Real Data?


Yep, we’re going to make it three articles in less than a month regarding the tire physics in Assetto Corsa.

Dating back to the title’s original release on Steam’s Early Access platform in the fall of 2013, a big selling point of Assetto Corsa one which captivated many sim racers across the community – were the claims Kunos Simulazioni had made in regards to how each car had been developed. Assetto Corsa was said to stray from the formula that allowed enormous car counts in both Gran Turismo and Forza, instead focusing on real data to ensure the driving experience of each and every car was as authentic as possible. Even though the double digit vehicle roster was overshadowed by both triple and quadruple digit lists found in the mainstream car collecting titles, the lack of diversity was allegedly a trade-off for the most accurate physics ever seen in a consumer racing simulator. And for a period of time, many of us believed them. Virtual lap times were fairly accurate, setup techniques mirrored what had been occurring on the real race track, and the game was for the most part a genuine pleasure to drive.

But of course, people started finding shit. Third party modding teams in the process of building open wheel cars for Assetto Corsa began running into physics engine issues, with rumors of Kunos personally calling them and requesting the teams to keep quiet about obvious shortcomings on the official forums, which had once been an open resource for discussions. Individuals curious about how Kunos were able to pump out DLC packages featuring brand new GT3 cars so quickly ended up discovering many key components and unique geometries of certain cars had been hastily copied and pasted from one vehicle to another. Certain work-in-progress mods that were once advertised as a free download from a talented sim racer would disappear without any explanation given, only to resurface as official Kunos content in a future paid downloadable package. Slowly but surely, the smoke and mirrors show Kunos once used to push Assetto Corsa as the definitive PC racing simulator began to fade away, revealing a product vastly different than what their marketing department had described.


Two weeks ago, I penned a pretty basic article discussing something that your average Assetto Corsa player might not know about in regards to car setup – Optimal Tire Pressures. Despite all of the hype surrounding Assetto Corsa’s continuously evolving and highly complex tire model – which will be updated to Version 10 in the coming weeks – the internal files for each car told a much different story. Busting open the tyres.ini file for any car residing within your Assetto Corsa folder allows you to hunt down a value labelled PRESSURE_IDEAL, and this number dictates the exact air pressure you want in your tires while the car is turning laps on track, as it’ll help you achieve the maximum grip possible from each tire.

It’s not rocket science by any stretch of the imagination, and most modders already knew about this, so it’s not exactly a revelation either, but what it did do was significantly cut down on the amount of time spent fiddling with tire pressures in the garage menu. If a car’s ideal pressure was 33 PSI, you worked backwards and adjusted your cold pressures inside the setup menu to ensure once the tires would warm up from driving, it would hit exactly 33 PSI. I’m aware there are a few third party setup applications that convey this info in a much more user friendly manner, but at it’s core, it’s equivalent to looking up the answers in the back of your math text book. Forget about feel, forget about heat cycles, forget about anything you’ve learned from watching real life auto racing and how teams find the right pressures to run for each track, just look up this number and adjust accordingly.


So during my afternoon spent decrypting the content in Assetto Corsa created by Kunos Simulazioni themselves, and building a mini database for the article, I discovered that all GT3 cars in the game – regardless of the year they first hit the track – essentially ran a spec tire that used 33 PSI as the ideal pressure value. And I didn’t really have a problem with this, as it ensured fairness among all the cars. Sure, the cold setting was definitely on the edge of what both Michelin and Pirelli suggested to be safe values, but I can’t exactly get mad at a single PSI difference. However, this was only one piece of the puzzle. Pirelli and Michelin gave us the minimum value to ensure a customer’s safety. Nowhere on their website did it list an ideal operating pressure for their respective racing slicks, so naturally I assumed Kunos must have gotten this magic 33 PSI number straight from a GT3 team – falling in line with their whole “we use real data for each car” thing.

I was pretty shocked when I hit up the team manager of GAINESCO/Bob Stallings Racing Terry Wilbert, and received a much different value.

tire pressure.jpg

A one or two PSI difference between a modern PC simulator and the real thing is fine, as even the most advanced computer software can’t replicate everything down to the final near-insignificant detail, but a 7 PSI difference is way off the mark for a simulator which has claimed to use real world data. And obviously, there are questions which arise from this discovery. I don’t doubt that Kunos Simulazioni obtained legitimate data for some of the cars featured in Assetto Corsa, but this is a pretty big gap.

