Roll resistance depending on tyre pressure

Discussion in 'Wish Lists' started by Raintyre, Feb 12, 2021.

  1. Raintyre

    Raintyre Registered

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    I wish Rfactor 2 tyres generate a realistic roll resistance amount, and that there is a realistic effect of low tyre pressure and toe settings on the calculation of roll resistance.

    If we have a realistic roll resistance building depending on tyre pressure we at least will have one side effect to prevent or atenuate the fact that sim racers always need to choose minimum tyre pressures available to improve lap times, and we would be closer to the creation of a sort of "optimum pressure range window".
    Despite the lack of a realistic pressure window for grip, perhaps roll resistance would help to discourage racers from choosing always minimum tyre pressure available, while currently there is not a single disadvantage for doing that. That doesn't correspond to real facts and actually generates a chain of physics flaws.

    Thank you.
     
    Last edited: Feb 17, 2021
  2. mantasisg

    mantasisg Registered

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    Hey, I have been doing mini research. Not a tire engineer, also don't really have all the time in the world to make a study on it, but it is interestign to do some small research from time to time...

    I have found one study that tested tire on with different pressures. And one interesting thing happened that with different pressures as speed increased the difference in rolling resistance was diminishing.

    This beign said they tested pressures that makes sense, pressures that are obviously enough to sustain tire stiffness and structural rigidity to hold up the load. Also I don't really remember what tire was tested, I should look up for that study again... I think it would be fair to make an assumption that the tire with no more pressure than atmospheric, rolling nearly on the rim might have it's rolling resistance increase multiple times.

    Anyway, it could be true that tire pressures aren't that big factor for top speeds. Anyway, still not absolutely sure about that, and of course thats with assumption that tire will remain its structural rigidity and not fail due to fatigue and heat.

    One thing that is certain is that rolling resistance should be major factor at accelerations from low speeds, not even talking about sustaining high lateral loads if they would be flexing like a piece of cloth and totally ruining pressure distribution at contact patch.

    Anyway, it becomes more clear that tires in rF2 are too rigid themselves, and don't need pressure to aid rigidity. I'd be happy to get a proof that would show this assumtion being wrong. I have no idea if that is some rF2 limitation, or all tires in rF2 are built with much too much stiffness.

    Judging by my other little research about runflat tires, they are rather unpleasant to drive, also they are heavy. So I don't see it being logical if racing cars would run tires that are reinforced, thus heavy as hell.

    Anyway there are many different tires IRl, and undoubtedly they are all different.

    In rF2 I'd like to see this with tire that has 0kpa relative pressure in it.
    [​IMG]
     
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  3. Raintyre

    Raintyre Registered

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    Yes, that seems natural. As speed increases, tyre temperature increases, and with higher temperature roll resistance decreases (due to double effect: improved rubber hysteresis at contact patch zone and also reduced contact patch area itself).
    The tyres with less initial pressure produce more heat (due to bigger contact patch), then they reduce more roll resistance than the tyres with more initial pressure, which will not produce so much heat.
    However, only the difference in resistance is reduced. That doesn't mean the tyres with less initial pressure will end producing less roll resistance than the others.

    That's just another proof of the high sensitivity of tyres for roll resistance depending on pressure.

    Roll resistance depending on temperature, load, speed, pressure... (oldie but goodie):
    https://deepblue.lib.umich.edu/handle/2027.42/4274
     
  4. Lazza

    Lazza Registered

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    rF1 just based rolling resistance on tyre deflection, which was itself dependent on load, rotation speed... pressure? I can't remember. Not perhaps the most accurate way to do it, but is it more than we have in rF2?
     
  5. Sim_Player

    Sim_Player Registered

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    bit off topic, has anyone tested on how pressure affects temperature and wear of tyre ?
    if this is done correctly then it will also add realistic tyre pressure setup.
     
  6. Raintyre

    Raintyre Registered

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  7. Sim_Player

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