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Physics Tyres once again...

Discussion in 'Assetto Corsa Modding Discussions' started by Grabarz, Apr 17, 2017.

  1. Grabarz

    Grabarz

    Messages:
    64
    Ratings:
    +11
    Hello there i decided to refine my tyres model once again ..
    to create Z-tune i had to replace tyre set from 245/25R18 to 265/25R18 i didn't found anything which would be considered as street tyre that's why i've chosen to go higher and took 265/25R19 instead from Pagani Huayra front tyres ( mostly cause of tyre version [v10])

    at first i was happy with the result - car gained traction but tyre temps were off the limits after few corners - that's why i changed FRICTION_K but now I need to change the grip of the tyre and I do not know which parameter is important ....

    DAMP=600
    RATE=323960
    DY0=1.6426
    DY1=-0.044
    DX0=1.5866
    DX1=-0.044
    WEAR_CURVE=__cm_tyre_wearcurve_rear_4.lut
    SPEED_SENSITIVITY=0.003161
    RELAXATION_LENGTH=0.07471
    ROLLING_RESISTANCE_0=12
    ROLLING_RESISTANCE_1=0.00050
    ROLLING_RESISTANCE_SLIP=5245
    FLEX=0.000448
    CAMBER_GAIN=0.097
    DCAMBER_0=1.5
    DCAMBER_1=-13
    FRICTION_LIMIT_ANGLE=7.51
    XMU=0.22
    PRESSURE_STATIC=23
    PRESSURE_SPRING_GAIN=1980
    PRESSURE_FLEX_GAIN=0.4
    PRESSURE_RR_GAIN=0.55
    PRESSURE_D_GAIN=0.0005
    PRESSURE_IDEAL=32
    FZ0=3468
    LS_EXPY=0.7461
    LS_EXPX=0.8089
    DX_REF=1.51
    DY_REF=1.48
    FLEX_GAIN=0.041
    FALLOFF_LEVEL=0.88
    FALLOFF_SPEED=2
    CX_MULT=1.08
    RADIUS_ANGULAR_K=0.02
    BRAKE_DX_MOD=0

    [THERMAL_FRONT_4]
    SURFACE_TRANSFER=0.0180
    PATCH_TRANSFER=0.00027
    CORE_TRANSFER=0.0012606
    INTERNAL_CORE_TRANSFER=0.0034
    FRICTION_K=0.02581
    ROLLING_K=0.19
    PERFORMANCE_CURVE=__cm_tyre_perfcurve_front_4.lut
    GRAIN_GAMMA=1
    GRAIN_GAIN=0.5
    BLISTER_GAMMA=1
    BLISTER_GAIN=0.5
    COOL_FACTOR=1.85
    SURFACE_ROLLING_K=0.96492
     
  2. HypoToad

    HypoToad

    Messages:
    291
    Ratings:
    +50
    The spring rate or " RATE" of the tyre will affect the grip greatly as it allows the tyre to keep in contact with the road better on corners, lower it to increase grip by trial and error by percentage, try 10%, 15% & 20% less for starters. Don't know what it does to the wear of the tyres though, may be nothing or may be a lot, try it and see.
     
  3. mclarenf1papa

    mclarenf1papa

    Messages:
    1,004
    Ratings:
    +1,211
    That's not how AC works...changing the spring rate won't directly change grip in AC (there's no real contact patch simulation).

    @Grabarz you need to adjust DY_REF and DX_REF (lateral and longitudinal grip coefficients at reference load) to directly adjust grip. The V5 Tires thread on the official forum (in the physics modding section - sorry no link...on mobile) has the equations to calculate grip at a given load.
     
  4. HypoToad

    HypoToad

    Messages:
    291
    Ratings:
    +50
    Well for whatever reason lowering the "RATE" value greatly increases the grip of the tyres, to prove this I have a set of soft tyres with 3 different "RATE" values, I cut and pasted the soft tyre 3 times and simply changed the names, in the tyre.ini file, the stock value and 10% & 20% less, so soft normal, soft 10% and soft 20% with everything else the same, so in game I can swap between them knowing only the "RATE" value is different, even the wear and tcurves both point to the same files.

    Now I can lap faster, depending on which tyre I choose, normal is slowest, then 10% and 20% is fastest. The lap times don't lie IMO. So if you want better grip from custom tyres start by lowering the "RATE" value.
     
    Last edited: Jun 19, 2017
  5. Grabarz

    Grabarz

    Messages:
    64
    Ratings:
    +11
    thanks for advice but since i promised myself to be honest with reality i cannot do that. Reason is simple those tyres are 265/25R19 they cannot be "soft" enough they should be hard as rock, uncomfortable but grippy
    that's why i increased DY_REF and DX_REF both by 0.03 and it's fine for me now

    however I'm struggling with suspension now - and i have no clue how to make it stiffer ( less bodyroll ) ...