Whether they are competing in a championship or racing casually, most people try to squeeze as much performance out of their karts as they possibly can. There are a few ways to do it, and one thing many newbies consider is using larger tires to make their racing kart faster.
Larger tires will make your kart accelerate faster but you will sacrifice top speed. Larger tires have more surface area than smaller ones, providing more grip and more traction. This means the engine uses less force to push the kart forward to reach the same speeds as if the tires were smaller.
It’s not always legal but varying your tire pressures can give you the same effect. There are also some other tricks you can use to make the tires faster, and below we’ll go into more detail about each one.
How Tire Size Affects Speed
The size of any tire has an effect on a vehicle’s speed. Due to the lightweight nature of go-karts, this effect is hugely exaggerated. Even changing the diameter of a kart tire by half an inch can make a big difference in the top speed of the kart.
Essentially by changing the size of the tires you are changing the surface area of the tire, which means you’re also increasing the amount of rubber that contacts the surface of the tarmac.
You might think that smaller tires will be faster. Logically it would make sense since smaller tires would weigh less than larger tires. In addition, the smaller tires would naturally be able to complete more rotations in any given time than larger tires.
However, this is actually not the case. Smaller tires are actually slower than larger tires. Smaller tires mean a smaller surface area is in contact with the tarmac, and this means less grip. In order to achieve the most grip you need as much of the rubber to be touching the ground as possible.
Larger tires are therefore the option to go for when it comes to improving the speed of your kart. The larger tires give you more grip and traction, and this is because they allow the power to be put down more evenly when the accelerator pedal is pressed. There is also less resistance during the acceleration phase as the axle does not need to work as hard to get the tires to move.
However, the larger tires will begin to cost you at the end of the straight. Top end speed is the sacrifice here as the extra surface area will begin to limit the speed of the tires. In order to achieve a higher top speed, you need the least amount of resistance possible.
Note here that we’re referring to grip mainly to mean the grip you want through the corners. This is what allows you to take corners fast with confidence you won’t slide off the track. By traction we’re referring to the ability of the car to get off the line, or to accelerate out of the corners. Both are often interchangeable terms, but for this article we find it helpful to treat them separately.
Why Larger Tires Make Racing Karts Faster
Using larger tires can be effective in making your kart faster around a racetrack. The larger tires will provide more grip and traction, which will be a huge advantage in karting. With a lack of long straights, it’s better to have better grip and cornering ability than a higher top speed.
A higher top speed would only be needed on race day if you need to overtake other karts. However, the issue with using smaller tires for the higher top speed is that you will be sacrificing your grip in the corners. This will ultimately make it more difficult to overtake other karts despite the speed advantage on the straights.
With other karts being faster in corners you will be spending 90% of the lap being slower than the other karts around you. In addition, you will need a mighty exit out of the last corner in order to keep up with the kart ahead before the speed advantage kicks in.
Tire Size Legality
It’s important to always check the rules of your championship before you make a change to the size of your tires. Some championships have restrictions and rules surrounding the tire sizes as it could give competitors an unfair advantage. Breaking these rules could lead to penalties or even disqualification. So, always do your research before you change your tire sizes.
In 2017 Formula 1 reintroduced different tire sizes. This is something we last saw in the early 1990s. Famous pictures and videos of Senna always showed his car with larger rear tires than front tires. These disappeared shortly after. They were reintroduced in order to improve the traction of the cars (which have no traction control systems).
Being rear wheel drive, the larger rear tires give the cars better traction under acceleration. It will therefore also naturally give the car more rear grip. However, the front wheels remain smaller as using the larger tires at the front would hinder the turning ability of the car. This setup allows the cars to corner at high speeds, when paired with the immense aerodynamics of modern F1 cars.
Drag racing cars often look very out of proportion. As you might have seen, they have gigantic rear tires and tiny front tires. This is cleverly designed by using the best of both worlds of tire sizes. Drag racers produce a massive amount of torque which is all sent to the rear wheels.
Using the large rear tires allows all of this power to be put down onto the tarmac very quickly. The large contact patch gives the car the grip and traction that it needs at the rear during the start of the race.
