The only part of your car that touches the track is the tires. 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 tire-to-track contact that even minor setup changes can result in a huge difference in performance.
The tire contact patch and pressure relationship
Inflating a tire 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 tire 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 tire caving inwards, resulting in the tire 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 tire pressures?
For most cars, iRacing doesn’t give you real-time tire information while driving, so you need to pit to get this data. A common way to get your tire 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 tire. For example, if you’re driving a GT3 car, you’ll get 12 temperature measurements: the front-left tire will show O for Outer, M for Middle, and I for Inner, with individual temperatures per section.
Your aim when working on tire 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.
Key factors affecting tire pressures
Adjusting the camber angles – the angle between the vertical axis of the tire and the vertical axis of the car – is vital when working on your tire pressures in iRacing, as it can help even out the temperatures if you’re seeing higher readings on the inside of the tire when compared to the outside. What you will realise is that tire pressures and temperatures are directly intertwined – the greater your tire temperature, the greater your tire pressure.
Changing your driving style to be less aggressive with steering inputs can also help manage tire temperatures with the added benefit of reducing tire wear as well. If you are steering with too much intensity and at too large of an angle, your tires will scrub across the track surface unnecessarily, increasing your pressures as a result.
Track temperature, of course, makes a massive difference in tire temperature too. A good practice is to run lower initial tire pressures on a hot track, with the tire eventually warming up to reach its optimum pressure and contact patch after a couple of laps. The hot track causes the tire to heat up faster than a cold track, so it’s essential to start with higher tire pressures when racing on a cold track surface.
Telemetry
iRacing supports telemetry analysis via Motec or Mclaren Atlas software. This data analysis can be complicated for beginners, but it is the best way to determine exactly what’s happening to your tires. You’ll be able to see exactly where you’re overheating the tires on the track and most likely what’s causing it.
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.
Our driver coaches and car setup packages can help with this since Motec data is supplied with our setups. That, combined with our professional driver coaches, should get you up to speed quickly and give you a better understanding of how tire pressures work and how you can use our Motec data to go faster.
The iRacing tire model
iRacing has been developing and improving its tire 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 tire pressures can yield good results. This may seem counterintuitive, but that’s what works now and may change in the future – the iRacing tire model is permanently evolving.
A newer and far more realistic iRacing tire model is expected soon, along with rain at some point in 2023 that should change everything.
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 tire 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 tires up to temperature and getting the resulting pressures correct.
It’s also important to run longer stints to understand how the tire behaves under lower fuel levels as the fuel burns off, but with higher tire wear levels. Consistent lap times and a smooth driving style yield better results in managing tire wear and keeping your tires within a good temperature window.
tire 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 tire pressures can make you go faster or slower works is to get out on track and use our guidelines to find out what works for you.