So I’d like to know what’s going on here, and obviously I’ll leave this up to the readers of to discuss. It really wasn’t all that difficult to pick a North American GT3 team at random from the most recent set of results, visit their website, find an email address from somebody vaguely related to the team, and fire them a quick email both introducing myself and inquiring in regards to what tire pressures they’re running in their GT3-spec McLaren 650s. Physics don’t change when you cross state lines, nor do they change when you run races on different continents, so I’d like to know how a developer who made their access to real data a selling point, ended up being 7 PSI in the wrong direction. Is it a European thing to over-inflate your slicks? Was the team Kunos received data from experimenting with a drastically different setup approach? Or, in a situation that will upset the Assetto Corsa fanboys, is the real data advertised by Kunos just a marketing gimmick operating on a technicality or two?



125 thoughts on “Real Data?

  1. Although we only use Semi slicks at the MX5 Time Attack Cup in Cyprus (where it’s usually very hot most of the year) , 26psi for a slick seems pretty low! I would advise you to call up other teams as well because it sounds like a BS number to me or something I’d use for starting – cold – temperature..

    Liked by 2 people

  2. Zisus christ I will be happy when full version of Forza finally arrives on PC. Good bye simulation, welcome good looking car collection, career mode and tuning. Yes, tuning instead of pretend-realistic setup hunting. It will never be really realistic, wake up finally you goofy “hardcore” “simracers” for gods sake


    1. >we should stop asking for game elements because those get in the way of hardcore simulation elements
      >we should stop asking for hardcore simulation elements because GOD WAKE UP YOU GOOFY HARDCORE SIM RACERS IT WILL NEVER BE REALLY REALISTIC



      1. You should go out and drive, or play video games admitting they can’t be realistic. Both can be fun in their own way, but never in the same way. Game is a game. Simgame is a game. Real car is a real car. Stop fooling yourselves. Gamers know the difference, to hc simracers there seems to be a mystic element in simgames that somehow turns them … real?

        Liked by 1 person

        1. “You should go out and drive, or play video games admitting they can’t be realistic.”

          Your a fucking A class idiot, howd you think weve got where we are with psychics even in mainstream games ya goffy cunt, the fuck you even reading a sim blog you spastic cunt, ffs, you are exactly the problem, you wanna play “games” go play them, amazing how some cunts can spend hundreds of hours a week playing “casual” shit, and then try look down on ppl trying to apply some intelligence in their gaming.

          Get over the insecurity you feel when someone tells you the “game” you are playing was designed for insecure short attention span 12 year olds,and is actually so far from reality you might as well play mario carts, thats your issue, stop projecting, stick to your shit, where a pod filter adds fucking 30bhp, If you knew anything about cars or racing,that should annoy you, forza and GT is no good after so many hours unless of course you a dumb cunt,stick to gt planet and IGN

          Liked by 1 person

          1. Farking retard Hash..rf tires are also guesswork and has no proper real data that come with even shitty guesswork ugly looking tracks.


          2. Your favourite simulator is far from reality. The way it’s presented makes it a video game. Poor Hash, it’s hard to grow up, you are acting up like a three years old 😉

            Liked by 1 person

  3. id also prefer something from a blancpain team or such, unless you happen to know they use the same compound. i assume you reached out to multiples & this is just the first response?


  4. James let me tell you that you don’t need to run 33 “ideal hot pressure” for 100.00 tyre grip. You should just need ~80ºC for core temperature on these tyres.
    For example if you set 15 cold pressure in the setup you will get ~24 hot psi at ~80º tyre core temp and you get 100.00 tyre grip.
    So is BS the affirmation that you need 33 hot psi to get most grip from the tyres because temperatures are more important. But of course a too under inflated tyre gives you good grip from temperature but is easy to under perform in lap time or even overheat them which damages the tyre.
    So there are two difference you need to mind, the rubber has better grip at ~80ºC core but the physical form of the tyre will impact the car performance even if you get perfect grip from the rubber.

    That’s what I did, check my result.

    But this is just tyres, there are a lot more factors that influence how grippy or what performance the car gives you. Some of those factors are the track layout, environment conditions, setup.

