Tyre pressures

Discussion in 'General Discussion' started by Jeremy Talbot, Jul 10, 2018.

  1. Jeremy Talbot

    Jeremy Talbot Registered

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    With the new tyres that have come in with the Endurance pack etc do we now need to start adjusting them as part of our setup? Minimum pressure used to be the way to go, is that still the case?
     
  2. avenger82

    avenger82 Registered

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    Good question. I've read somewhere that lowest is not optimum for the new tires, but it's would be best to test (i.e. drive consistently with different pressures)
     
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  3. Rui Santos

    Rui Santos Registered

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    I see that outside temperature of the tires keep getting hotter than the inside, even with high camber values, i still don't understand this...
     
  4. datboi

    datboi Registered

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    Lowest is best. Like always

    My idea on this is that the load doesn't want to spread itself evenly across the tire but instead tries to find the most outside point when the car is turning. That's just a guess though. I think it makes sense when you think about centrifugal forces.
     
  5. patchedupdemon

    patchedupdemon Registered

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    Are you asking for qualifying or race race set up.
    I have found that lowest is fastest for qualifying but isn’t the best for races,as they tend to overheat
     
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  6. avenger82

    avenger82 Registered

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    So upgraded tire model didn't change that, it's a pity because it shouldn't be always like that IRL if I'm not mistaken.
     
  7. Rui Santos

    Rui Santos Registered

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    Nobody can explain why the outside part of the tire allways get hotter than the inside part when cornering (not even forcing)? It wasn't like this before, looks almost like the car has positive camber which is not correct! So i'd like some clarification on that...

    For example, last night, Formula Renault 3.5 2014, default setup, rubbered track and temperatures of the outside part of the tire that has more work is allways hotter on the outside, with a camber of -3.5 (default)...
     
  8. patchedupdemon

    patchedupdemon Registered

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    I’ve heard a lot of folks say that f1 and gt3 irl use the lowest allowed pressures ,but I’ve never bothered to see if it’s true
     
  9. Seven Smiles

    Seven Smiles Registered

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  10. Devin

    Devin Member

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    There have been documented cases of this since the 70s even. Essentially, if that wasn't the case, Manfred Winkelhock would still be alive today to name one documented case. During the race his pressures were so low that the tyre slipped away from the rim (so you can imagine how low it really was). In the following races minimum pressures were introduced.

    Generally speaking, low temperatures will inevitably give you more grip, however they will also cause more movement in the tyre leading to more heat buildup and eventual heat degradation, making low temperatures useless for long runs in many cases. If you follow F1, they introduced a thinner tread in recent races for a similar reason. And a few years back, like already mentioned, they greatly increased the minimum allowed pressures mid-season due to tyres constantly failing. Which shows that modern F1 still tries to use the lowest possible pressures.

    So for qualifying usually going to the bottom end of the limit makes sense. For long runs it depends on car, series and tyre.

    One exception to this is karting by the way. In karting we usually regulate pressures insanely low (down to 0.6 bar), but not too low because as stupid as it sounds, then the tyres would overgrip. That slows you down, causes bouncing and is generally unpleasant.
     
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  11. Bozoman500

    Bozoman500 Registered

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    I ran a weekend session at Toban 24hr in the Norma LMP3 just to focus on tire pressures with the new compound last weekend. Like many are saying the low pressure was great for running a warm up/hot lap/cool down stints. During practice I noticed the tire temps were out of control on the outsides with the middle struggling to gain and hold temps. In order to keep temps fairly even I first tried to add pressure and leave everything else on the chassis default. This did not help as much as I imagined it should. I was a bit befuddled until I noticed at higher pressure the temps moved to the inside edge of the tire and cooled down the outside just a bit. So I set the pressure back down and started changing front camber positively. After an hour or so I found a sweet spot with tire pressure and camber where I could hold temps in the front tires. The deg and temps were still slightly higher on the outsides but it was still an improvement. I am not at my rig to say exactly what the camber and pressure values were. I do know the camber was a good bit less negative than my general setups in most cars.

    While it lapped about 1.25 sec slower than qualifying it made for a great race setup. The tires lasted about 10% longer and while racing Ai at 110% skill and 27% aggression, I was able to race lap consistently within 0.75 sec of the LMP2s average race laps. I will try to post more details when I get back to my rig.
     
  12. ceecee

    ceecee Registered

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    British GP 2018 minimum tyre pressures
    24.0 psi/165.4 kpa(front), 22.0 psi/151.6 kpa (rear)
    FE EOS Camber limit : -2.75 ° / RE EOS Camber limit : -1.75 °
    https://www.fia.com/events/fia-formula-one-world-championship/season-2018/eventtiming-information-8
     
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  13. Jeremy Talbot

    Jeremy Talbot Registered

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    Race setup as yeah, they do overheat.

    Some good answers here thanks everyone.
    You changed both camber and tyre pressure to achieve that? So it looks like it something that can be played with, thanks!!
     
  14. Florian W.

    Florian W. Registered

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    Prepared a lot for the friday RD events, well tire pressure is totally wrong. We had this discussion way back when pcar2 got released. The default pressure was to low in that game, people found the "game changing" info by looking at the real world tire pressure of these cars.
    https://www.racedepartment.com/threads/game-changing-info.142309/

    Link to michelin https://www.gtplanet.net/forum/attachments/michelin-race-tire-cat08-pdf.679968/
    "MICHELIN® slicks are designed to operate at pressures ranging from 30 psi to 32 psi hot. A cold pressure of around 22 psi should be a good starting point, which can then be fine-tuned to your car’s setup and your driving style. You should never go below 19 psi cold, to avoid any risk of bead unseating."
    Well we never reach these numbers in rf2, with the default pressure we end up at 27-28psi (tested at road atlanta), 140kpa at around 26-27psi max (feels the best) ...
    Now i tried to reach 32psi, took me 3-4 laps to get the optimal pressure but its way worse (lower grip and sluggish tested at road america/atlanta)

    What is with these tire temps btw, we had 25°C track temps but everyone struggled with overheating tires. (RD event road atlanta)
    IRL temps reach 50°C or more and here we are having to slow down?
     
