Tyre conditions are more important than ever to Assetto Corsa since the recent 1.5 update, complemented by the 1.12 update. It also contains a helpful GUI app displaying accurate information you probably need to really understand what is going on with your car:
Unfortunately there is no (easily accessible) documentation about it, so I’ll try to summarize how it works.
The elements displayed are:
(1) Core temperature: Since version 1.3 each tyre has separate core and surface temperatures.
(2) Surface temperatures: The surface heats up and cools down faster compared to the core, additionally the model contains three values for IMO (inner, middle outer).
(3) Current pressure: The temperature of the tyres also influences the pressure, which again influences and the shape and behavior of a tyre.
(4) A color code for the current grip resulting of the precise temperature of the contact patch.
(5) Wear indicator: Dependent how and how long you drive, the tyre’s durability decreases.
(6) Tyre compound code: A short form of your current tyres. Usually you may choose between SM (Semlislicks) and ST (Street) on road cars, and e.g. S (soft), M (medium) or H (hard) for race cars slicks, but there are a lot other types. This is very important as your target values regarding temperatures and pressure will vary across the compounds.
(7) New in 1.12: Colored tyre pressure. Like the color code for the heat you now have green for good pressures. Blue = too low, Orange/Red = too hot.
#1 Wait, what app?
When you sit in your car, ready to go, move the mouse cursor to the right until the sidebar shows up:
Find the tyre symbol and click it, then the tyre app will appear on the screen. Drag it somewhere it doesn’t decrease your vision but you can easily spot it. Once it has a good position and size, click the pin so it can’t be accidentially dragged around and the opacity activates.
Although the colors are the most obvious things to see, I advice to take care of the tyres pressures first. Compounds, even cars and axis have different “optimal” pressures. If you are only a few psi away from that sweet spot, you will notably lose grip.
Quick entry: In the setup screen, you see and adjust the “cold” pressures. That means your tyres are as cold as the ambient temperature. Once you drove them for a few minutes, they will be “hot”, which vastly increases the pressures. Now you can watch the color in the app and judge if you need to modify the cold pressures.
Although I have the opinion that you shouldn’t touch the setup when starting out with AC or simracing (instead focus on basics and consistency before), tyre pressures might be the exception. Dependent on the default setup they can make a huge difference in laptimes, but also decide if the car is well handling or not. This is especially true for the street cars. Kunos uses the factory settings for their default cars, and those are optimized for fuel consumption and safety in the first place – and comparably low forces. For a race track visit – even as beginner – you can decrease the pressues by 4 or 5 psi without a doubt.
A little bit more advanced: You can also use the pressure to increase or decrease tyre heating. Go a bit below optimal pressure, and your tyres will heat up slightly better. The oppositve for higher pressures. The heating realation for sure is not over-exaggerated, but it is there. Find a good compromise for the given situation. In AC the pressure part is more important, so if you find your tyres too cold and are below optimum pressure, go for the latter and set it in a way the app gives your a blue-green color for pressure.
Also don’t be afraid to do all of this asymetrically. Many tracks won’t tax the inner tyres as much. The same for front and rear axis: Mix different pressures in the setup screen so your data is fine during the driving.
This is pretty easy to spot. Contact patch is green, you are fine. Blue: Too cold. Orange/Red: Too hot. For orientation, Aristotelis posted some numbers:
Be very careful when starting with cold tyres, any car is very, very different and dull then. Tyres also need several laps until they settle down to something stable regarding temperatures, don’t judge too quickly.
You will also notice that the core temperature is something more stable, while the surface temperature is changing very quickly – for example a tyre can overheat during one long corner. Don’t worry too much, it’s impossible to always hit perfect temperatures – but make sure you don’t go too long in cold or hot conditions.
What can be done to heat or cool tyres? Well, there are many tricks, but only few are easy. The most effective way on GT tyres is to choose the correct compound. Softs are happy very early, but tend to overheat. Use them when the ambient temperature is low enough and/or when you can’t get Mediums warm, and so on. Don’t hesitate to use Medium or even Hards, the difference in their performance is not that big.
Also make sure you don’t overheat tyres with sliding or locking brakes. Try not to overdrive very hot tyres, steer as smooth and little as possible.
#4 Hands on example: pressure adjustment
Let’s have a basic tutorial how to utilize the pressure app in order to get things working out better. For this I picked the Special Event “Back to the Future”, so we can have comparable settings with one click.
For this sequence, I picked some kind of “comfort” pace. Smooth driving that doesn’t really aim at the fastest lap, but allows me to drive consistently so we can see the results without having too much interferance of slips, spins and mistakes. This is basically the pace we would pick up in a race when it is more important find a rythm and to finish without mistakes.
Let’s start with the default setup:
When your Nismo dealer hands out the keys to your new GT-R, you can expect the tyres to have 30psi on all 4 wheels. If you instantly jump to Silverstone-international now, you will notice this isn’t perfect. Laptimes are between 1:12.578 and 1:13.037.
Remarkable is the front left wheel has way too much pressure due to all those high speed right handers. The rear left is stone cold, but has a bright and green 36 psi. Let’s just try to have this pressure on all 4 wheels by putting -4 psi to the FL and -1 psi to FR/RL:
Now we have asymetrical pressures at the beginning, but within 2 laps they are on spot on all around. I was quite faster now, but even more important: Confidence and consistency improved as well. Laptimes are between 1:12.239 and 1:12.534 now, only 0.295s difference between best and worst (compared to 0.459s with the default setup).
That should be all for the moment! Not as hard, mh? But please keep in mind this is highly dependent on car, track, ambient temperatures, tyre compound and driving style. Those pressures are now probably not bad for a fast lap, but also not perfect: They will change with risks taken, sharper and more aggressive driving and the use of Traction Control.
Well, if you want to go slightly beyond basics: We still have a really cold rear left tyre. 62° core isn’t exactly the 80-90° what a Semislick wants to have. Remember that low pressures heat up tyres slightly more? In the screenshots we can see that both 35 and 36psi are bright green. Maybe we can improve the setup by dropping the pressure below 35psi in order to get some temperature in exchange:
Yep, it worked. I even scored my best lap with 1:12.203 in this setup, but: You can also see that the front pressures are 37 psi, unlike the result before. Before we jump to the conclusion that the raised temperature in the rear is directly giving me a faster lap, I’d rather think it just felt better and more predictable so my comfort pace was higher. I’m not a machine and confidence in the car is a huge factor to the actual speed. But that doesn’t make the setup tweaks less important, right?
I picked this example because I believe both track and car is available without DLC. If I’m mistaken please let me know so I can find a different example. Also the track is too technical, we’d need something easier.
Tyres need love and attention – they connect your car to the road!
Even if you aren’t that much into numbers and setups, you should try to dive into the temps and pressures. It is absolutely worth it and might even change how enjoyable a car is. Your Abarth 500 Assetto Corse is oversteering way too much? Maybe your rears don’t get heat and therefore lack both, temperature and pressure. Add 4 psi and try again.