Setting tyre pressures is a daily struggle for drivers and mechanics. It contributes most to the kart’s behaviour and is affected by any changes on the kart. Most discussions in the paddock are held about the tiny nuances of tyre pressures and their differences. What should we consider when setting tyre pressures? 

Compounds

First of all, there is a variety of different manufacturers like Mojo, Vega, LeCont, Maxxis, MG, Komet etc that provide different tyre models and compounds. The compound of the tyre sets the basis for its behaviour. For example, Vega tyres are more round and have softer tyre walls. This makes them stick to the ground harder and often introduces the bouncing effect. While Mojo tyres have sharper edges, very firm tyre walls which makes them rather slide than bend and grab onto the surface. Also the different models of the same manufacturer have different compounds that all affect the behaviour and tyre pressures.

Tyre Pressure Basics

When we know the tyre we’re working with, the biggest influencers of tyre pressures are the conditions. The weather and the track conditions have a major impact on the tyre pressures. Low grip tracks that have not been driven on for a long time, or even just after rain, may need much higher tyre pressures to make the kart stick. The grip is always better on a layer of tyre rather than asphalt. When the grip conditions are good, the tyre pressures are dropped. This is also affected by air and track temperatures. Cold surfaces will take a lot of heating to lay some tyre down, while in hot weather the kart naturally wants to stick onto the ground. 

The heating depends largely on the asphalt type. Older asphalts get more abrasive over time, therfore, heat and damage the tyre more. While smooth and new asphalts are harder to grip up and require higher pressures to make the tyre stick. All of the basics are considered in the KartletiX free tyre pressure tool for the approximate pressure based on the conditions. Check it out on our platform to understand the differences. 

Kart Setup

The way of setting up the kart is another major factor that affects tyre pressures. Different rims are used with different karts and tyre models that influence tyre pressures due to its materials and air capacity. Magnesium and aluminium rims heat differently and, therefore, require different cold pressures. While most standard rims of the chassis manufacturers have similar air capacity, some special models have smaller capacities like OTK MXC and Freeline DM, for example. This decreases the volume of air within the tyre and contributes to different heating characteristics. 

Chassis setups play a big role in developing tyre pressures due to the softness or stiffness of the kart. While front width, caster and toe have little impact on tyre pressures, rear hubs and axle type modify both front and rear balance of the kart that works the tyre differently. Harder setup with longer hubs or stiffer axle works the tyre harder and requires lowering of the tyre pressures. At the same time shorter axle or hubs are easier on the tyres, which is also evident with reduced tyre wear, and need higher pressures to get there tyre up to the working temperature as quickly. KartletiX Tyre Pressure Tool Plus considers the factors mentioned above to personalise tyre pressures based on the chassis setup and make the predicted cold pressures even more accurate. 

Other Factors

There are more personalised factors to consider, like for example driving style. Not all drivers take the kart around the track the same way. Some are more aggressive and work the tyre more, others may be very gentle and maintain tyre temperatures for many more laps. And then there are total beginner drivers that barely get the tyres warmed up. They should have even higher tyre pressures to even make the kart stick and get the tyres up to temperature.

The difference in front and rear braking systems also have a little impact on the driving pressures. Firstly, the front brakes increase the tension on the front tyres. And secondly, the karts running with front brakes are usually heavier and more powerful. This all enables to drop tyre pressures once again. 

Some other tiny factors can come into play, like bad tyre sets that just don’t stick to the asphalt as well. Bad tyre sets are present in most patches, but they are very hard to identify, even when you’ve been to the track once. But since not all the tyres are the same, they shouldn’t be treated the same way either. KartTyre+ has added a unique option to take that into consideration. But you can learn from our 30 minutes of tyre courses within KartletiX PRO to be able to identify the faulty sets. 

The track conditions can easily be ruined by rental karts or motorbikes that sometimes want their track time between our free practice sessions. The different compounds, racing lines and sudden off-track excursions change the track dynamics completely for the next run. Many more laps need to be covered to reintroduce normal conditions. But what if it was a demo run between two official race sessions? Then you need to act accordingly and change your tyre pressures to get them up to temperature fast. These tiny aspects are also available on TPT Plus to avoid tripping up in such tricky situations. 

Wet Tyre Pressures

Wet tyres are dependant on much simpler conditions. Firstly, the age and type of asphalt set the basis for the tyre pressure. Secondly, we need to consider the amount of rubber on tarmac to determine the grip conditions. And thirdly, the amount of standing water determines how much working surface we need. All of this combined with the correct tyre compound model makes setting tyre pressures simple even in wet conditions. Although, the amplitude of the pressures is much bigger and doesn’t require quite as precise numeric results as in dry. And that’s exactly what TPT Plus is made for.

Hopefully this blog gave a much clearer insight to how many variables there are to consider to set tyre pressures. It can be the biggest struggle of the race weekend, but the mind-boggling worries can be left behind with TPT Plus that consideres all of the factors above. This development is a part of our biggest program, KartletiX PRO, to make racing life is easier for our biggest clients. But for those that can gather enough data from just the track conditions, the basic tyre pressure tool is available for free.