    The conclusion is that you can indeed setup the car to have 26 hot psi and get optimal grip from the rubber when you reach 80ºc or so. Getting optimal grip isn’t exclusive to the 33º value you see in the files and is easily testable in game as you can see in my screenshot there. Optimal grip doesn’t depend on 33 but depends on hitting the right temperatures for the tyre. If you set high cold pressure (for example the default setup 25 psi) then will be harder to get optimal temps in certain tracks. So if that racing team seeks a ~26psi hot, then it means if they set higher cold pressure their car will suffer from not having tyre temperatures warm enough and giving them lower grip.

    Liked by 4 people

      1. Tyre pressure grows as the tyre gets hotter.

        But the thing is that you don’t need to achieve 33 hot pressure, because it all depends what you need from the car to do on a certain track.
        And higher the pressure less footprint the tyre has which it can give you less physical grip but usually more speed. And the reverse for lower pressure. But what matters is the result in performance and durability from all these combinations.


    1. Thanks for the extensive explanation, Aris 🙂

      Hopefully on his third article on the topic he will finally understand that he can also test his theories on track sometimes. Who spent time setting up those cars, knows pretty well that there is no magic number.

      James, people says that you’re a pretty decent driver. Prove it 🙂
      For sure you can write some pretty entertaining and lengthy articles based, the most of the times, on absolutely nothing.
      Nevertheless I’m looking forward to the next article everyday. It’s always fun to read what you will come up with. Somehow you manage always to surprise us. Well done. Your madness has no limit!


      1. Like in real life engineers don’t know the exact way to get a certain value out of the car or the tyres? What’s more difficult is how you get there on the track and if that really transforms in better lap times.

        There’s no magic number because no “magic number” wins you races or makes you better lap times. There’s only one ideal range that extracts the better out of the car or the tyres. And you need to be a good or great driver to make use of that.

        And apparently that racing team James contacted found their “magic number” of 26 hot psi for their tyres. Is the magic number for them… I hope you get that.


  5. Your team runs PWC and this series strictly uses Pirelli’s DHC compound tyre, which would be the “hard” compound in Assetto Cosra. They run these crazy low pressures in real life only TO GENERATE HEAT. Otherwise this compound never reaches optimum temperature.

    Guess what happens in AC when you try to run 33 psi on the hards : dead cold tyres.

    Guess what happens in AC when you run 7 psi less : HEAT !!!!! Whaaaaaatt ????!!!

    Maybe leave the technical stuff alone and stick to praising game value?

    Liked by 1 person

    1. Exactly what you said, and taking a more careful look at the tyres.ini you’d see for the GT3 there are these two lines.


      PRESSURE_IDEAL=33 ;Ideal pressure for grip

      Personally I don’t know the exact purpose of these parameters, but probably is just something to set the default setup or default data for the tyres.

      Because simple testing reveals that is all dynamic and depends in what state you want the tyres for the track or ambient conditions and with that get closer to the best temperature range.


      1. PRESSURE_STATIC is the value that the setup defaults to ex. when you click “reset to defaults” in the setup menu.

        As others have noted, you get more grip from keeping the tires in the optimal temperature range than you do from running the “ideal pressure”. Which is the same as any other sim I’ve spent significant time in. In GPL or N2003 there are optimal hot pressures that you aim for when creating a new setup but ultimately you use the tire temperatures as a guide. I don’t know what iRacing is like nowadays, but in the original tire model I used to build setups based entirely around hot pressures without even looking at the tire temps.


      1. Yeah… you didn’t get my argument at all..your team runs 26 psi not because it’s optimal for grip, but because it’s what’s needed to bring the temps into the proper range and the gain in grip is bigger in doing that than trying to run a 33 psi on ice blocks.


        1. 26 hot PSI isnt “crazy low pressure”, infact I ve always argued AC has always had “Crazy High pressure” being in the range of a fucking road tyre,its not so much temps,temps is just the info you use telling you about the contact patch, its about the contact patch, right temps will only go so far if your contact patch aint “optimized”, in other words you run as low as PSI as tyre allows for max contact patch, over heating and integrity of tyre is only thing holding you back, the temps are coming up with ideal pressure because of the contact patch being far bigger on lower PSI,when too low to much rubber on track (CTP) and is overheating, its simple, not sure what your point is or where it is heading.


