# Exagerated tire heating at high load

Discussion in 'Car Modding' started by Oskar, Sep 25, 2023.

1. ### OskarRegistered

Joined:
Jun 2, 2018
Messages:
24
0
I'm trying to figure out how to reduce or limit tire temperature at high loads.
At extreme downforce levels when pushing the car hard in corners, I see extreme (non-physical) tire temperatures frequently, like above 200, when the optimum grip temperature is somewhere around 80-90.
In reality the tire compound will boil off right at the surface before reaching these temperatures, taking heat with it, and effectively limiting maximum possible tire temperature.
Also at higher temperatures it seems like there's some tire cooling effect missing, or just some coefficient that would need to be tweaked.
Tire heating might be overestimated also, but I'm assuming that's a function of the tire simulation, so should be relatively accurate.
Are there any tire modding gurus that could help point me to the variables that I should be tweaking?

2. ### Robin PansarMember

Joined:
May 20, 2018
Messages:
139
107
To increase cooling of the surface temps you can change the values in this parameter.
ExternalGasHeatTransfer=(8,4,0.6) // (base, mult, power) - heat transfer coefficients to external air = base+(mult*(vel^power)), where vel is linear velocity of tire

I recommend increasing the third parameter as it'll affect cooling based on velocity. Many cars fail to have enough cooling on the straights.

To reduce heat generation from sliding you can increase the second value this line.
GroundConductance=(1000,0.003,0) // (base, mult, reserved) - thermal contact conductance coefficient to ground = base+(mult*pressure), where pressure is contact pressure and the reserved variable will be used at some later stage.

You can also play around with these lines, where the third value acts as a fraction of sliding power applied to the tyre as heat energy.
DryTerrainEffect=(0,1,0.5)
WetTerrainEffect=(0,1,0.167)
GrassTerrainEffect=(0,1,0.05)
DirtTerrainEffect=(0,1,0.07)
GravelTerrainEffect=(0,1,0.07)
RumbleTerrainEffect=(0,1,0.5)
SpecialTerrainEffect=(0,1,0.5)

The values given in this example are a decent starting point. Just keep in mind to have the same fraction value in DryTerrainEffect, RumbleTerrainEffect and SpecialTerrainEffect.

philrob, Emery and Oskar like this.
3. ### OskarRegistered

Joined:
Jun 2, 2018
Messages:
24
0
This is very interesting! Based off the tgm generator .ods file, I would seem like the default is to apply 100% of sliding power to the tire as heat.
That is just completely unphysical if the tire is being operated in a temperature and surface pressure range where it sheds compound material on the tarmac. But also, if the tire isn't leaving black lines, this should be a much more accurate assumption.
It would seem to need to be a temperature and surface pressure dependent "multiplier" to be more realistic under all conditions.

4. ### Robin PansarMember

Joined:
May 20, 2018
Messages:
139
107
Tyre temperatures are a really tricky thing to get right, and even know what is right. Real-life comparisons are very few unless you are one of the lucky ones to actually have access to some data. One decent reference that you have access to is some onboard thermal cameras of the tyres. There you can at least study the behavior of the contact patch and the heating/cooling of the surface.
Some good examples:
Rear end of a previous gen F1 car

Front end of a previous gen F1 car

Road car overlooking surface & internal temps, pressures

davehenrie and Oskar like this.
5. ### elgagonRegistered

Joined:
Dec 21, 2022
Messages:
197
127
When F1 showed the thermal cameras, some teams complained about it, because they didn't want to show the real tyre temperatures.
The FIA decided to show how the temperature changed, but the values were not real. There was an offset between the real values and the ones shown on TV (the real colours were different).
You can see it here.
It is strange that the tyre is hotter than the exhaust gasses.

6. ### LazzaRegistered

Joined:
Oct 5, 2010
Messages:
12,287
6,531
I don't remember if they had values shown at one point, but the colour sequence and temperature range can vary - so while an image will show distribution of relative temperature, you can't compare two images. (maybe they calibrate them consistently, maybe they don't)

Gas won't be picked up properly by the cameras they're using as that's not the goal - it'll certainly be much hotter than the tyres.

elgagon likes this.
7. ### elgagonRegistered

Joined:
Dec 21, 2022
Messages:
197
127
IIRC they never showed the values because the teams refused.

8. ### davehenrieRegistered

Joined:
Jul 6, 2016
Messages:
7,419
4,339
The tool shown on the road car at VIR would be very valuable for sims. @Coutie, can such a hud display be built for rF2?

9. ### CoutieModeratorStaff Member

Joined:
Oct 5, 2010
Messages:
3,768
2,236
Anything is possible, but it probably won't happen due to lack of time. There's already the real time tire display, can't remember exactly what it shows though, I think it does show temperature.

10. ### LazzaRegistered

Joined:
Oct 5, 2010
Messages:
12,287
6,531
Toggles between temperature and contact pressure, yep.