Why Tyre Pressures Are Crucial in Assetto Corsa Competizione

As a realistic GT3 simulator, Assetto Corsa Competizione naturally covers the full gamut of car set-up options. 

From bump stops, to spring rates; from wing levels to differential preload settings; Kunos Simulazioni’s official game of SRO’s GT World Challenge championships tests the skills of engineers and drivers alike.

But the most important set-up option, the one that reaps the largest amount of lap time if gotten right, is tyre pressure.

Optimum Tyre Pressures in Assetto Corsa Competizione

Assetto Corsa Competizione has had multiple different tyre models in its five-year reign as the top GT3 simulator, with each iteration featuring different optimal tyre pressure ranges.

For example, the 2020 DHE tyre model had an optimal range of between 27.3 and 27.8 PSI, while the DHD2 2019 tyre sat between 27.6 and 28.0 PSI.

The latest version of the DHE tyre model, introduced alongside the game’s v1.9 update, saw the optimal range altered to between 26.0 and 27.0 PSI for every class of car in ACC; a stark change from previous builds where GT4, GTC and TCX cars had different optimum values to the game’s flagship GT3 cars.

Assetto Corsa Competizione On-Screen Tyre Widget

To help judge when your tyre pressures are in the optimal zone, ACC has a handy tyre widget located in the bottom right of your screen while on track.

This shows both tyre temperature and pressure, with a visual indication as to how over or under-inflated your tyres are at any given moment.

Each tyre is made up of three blocks, with under-pressured tyres denoted by a sunken middle bar. Conversely, over-pressured tyres are shown by a raised middle bar - check out the images below for examples. When the three bars are lined up perfectly, you’re in the optimum pressure range.

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Tyre temperature is also displayed: blue indicates tyres are colder than optimum, green denotes optimum temperatures and orange and red show temperatures exceed the ideal range.

It goes without saying that you will achieve the best grip and lap time if all four tyres are green and at their optimal pressures. Hot tyres tend towards wheelspin, causing a vicious circle of decreasing grip and performance.

Temperature Range and Tyre Behaviour Post-v1.9

Since ACC’s v1.9 update, tyre behaviour has changed dramatically. Your car will behave differently depending on whether your tyres run at the lower or higher end of the optimum pressure range.

For example, if your pressures hover around 26.0 PSI across the rear axle then the tyres have more flex thanks to softer sidewalls, which makes feedback less precise. This can help turn the car into slower corners at the expense of imprecision in high-speed sections.

Conversely, higher pressures will stiffen the sidewalls and make your car stabler through faster corners. By balancing front and rear tyre pressures you can help tune the handling balance of your car depending on the track. 

If a track has a lot of slow-speed hairpins, for example, then operating at the lower end of the optimal pressure range would be more advantageous.  

Naturally, you want to keep all four tyres within the 80-90 C optimum temperature range while maintaining an eye on the inside/middle/outside temperature spread.

Ideally, keeping the inside and outside of each tyre within 10-15C of each other is advised, with your camber and toe settings having a huge effect on these values. In theory, this means unrealistic set-ups with maximum negative camber and toe-in settings will adversely affect tyre behaviour.

Outside of telemetry analysis, you can check the tyre temperature spread by heading back to the set-up screen after a run. Or, if you want an immediate look at the temperature spread, you can hit the Escape key mid-corner and view the last known tyre temperature reading.

How to Manage Tyre Pressures in Assetto Corsa Competizione

One way to help adjust tyre pressures is through set-up options like brake ducts, ABS, TC and brake balance.

For example, opening up the ducts (higher numbers) will help cool the brakes, which helps reduce the temperature of the tyre. This in turn will reduce the peak pressure of your rubber. 

Brake ducts should be adjusted to reflect the ambient temperatures of the track - something that becomes trickier in endurance races when weather conditions and ambient temperatures continuously change.

You can help manage the front-to-rear balance of tyre pressures by adjusting the brake balance too: move the balance forward if your rear tyres are overheating, and vice-versa. The effect is marginal but could make all the difference.

Increasing TC1 and TC2 settings can also help mitigate wheelspin and reduce tyre temperatures. Likewise, increasing ABS intervention will prevent brake locking and increase tyre life at the expense of longer braking distances.

To fine-tune your braking performance, why not try trophi.ai? It uses AI to analyse your virtual driving, offering helpful pointers on how you can be both faster and more consistent in sims like ACC and iRacing.

More Tyre Pressure Advice

Generally, for every one-centigrade increase in ambient temperature, adjust your tyre pressures downwards by 0.1 PSI (on the basis you’ve already found out the optimal pressures). Do the opposite as the ambient temperatures decrease.

GT3 cars in ACC have an advantage over the other car classes thanks to tyre warmers. This means GT3 tyres start off at optimum temperatures so pressures reach optimal levels within two or three laps (track-dependent, naturally).

GT4s, TCXs and GTC cars on the other hand don’t have tyre warmers, so it takes much longer to build temperatures and pressures and makes set-up optimisation a trickier prospect - despite significantly fewer set-up variables compared to GT3 cars.‍

Wet Tyres

Although many changes were implemented with dry tyres post-v1.9, ACC’s wet tyre behaviour remains unchanged.

The optimum pressure range for wet tyres lies between 29.5 and 31.0 PSI. This is a wider range to account for drying and worsening conditions out on-track and means you can be a little more gung-ho with your starting pressure settings.

The principles largely remain the same for adjusting dry tyre pressures; the goal is to keep your tyres in the optimal pressure range. Wet weather brings its own challenges, however, with a drying track leading to overheating of wet compounds.

In this case, find standing water to drive through; this will help cool the tyres and keep the pressures under control, thereby optimising grip for most of the time.