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  15. Stefan_L_01

    Stefan_L_01 Registered

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    I never understood why outer temps can be so high, especially when sliding. Tire deformation and suspension depends imo on how much lateral force the tire picks up. Logically there should be a defined maximum of tire deformation at a given load which gets lower in case you get into a drift as grip is less. But in rf2 I allways had the impression deformation and thus outer temp gets more and more beyond point of max grip.
     
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  16. Devin

    Devin Member

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    I am not sure if you're not aware of this, but track temperature currently has no influence on tyres in rFactor 2 for that exact reason, it would get too complicated for the average casual and it would break most mods because those weren't developed well enough to cope with temperature changes.

    Additionally, Michelin says cold pressure of around 131kPa the lower limit. This sounds about correct, since that also works well in rF2. rFactor 2's pressure gain at temperature gain is physically correct by the way, meaning that if you have significantly lower pressure at hot temps your temps are still either lower than those measured irl, or the real tyres were tested with actual regular air which expands quite a bit, which is part of why it isn't used in real racing.

    Note that rF2's "temperature" that the player sees isn't the actual gas temperature of the tyre. So comparing that isn't as simple as looking at ingame temps and pressures at any given time.

    Also, about driving, I have never managed to overheat the GTE pack tyres even though I am on the physical limit of the car. If everyone in that event has overheating tyres, I'd question everyone's driving big time. Judging by monday's rF2 community event, the majority of players unfortunately completely overdrive car and tyres and would struggle with the same issues in real life.

    Thing is, if you use 22psi cold pressure and try to bring that up to 32.5 psi, you reach an average of up to 95°C on that particular tyre which leads to massive thermal degradation, both ingame and in real life, so by the time you've reached that temperature you've kiilled your tyre. To add to that, if you heat it up as fast as in just four laps, that means your rubber significantly overheats because otherwise the gas temperature wouldn't go up quickly enough, ruining the rubber even further, practically removing all your grip.

    In real life they measure temperature using probe-type devices, which requires the driver to stop in the pitlane, spreading temperatures between internal gas and air surrounding the tyre, which means the tread will have cooled down significantly from how it is on track. So if you get 93°C even then, that means the internal gas is significantly hotter, or the surface was completely overheated shortly before measuring.

    Besides, your document is a decade old and even then I wouldn't necessarily say accurate anymore. Tyres don't usually run that hot if you want to keep them in shape, and they don't gain that much pressure either unless you use regular air. Source: I did my own testing on karts, on which obviously gas and temperatures behave the same, even though it's significantly harder to build up temperature in the first place. The low limit that you quote isn't actually necessarily accurate either, as many racing series have a limit that is significantly lower. Even in F1 they've raised it to 135kPa, previously it was much lower.

    Literally the only thing to take away from this is that rFactor 2 does not simulate tyre failures, so the low limit needs to be enforced by rules because otherwise you would get faster without actually breaking your tyres like you would do in real life.

    Also it is possible that thermal degradation might be a bit higher or lower than in real life, as some parts about tyres literally can't be simulated physically correctly and still have to be approximated, but considering the extensive testing the guys did I'm sure it's correct. Also, try actually finding documents about the exact tyre in question and you'll see that rF2 got it fairly right with the endurance pack. Oh, and don't compare this to pCARS. Ever. Their tyre model isn't actually physically accurate so I wouldn't expect it to be even remotely correct. It's a "game", or simcade at best. How else do you think did they get so many cars in that game? Obviously they can't be accurate. Hiring enough people to extensively test and build so many cars in such little time is impossible for even the wealthiest studio.
     
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  17. Andregee

    Andregee Registered

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    The Cars 2 tyre modell is far away from simcade. It works well with Features that no other sim offers.
     
  18. Ronnie

    Ronnie Registered

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    Like what? ;)
     
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  19. Andregee

    Andregee Registered

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    The brakes give the heat to the tyres so that you can control the heat up pressure with the brake duct size or you can heat up the tyres in the formation lap. Tyre heating and cooling depending of the track temperature works well so that you have to choose harder or softer compounds, all stuff whats been missing in Rf2. SMS put a lot effort into their tyre modell and to say its simcade is nonsense. Whats the Rfactor 2 modell than with such important features missing, Arcade? I prefer the feeling of the Rf 2 tyres but the missing of the features hurts me alot. Its simple boring to drive on a static track temperature into the night for example
     
    Last edited: Jul 14, 2018
  20. datboi

    datboi Registered

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    I agree mostly with what @Florian W. is saying. There's a set of fanboys here that think rf2 model is correct no matter what. I've read books and interviews by race engineers. Not once has any of them (not running a Pirelli tire) said 'we run the lowest pressure we can without the tire blowing up'. The vast majority are aiming for an optimal hot pressure.

    There's no optimal hot pressures for any tires in rf2. Just whatever the lowest you can run. To pretend it's not an issue is ridiculous.

    And it is very easy to overheat the rear tires on the gte mod. You haven't been driving on the limit if you didn't run into the problem. It is possible to solve the issue with good setup.
     
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