The only part of your car that touches the track is the tyres. This fact is carried across all of the cars in iRacing, regardless of whether you’re driving the latest F1 car or a Formula Vee. Some cars that are low downforce, like the majority of touring cars, are so reliant on this tyre-to-track contact that even minor setup changes can result in a huge difference in performance.
The Tyre Contact Patch
Inflating a tyre will cause it to expand until it reaches a point where it touches more or less the perfect pressure in terms of the size of the contact patch that’s presented to the track. Inflating it too much and the tyre surface moves from being flat, edge to edge, to more rounded in the centre. This, of course, reduces the contact patch’s size and your grip level on track.
Lowering the pressure below optimum has a similar result, with the centre of the tyre caving inwards, resulting in the tyre mainly touching the track with its outer edges and increasing friction, having adverse effects on temperature and wear.
The trick is to find the perfect pressure to maximise the contact patch and give you the highest possible grip level. However, this can be quite difficult and time-consuming to achieve and can be influenced by many factors.
How Does iRacing Display Tyre Pressures?
For most cars, iRacing doesn’t give you real-time tyre information while driving, so you need to pit to get this data. A common way to get your tyre pressures correct in iRacing is to drive a few laps using the default setup and pressures, enter the pits and check the temperatures.
Temperatures are displayed in PSI on three spots per tyre. For example, if you’re driving a GT3 car, you’ll get 12 temperature measurements: the front-left tyre will show O for Outer, M for Middle, and I for Inner, with individual temperatures per section.
Your aim when working on tyre pressures is to get the middle temperature to be more or less the same as the inner and outer measurement points. Lower temperatures in the middle are usually a sign of too low tire pressure, and the opposite if it’s higher. iRacing can display pressures and temperatures in either Metric or Imperial, though, but whatever your preference, the principle remains the same.
Delta Features For iRacing Tyres
Coach Dave Delta now has a brand new tyre temperature widget function for iRacing, built into its UI, that will show you temperatures of all four tyres through a lap, to help you decide in which direction the setup needs to go to combat tyre wear and temps.
Key Factors Affecting Tyres
Adjusting the camber angles – the angle between the vertical axis of the tyre and the vertical axis of the car – is vital when working on your tyre pressures in iRacing, as it can help even out the temperatures if you’re seeing higher readings on the inside of the tyre when compared to the outside. What you will realise is that tyre pressures and temperatures are directly intertwined – the greater your tyre temperature, the greater your tyre pressure.
Changing your driving style to be less aggressive with steering inputs can also help manage tyre temperatures with the added benefit of reducing tyre wear as well. If you are steering with too much intensity and at too large of an angle, your tyres will scrub across the track surface unnecessarily, increasing your pressures as a result.
Track temperature, of course, makes a massive difference in tyre temperature too. A good practice is to run lower initial tyre pressures on a hot track, with the tyre eventually warming up to reach its optimum pressure and contact patch after a couple of laps. The hot track causes the tyre to heat up faster than a cold track, so it’s essential to start with higher tyre pressures when racing on a cold track surface.
iRacing Telemetry
We have an excellent guide explaining the major points on how to set up and use Motec telemetry analysis in iRacing that should make it relatively easy for you to understand better what’s going on with your car that you may not be aware of.
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The iRacing Tyre Model
iRacing has been developing and improving its tyre model for years to make it as realistic as possible. However, not everything that works in real life translates 100% into iRacing. For example, with GT3 cars, running with very low tyre pressures can yield good results. This may seem counterintuitive, but that’s what works now and may change in the future – the iRacing tyre model is permanently evolving.
We recommended the following baseline settings for GT3 cars – setups for which you can purchase now as part of our iRacing setup subscription:
- Cold pressures in the pits: Minimum
- Hot pressures on track: 1.50-1.55 bar
- Hot temperatures: 80-90°C when driving on track
These are good settings to start from and will need minor adjustments depending on your car setup, track type, track temperature etc.
Recap and Final Thoughts
It’s important to level out your tyre temperatures by testing over a short stint and checking values in the pits. Camber angles, driving style and track temperature all play a big role in getting your tyres up to temperature and getting the resulting pressures correct.
It’s also important to run longer stints to understand how the tyre behaves under lower fuel levels as the fuel burns off, but with higher tyre wear levels. Consistent lap times and a smooth driving style yield better results in managing tyre wear and keeping your tyres within a good temperature window.
Tyre pressures and everything related to it is sometimes referred to in real-world racing as a “dark art”, and it’s similar in sim racing. The best way to understand how tyre pressures can make you go faster or slower, is to get out on track and use our guidelines to find out what works for you.
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