Cars – Tyre Physics - ac-custom-shaders-patch/acc-extension-config GitHub Wiki
Extended Raytracing for Tire Collision Detection and Contact Patch Movement
Enable in tyres.ini:
[_EXTENSION]
LATERAL_RAYS=0 ;per side, 0 means 1 in middle
LONGITUDINAL_RAYS=4 ;per side, 0 means 1 in middle
MAX_RAY_ANGLE=60 ;degrees swept per side
DISABLE_RAY_DOUBLING=0 ;set to 1 to disable low speed ray doubling (good for performance)
Load Sensitivity Smoothing
[_EXTENSION]
SMOOTH_LOAD_SENS = 1 ;setting to 0 gets rid of cubic interpolation on load sensitivity luts, which can help avoid issues with certain lut shapes.
Deterministic Sidewall Deflection
Adds vertical (pre 0.3.0) deflection from lateral and longitudinal contact patch deflections (post 0.3.0). Note that solution is deterministic (deflection directly derived from forces), as proper simulation cannot be done at AC's 333Hz.
Example (tyres.ini)
[FRONT]
SIDEWALL_K_MULT=1.0 ; multiplier of vertical rate for lateral stiffness
SIDEWALL_K_MULT_X=2.0 ; multiplier of vertical rate for longitudinal stiffness
Thermal Model Extension
Revamps AC’s tire thermal model by adding carcass temperatures and improved heat-transfer modeling.
Parameters become more realistic but more difficult to tune.
Example Implementation (tyres.ini)
Only extension-relevant parameters shown. All Kunos parameters are still required.
[THERMAL_MODEL]
VERSION = 1 ; version of thermal model. Current versions: 1, 2. V2 works with extended rays to dynamically calculate side to side temperature distribution, plus changes some calculations.
[THERMAL_FRONT] ; Kunos parameters (some repurposed)
SURFACE_TRANSFER=0.93 ; cooling rate from track to tire surface
PATCH_TRANSFER=0.002 ; lateral heat distribution on the tread
CORE_TRANSFER=0 ; obsolete
INTERNAL_CORE_TRANSFER=0 ; obsolete
FRICTION_K=0.0127 ; friction-generated heat
ROLLING_K=0 ; obsolete
PERFORMANCE_CURVE=tcurve_1.lut ; celsius | grip_multiplier
COOL_FACTOR=8 ; speed²-scaled multiplier for SURFACE_TO_AMBIENT
SURFACE_ROLLING_K=0.001 ; heat from internal tread resistance
[THERMAL2_FRONT] ; new CSP parameters
CARCASS_ROLLING_K=0.15 ; rolling resistance → carcass heat
BRAKE_TO_CORE=0.0006 ; brake heat → internal air
SURFACE_TO_AMBIENT=0.076 ; surface → air
SURFACE_TO_CARCASS=0.023 ; surface → carcass
CARCASS_TO_SURFACE=0.61 ; carcass → surface
CARCASS_TO_CORE=0.025 ; carcass → internal air
CORE_TO_CARCASS=0.0005 ; core → carcass
CORE_TO_AMBIENT=0.002 ; core → ambient (via rim)
Temperature-Dependent Slip Dropoff Curves
Lookup tables for falloff vs. temperature.
⚠ Note: Does not display correctly in the Tire Tester App.
Example (tyres.ini)
[FRONT] ; or any compound
FALLOFF_LEVEL=0.7
FALLOFF_LEVEL_CURVE=tyres_fall_level.lut ; temp | falloff_level
FALLOFF_SPEED=1.5
FALLOFF_SPEED_CURVE=tyres_fall_speed.lut ; temp | falloff_speed
Practical Temperature Ratio
Controls weighting between surface and carcass/core temperature when calculating grip.
Example (tyres.ini)
[_EXTENSION]
PRACTICAL_TEMP_RATIO = 0.25 ; 0 = core/carcass only, 1 = surface only (AC default = 0.25)
Spring Rate Change With Camber
Applies a multiplier based on a lookup table.
Example (tyres.ini)
[FRONT]
CAMBER_SPRING_MULT = camber_sr.lut ; degrees | spring_rate_multiplier
Rolling Radius Change With Load
Kunos treats rolling radius as constant; this corrects that behavior.
Example (tyres.ini)
[FRONT]
ROLLING_RADIUS_MULT=0.1 ; proportion of deflection applied to rolling radius (0–1)
Quadratic Radial Growth With Wheel Speed
Adds a quadratic term for tire growth at high angular velocity.
Example (tyres.ini)
[FRONT]
RADIUS_ANGULAR_K_2=0.05
; radius_add = (K2/1e6)*ω² + (RADIUS_ANGULAR_K/1000)*ω
Longitudinal Grip Adjustment With Camber
Quadratic camber → DX scaling.
Example (tyres.ini)
[FRONT]
DX_CAMBER_REF=3 ; reference camber angle (deg) — must not be 0
DX_CAMBER_MULT=0.98 ; multiplier at reference angle
Additional Slip Parameters
Used for shaping slip-dropoff behavior.
Example (tyres.ini)
[FRONT]
DROPOFF_FACTOR_0=60 ; visualize at https://www.desmos.com/calculator/dtlzovroom
DROPOFF_FACTOR_1=1