          1. So what if AC has default 25 psi in setup? Is not like the setup is locked… make use of it. Understand that the default setup is for who races in AC casually, but besides that is probably the default state of the cars, even if no racing team uses the default state of the cars.
            Are you an advanced and experienced sim racer? Then instead of complaining about default values make use of your experience and change accordingly for you and the track.
            Is like those hardcore sim racers complaining the default surface in AC is optimum, you know you can change that, right? 🙂


        2. They are running 26 PSI hot because above all else, it works. That is their real life PRESSURE_IDEAL value.

          So for a simulator using real data, why the fuck has this number suddenly grown to 33 PSI?


          1. rf2 not even have a proper license gt3 car to begin with .rf2 is just a guesswork platform. Any manchild can hardcoded 26 psi in rf2 and maybe they get it right for gt3 hot tire but the rest just look at AM Mclaren mod, the car is fking horrible to drive and to look at, it twitchy, the onboard setting is fubar.It is awful.


          2. Tire pressure affects more than just grip.

            33 psi on a hard compound will have like zero give, zero side wall deflection and will chatter everywhere.

            In a stiff chassis professional race car that ride quality already sucks. Why make it worse?


            1. “33 psi on a hard compound will have like zero give, zero side wall deflection and will chatter everywhere.”

              Exactly, Im surprised in anoms big right up he totally ignores this very very important fact,also more rubber on ground with less pressure, means bigger contact patch.

              Ill post this again seems relevant….

              V8 supercars have had to put a limit on how low you can go setting it at 17psi, (im guessing cold pressure), as teams are running too low and having safety concerns of tyres, so has you wondering and James is absolutely spot on to question this, why does AC have such high “ideal” tyre pressures?


              1. because a lot of ppl seem to have zero clue what tyres are doing down there, imagine if that tyre was over inflated, like in ACs ideal range.


              2. Ideal tyre pressure for what circumstance? 33 is not ideal every time. If you have hard compound and you can’t put a good temperature into the tyres then aiming for 33 isn’t ideal. And you can change this in AC’s setup which will reflect on the track when driving. Ideal 33 maybe in a vacuum.. doesn’t say anything about the real needs because as you can easily test in game you can aim for a lower ideal hot pressure, for e.g 26, by lowering the cold pressure to ~17 and have better grip and performance than any ideal number you see in the files.


            2. Yeah dude instead of just running softer springs lets run a lower undamped spring rate in the tire with the added benefit of a less consistent contact patch.


              1. instead of just running softer springs lets run a lower undamped spring rate in the tire

                Oh ok, just over inflate tyres and run a softer spring? that totally makes sense, I guess thats why there has to be rules on min tyre pressure as all teams try and run as little as the tyre can handle and then some.


                1. It’s clearly not overinflated if it has the best contact patch, you fucking retard.

                  You don’t set the spring rate with the tires unless you have no time to change the springs.


                  1. The fuck you talking about ya twat,I was quoting the other spaz above,In AC “Ideal” pressure would be over inflated in real life,therefore not ideal pressure, cause less contact patch as well as many other issues, Ive even put a link to evidence race teams will run as low as pressure as possible, so much so it has to be regulated.

                    You fucking getting it yet you fucking spastic cunt?maybe if I draw a picture in crayons for you? you and the the majority of AC dick riders are the biggest collection of spastics IVe ever seen, you cunts would try to argue E=Mc2 is wrong if it meant Kunos could be wrong. fuck off back to you kunos cave,you fucking egg.


                    1. Oh and lets not forget, pressure seems to have very little effect on tyre temp spread in AC, again something thats lacking in AC,if you over inflate slicks you will get a mound in middle of tyre therefore over heat the middle of tyre in I/M/O.


          3. 25 static cold and 33 ideal hot can still be real data. But just like default setup values are real data it doesn’t mean is the best for competing in short or endurance races.

            What matters for real data is the whole range of possibilities and dynamics it creates for the car and the driver.

            For example Hard compound. Aiming for 33 hot psi on Nurburgring can keep you below 80ºC core tyre but still give you better lap time than aiming for 26 hot psi on the same track where you are comfortable above 80ºC core temp.
            So it depends, do you really need optimal tyre temperatures for the best lap times? Or can you sacrifice that and run higher pressure so that you’re faster despite having a bit less grip on the tyre rubber? Because we know that the physical form of the tyre that is influenced by tyre pressure will impact how the car behaves and how fast it can go.

