can adjust our tire pressures accordingly. The left rear tire will heat up the most throughout a lap, so we set its pressure to be the lowest when it’s cold to account for this.
The Right Rear
The second hottest tire on the kart will be the inside rear tire. This tire will be taking the force of the left hand turns and is also part of the driven wheels, so it will in general become really hot. This tire will have the second lowest cold pressure.
The Left Front
Next will be the left front. This is the outside tire once again, so it will be heating up more than the inside front tire will be. This is going to be a slightly lower pressure than the inside front tire. But also remember that your front tires will be cooler than the rear tires, so you will want to push their pressures up slightly higher.
The Right Front
Finally, the right front tire will be the coldest tire on the kart. You want to keep this tire pressure as the highest cold measurement because it needs to keep up its temperature with the rest of the tires even though it’s taking less of the load in the turns. If this tire becomes too cold, you will lose your front-end grip going into right-handed corners.
Go-Kart Tire Pressure Example
Let’s imagine you have just come off your last heat, which was 15 laps. You started this heat with 10 psi on both your rear tires and 10.5 psi on both your front tires. Your hot pressures as you came off the track were between 12 and 13 psi.
The tires switched on at around lap 4 or 5 and started to overheat a bit towards the end of the race, at around lap 14. The tires lasted pretty much the whole race, which is great, and they didn’t take too long to heat up. You had good grip throughout the race.
Next up is the main race, which is 18 laps. But this time you want to adjust your tire pressures according to how much use you get out of each one in order to balance the kart more and keep your grip levels stable throughout the race. This race is also 4 laps longer, so you will need your tires to last a bit longer than the previous heat.
These are example tire pressures we may be looking at for the next race:
- Front Right – 9.57 psi (coldest tire, highest pressure)
- Front Left – 9.28 psi
- Right Rear – 9.14 psi
- Left Rear – 8.85 psi (hottest tire, lowest pressure)
How To Find Your Ideal Go-Kart Tire Pressures
As with any setup element in karting, it is important to find what works for you when it comes to tire pressures. Your driving style will determine whether you can quickly get heat into your tires or whether your tires will overheat earlier than others.
It all depends on how smooth or aggressive your driving style is. That’s why it’s important to find your ideal tire pressures, rather than just copying from the driver next to you. Copying someone else can give you a good baseline to work with, but it might not work for you at all depending on the rest of your setup and your driving style.
Do Some Testing
The best thing to do is to take a full day of testing just to find your ideal tire pressures that work best for you. Be sure to start the day by noting down the weather conditions and, if you can, the track temperature. Having these reference points can be useful to you in the future.
Top Tip: Create a setup journal, as this allows you to track the changes you make to your kart and the effects of those changes for easy reference at future races
The goal for this test is not to try and set a personal best lap time, but rather to find out how your tire pressures are affecting your kart. Don’t push too hard, and try to be as consistent as possible. Also test different racing conditions, such as a mix of qualifying laps and full race distances.
The Process To Follow
Start with high tire pressures, for example 13 psi, and try to focus on when your tires reach their optimum grip and when they start to drop off. Use your lap times to identify exactly when this happens to the tires. This is where being a consistent driver becomes extremely useful, because it will be more obvious to spot your tire conditions in your lap times.
If you know that you can set your lap times all within 0.100 of each other, you will see an obvious decline in lap times when you have cold tires at the start of the session, and when your tires are overheating at the end of the session.
As soon as you come into the pits off the circuit, take your tire pressure measurements again in order to get a hot measurement. This will give you an idea of how much your pressures rise while out on track and under different driving conditions.
Keep Dropping Your Pressures
With each run drop the psi down by 1. Keep going lower with each run until you find the lowest pressures you can run on and still knock out consistent lap times. Remember, it might take longer to reach fast lap times, so it doesn’t automatically mean that those pressures are slower than before, as it can just be an issue of getting them up to temperature.
Once you have found that sweet spot for your cold psi measurement (it’s normally around 8-10 psi for most conditions). From there, go up by half a psi to see how that affects your lap times. This will allow you to fine-tune your pressures even further to find the ideal setup for your kart. Note down anything significant about each pressure setting, such as overall feel and when the grip picked up and dropped off.
Try to map this out for yourself in a simple way so that you can easily refer back to it in the future. This means that, when you are in the middle of a race weekend, all you need to do is check the temperature and you already know exactly what psi you want your tires to be on.
KEY POINTS• Your ideal kart tire pressures will depend on a lot of different factors
• Each individual tire will have an optimum starting pressure
• Do plenty of testing to find your kart’s ideal tire pressure setup
It might sound like a lot of information, but once you have done a bit of testing and played around with your tire pressures a bit, you will find what works for you. From there, it becomes easier to adjust them according to temperatures and track conditions.
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