The tiny tires at the front are used in order to reduce the amount of resistance the between the wheels and the road. So, these tires have essentially no grip at all. Remember, they are trying to hit the fastest possible speed and therefore do not need any grip at the front of the car to turn.
Using Tire Pressures To Change The Size Of The Tire
If using different tire sizes is illegal in your championship, you can still get the same effect by simply adjusting your tire pressures. This still has a huge effect in karting since the tires are so small, so you’ll often see all of the drivers playing around with their tire pressures in between sessions.
It’s important to remember that lower tire pressures tend to give you more grip, and higher tire pressures usually give you less grip.It’s a bit more complicated than that, but that is the basic rule of thumb when it comes to tire pressures. In order to understand why this is the case, it can be helpful to think of tire pressures using the model of a balloon.
Higher Tire Pressures
If the balloon is fully inflated and you put it down on a flat surface it has less of its surface area contacting the ground. This is the same effect you see when you use smaller tires. This leads to less grip in the corners, but also less resistance and therefore a higher top speed.
Lower Tire Pressures
If the balloon is inflated halfway, it has more surface area touching the ground, as the balloon’s surface isn’t being stretched by the excess air. This is what happens when you use a larger tire, or when you use a lower tire pressure. This will give you more grip as there is more rubber touching the tarmac.
It gets complicated when you look at how long the tires take to heat up and for how long they provide their grip. Higher tire pressures (less grip) will heat up quicker and provide grip earlier in your run. The opposite is also true as lower tire pressures (more grip) will take longer to warm up and reach their optimum levels of grip.
Other Tire Tips And Tricks
Aside from varying your tire pressures and sizes, there are some other ways you can get more performance out of your tires, and the first is to pay attention to tire compounds.
Different tire compounds can be used to provide different amount of grip. Generally, there are three different compounds to choose from in karting and they are soft, medium, and hard tires. Not all championships or classes will allow you to choose different compounds though, so check your regulations as usual before you make any changes.
The softer tires will provide the most grip and they will also heat up the fastest. However, they will also be the least durable and will generally run out of tread the fastest. These are perfect for qualifying runs and short races.
Medium tires are the in-between option and will provide average grip and average durability. These are mostly used in junior class races. They will also be great to use in short to longer races.
Hard tires are the most durable but will also offer the least amount of grip. These tires can still provide grip at extremely low temperatures which makes them ideal for moist conditions, somewhere in between dry and wet.
You can use tire prep in order to soften your karting tires. Many people use this technique to improve the overall grip of their tires. However, this is illegal in most championships, so double check whether you are allowed to do it before you try this out.
Tire temperatures are very important factors for determining how much grip your kart has. These are mostly controlled by the tire pressures, along with your driving style. Tires do not provide grip when they are too cold or when they are too hot. This means that there is a very specific operating window where the tires provide the most grip.
How To Find The Optimal Tire Temperatures
In order to find this temperature window, you will need to do some testing. Set all your tire temperatures equally and drive as fast as you can. When your lap times reach their fastest time (before they begin to drop off due to overheating tires) you need to quickly pull into the pits and measure the PSI of all four tires.
Write down this number because it’s the ideal PSI that your tires need to be when they are hot. Remember, tires will always go up a couple of PSI when they are hot. Wait until the tires cool down completely and note down the PSI of all four tires again.
You’ll find your ideal hot PSI and the ideal cold PSI. You may need to make some adjustments to perfect the tires, but that’s what testing is all about. The perfect pressures will also change depending on the track and ambient weather conditions, so it’s a game of balancing many different factors in order to get the most grip out of your tires.
Larger tires do make your kart faster due to the larger amount of rubber touching the tarmac. Overall, this will give the kart more grip and traction at the cost of top speed. However, grip in the corners equals speed in the corners, which is usually the most important part of any race.
Using different tire sizes is illegal in some championships so the same effect can be achieved using different tire pressures. Lowering the tire pressures will give the kart more grip, and higher tire pressures will give the kart less grip. Other factors come into play too, but following this general rule is often enough to get extra performance out of your racing kart.