            Also don’t forget that the current V7 tyres don’t have some attributes I don’t really understand about radial expansion and something about lat and long forces, but hopefully they’ll inform as usual changes to the tyre physics, especially since new parameters will also be available for mods.


          4. Wow. You really are clueless re: how and why a tire generates grip. It’s a *combination* of the structure of the tire (with pressure being the main variable here) and the compound it uses (hard, soft, etc). Suffice to say, when they talk about “hard” and “soft”, they’re referring to a single tire construction (which has its own sidewall stiffness, etc) but with varying compounds. And yes, there is an “optimum pressure” with regard to the way the tire itself is constructed that will give max grip, (AND HERE COMES THE KEY POINT YOU’RE MISSING) assuming all else is *equal*.
            But see, it’s not equal. Because, by far, the primary determinant of grip is tire temperature. Each compound is going to have an optimum temperature. And so tire pressure ends up being something you adjust primarily to attain a particular *tenperature* from the compound you’re running. This is why we check the inside, middle and outside temps. If you’re running underinflated, you’re going to get too-cold center temps with too-high inside and outside temps (allowing for variations cause by camber, sorry can’t teach you everything right here). If you’re overinflated, you get too-cool edges. Please just Google this shit for Gods sake.

            Anyway, yes – there *is* a max-grip pressure that is part and parcel of the tire’s *construction*, but it has relatively little impact when compared to tire pressures effect on the *real* determinant of grip, which is the temperature of the compound.

            TLDR: Both KS and anyone who’s ever been to a weekend at the track knows a lot more than you seem to understand about the variables that produce grip (and I’m just talking lateral grip right now) in a tire.


    2. I find it hard to believe Pirelli makes a conpound that is impossible to get proper temperature in, as that would be self defeating. In Silverstone in April maybe, Tooele in August not so much.


  6. Damn y’all are dense. Kunos doesn’t claim to replicate Michelin and Pirelli tires. Does GT3 run Soft Medium and Hard compounds? The tires in AC and other sims are always some kind of compromise – welcome to software development. Yes, “Real Data” is incredibly offensive and the case has been cracked – I think we should start a class action for false advertising maybe.


      1. I for one am just sharpening my pitchfork. This tire model nonsense pales in comparison to the treachery that will be unleashed with the console launch. Disgusting.


        1. You “triggered” buddy?you were less offended when you found me arse deep in ya mother,man you get really personally upset when ppl question AC.


            1. “But using “ya” is the epitome of elegant grammar?”

              Ha, good call, but its not about grammar, its about internet rules, I dont make em,(em, theres enougher one for “ya”) if you use “Y’all”, you are practically saying Im a inbred yank that breeds with vegetables and would struggle finding the US of mother fucking A on a world map,thats a genuine fact, you just cant call people idiots when you are claiming you all of the above.


  7. AC is fucking simcade you AC nerds. Kunos are also frauds that uses ripped content from Forza 4 for their DLC. Why can’t these lazy fuckers make their own cars if they are the gods of the sim racing genre?


    1. Because Forza cars are so good, excellent stuff for a video game. BTW, your favourite sim is a video game too, haven’t you noticed when playing it? You’re playing a video game, you pathetic nerd.


      1. I doubt Kunos can use cars ported from Forza without Turn 10’s consent, which means they are stealing car models from Forza, and selling it as their own and yet you will still shill for them, cunt. Instead of “Turn 10 buys Kunos”, it’s “Turn 10 sues Kunos”.


  8. “I’m aware there are a few third party setup applications that convey this info in a much more user friendly manner, but at it’s core, it’s equivalent to looking up the answers in the back of your math text book.”

    They have an app like this in AC now.


        1. Yet you give him visits and read what he has to say.

          I dont agree with everything thats writen here but its quite refreshing with someone that says what they actually think. On other boards you see people defending their favorite sim to all cost and their sim do it the best and so on, but when reading on prc you dont get that. Its more “truth” in these posts even though some of it are wrong.. if that makes any sense.


      1. James going back through many of your articles it seems to me like you might be the mentally ill one buddy, and a hell of a lot of people have called you out on it, you spend your days attacking and making fun of everybody else, but you whinge like a bitch if your comments section gets shitted on.
        You reap what you sew my friend.

        Liked by 1 person

          1. I actually don’t mind James and think he’s a pretty smart bloke for a Canadian, but fucked if I’m going to feel sorry for his comments section, he deserves every troll he gets in here and then some, don’t you James?


              1. It reflects the maturity of the 4chan sim racers. Because all these people that behave this way here try to be angels in the moderated forums.


  9. PRC readers curious to know how PRC could continue to pump out articles at such a rate soon realised that PRC were just regurgitating the same old rubbish over and over again.


  10. I would bet a testicle that the various spammers are the same guy. The LFS guy, the rF2 shill, the no simulation value guy, the major truth lunatic, the “stop impersonating Hex” guy… I bet it´s the same guy talking to himself.


  11. Just a thought, isn’t the ideal 33 hot a direct reference to the 25 psi cold? Because both parameters are in the GT3 tyres.ini
    So if 25psi is set, the tyres perform better at 33 hot psi. Which if you tested in game, the tyres don’t stay fixed on 33, they will fluctuate between 32 and 35 and will be different for each tyre as a consequence from the track layout.

    But that might just be the real data from factory. That’s why we have a setup which allows a range of pressures for the tyre. So for example if you need to set a lower cold pressure in the pits, then without doubt the tyre will expand at lower than 33, and that will be the ideal pressure for what you set in the setup.

    I guess the 33 ideal is only ideal if you set 25 cold. But this isn’t a guarantee this is the best strategy for the track and environment conditions.


  12. Did I not say there was drastic overinflation?

    I also recall saying that teams are running cold pressures that may be called ‘unsafe’.

    26 psi hot makes more sense for tyres of those dimensions than 33 psi but it also indicates a clearly ‘unsafe’ cold pressure.

    So the safe minimum is probably bullshit and ac tyres seem over-inflated as a general rule.


  13. How could a team run 26psi hot if Michelin and Pirelli say the wrath of god will fall upon you if you use anything less then 23-24psi cold in their slicks?


      1. Correct, I’m pretty confident that’s all it’s about. teams/drivers don’t care what pirelli or anyone else has to say when data clearly goes against their recommendations.


    1. Only some fantastic 3d models are made by modders. And good for them, making well detailed work and they can also showcase their stuff professionally.
      But then Kunos and Porsche work on the physics and sounds.

      Either way, out of the 23 or so Porsche cars coming to AC only a few come from the modding community. And they deserve it.. so why being so negative?


  14. Off topic, but it’s hilarious that Radu Oros is shilling hard for AC on Race Department, while everyone else is calling him out on his bullshit.


    1. Off topic, but it’s hilarious that Associat0r is shilling hard for rF2 on Race Department, while everyone else is calling him out on his bullshit.


  15. Stop this please, sim racing games are for driving and racing. They shouldn’t be used to personally attack other people, to doxx them, to discharge your everyday frustration in others. Please play the game you bought.


  16. Then tell the shills to stop their endless, mindless support of their favorite sim that constantly interrupts every forum with their endless dribble irregardless of the facts.


    1. Now people can’t present their opinions and ideas in favor of something that he gets called a shill and worse? Personal attacks and personal judgments don’t help anyone in a discussion. If you don’t have ideas to present in a public place, don’t come to an anonymous board and attack people on their backs.


  17. Yeah wish it that simple, I’ve seen the technique over and over, in forums that may be critical of a sim ,enter the shills with endless dialogue and misdirection until the topic is completely diluted and the topic just dies. This is a taught and effective tool. A shill isn’t name calling it’s a job title


  18. It’s the ideal pressure for grip, *if everything else was constant*.

    In the real world, and in actual AC sessions, these other things – tire temps, wear levels, etc. – are not constant, so the “ideal pressure for this session” changes dynamically by conditions.


  19. I shouldn’t be doing your homework, kid.

    McLaren 650S GT3-037 uses: F – PZERO 315/680 DH, R – PZERO 325/705 DH.

    Official PWC tire supplier as of 2015 is FRISBY PERFORMANCE TIRE.

    Now lets look at their catalog:

    – To better optimize performance never set cold pressures lower than 24 psi for the fronts and 26 psi in the rears. Hot pressure should never be lower than 30psi fronts and 32psi rears.
    – Maximum hot temperatures should be around 230ºF ~ 110°C
    – Optimum Working Temperature spread is about 50ºF ~ 10°C

    Now lets look at what PWC uses to measure ride height (that is, expected height for aero regulations):

    – Official tire pressures are 34 psi.

    And what Pirelli has to say to two other cups that use their P Zero slick series on P. Min:

    – Is the minimum value of the pressure that the tyre should run. NEVER use the tyre below the minimum pressure otherwise you will compromise the integrity of the tyre.
    – The pressure should be checked before the start of each run, INFLATE the tyre if the pressure is
    below the recommended value or change it.
    – Pressure below the recommended value will cause an excessive sidewall deflection, risk of air loss between bead and rim, risk of bead unseating. All this factors compromise the integrity of the tyre and can cause tyre breaking.
    – During the first lap out from pit and the warm up lap we strongly recommend to avoid curbs or any other kind of hard impact to prevent air losses.

    In the end, can GAINSCO/Bob Stallings Racing’s driver (by the way, you wrote gainEsco in your article link) be at 26 psi when hot?

    Sure. As is there’s no reason to doubt his statement.

    I don’t know their driving style, pit strategy and general tuning.
    If they see 20% under-inflation is helpful for their runs and the tire wear/damage is manageable, and they are allowed to run it (PWC has no rule on that issue), then they are free to do it.

    What you don’t seem to understand James is that I can run my car with 10 psi less.

    It won’t behave properly with the tire caving in and it will wobble, but it is drivable. It’ll just wear faster and probably cause tire failure with continuous use.

    So all those Pirelli recommendations are saying: “This is the standard range where our tire touches the ground evenly as it was designed for that 0° to 3° camber range. Surface heat spread should be 0-10°C across the surface at these standards.”

    If you feel that your general approach to corners due car behaviour, expected distance, track configuration and general use along camber/toe/aero/load profiles are heating them up unevenly, and deflating them helps you, then you do it.

    It is that simple.

    As a parting gift:


    1. “This is the standard range where our tire touches the ground evenly as it was designed for that 0° to 3° camber range. Surface heat spread should be 0-10°C across the surface at these standards.”

      HA not according to the AC community, ive pointed out many many times that the camber of GT3 cars in AC are absurdly large,and has issues with tyre temp spread, with many being close to 5 degress camber, the same as a bloody v8 supercar,a car famous for large cambers, also try your best to get a “ideal” spread of 10c, something AC fucktards argued with me for 3 days straight saying that 10c spread figure was rubbish(its all archived on this site and kunos), even if you put extreme camber, drive like a fucktard and all kinds of other weird shit you barely get close to 10c degrees difference,youll be lucky to get a 6 degrees spread, in other words, even with a stupid setup you still have perfect contact patch according to temps, and the reason 10 degrees is the accepted ideal,is because its too hard to get the spread any lower irl, but in AC no matter how hard you try you cant get ABOVE 10 degree spread, so glad you posted that info.

      Also one other thing….
      its a “recommendation”, there’s a reason race leagues have to set min tyre pressure despite tyre “recommendations”, cause teams will lower beyond whats recommended regularly for ever more grip, f1 not long ago was having this very issue, and ive posted a link with v8 supercar teams setting as low as -17psi cold, way below recomended PSI by dunlop,recommendations is to stop their very public branded tyres blowing out on tv, you may have 10 teams going .3 sec faster and being fine, but just one blowout/fail will be enough to send tyre manufactures into recommending higher then needed pressures, they dont want even one blowing in public eye.

      The long and short of it is this, AC is not a bad game, however if you are looking at setups and really into the engineering side of racing, you better be looking else where, as AC just has far to many little oddity’s in the setup side of things beyond just going of what feels best, I even had a prominent kunos forum member tell me to ignore all setup data and just go purely on “feel”,go figure.


      1. Have some laps in any AC GT3 and you will find that the cambers are OK, the temp spread is OK and the pressure gain/temperature relation is OK. Try it just to prove me wrong.


  20. soo, you don´t need to decrypt the data.acd to get the tyres.ini, they give them away for free you expert (\Steam\steamapps\common\assettocorsa\sdk\dev\v1.5_tyres_ac)


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