The online racing simulator
Technical queries on tires
(81 posts, started )
Technical queries on tires
Greetings all, i have a few doubts pertaining tires and i've listed the questions below.
I appreciate to aquire all relevant help and advices which i will be applying to both simracing and real racing.

1. What does a peak temp of a tire represents? Is it the highest temp a tire can get or is it the point the tire has the most traction? Is it related to overheating point?

2. As a tire wear down, it starts to releases some of the heat and start to go down in temperature. In what way does this cool off effect have an impact on performance?

3. A tire with a higher pressure has better handling but sacrifices traction. Handling here refers to how quickly it reacts to driver's input. Am i right to say that?

4. Besides pressure & temperature, do tire profile(sidewall) contributes to the car's cornering performance and how are they affected?
#2 - Jakg
1 - Peak Temp - Temperature at which the grip is optimum.
Use the F9 display ingame to see the tyre stats.

Colour codes are as follows...

Blue - Cold
Green - Optimum
Orange - Starting to overheat
Red - Cooked!
#4 - amp88
Quote from atenza63 :
2. As a tire wear down, it starts to releases some of the heat and start to go down in temperature. In what way does this cool off effect have an impact on performance?

The impact on the performance will really depend on how low the temperature of the tyre falls as it wears. How low it falls depends on your car setup and driving style. You only need to really consider tyre wear if you're in quite a long race. depending on the track length, car type, driving style etc it can take anywhere from 10-20 or so laps for the tyre tread to start wearing significantly. What I try to do when I modify a setup for a long distance race is to have the tyres at their optimal performance (i.e. optimum temperature) at about 75% of the race distance. If you try to get the optimum performance sooner (say 25-50% race distance) then when you get to towards the end of the race you'll probably find your tyres have cooled too much and you'll be very slow. If you try to get optimum performance at the end of the race then you're wasting the best bit of the tyres. Something else to consider is that when you create a setup that's going to give you optimum temperatures at 75% distance your tyres will be above that temperature (and liable to overheat) for the start of the race. You will need to keep this in mind so you can alter your driving style to keep the tyres within a reasonable temperature range. There are a few things you can do to alter your driving style to try to keep the tyres in range:
  • Brake slightly earlier than the limit (this will reduce the chances of brake lockups which can create hotspots on the tyres)
  • Apply the throttle smoothly (reduce wheelspin and power oversteer)
  • Carry slightly less speed through the apex of corners than possible (decreasing stress)
As the tyre tread wears down you'll be able to push harder while keeping tyres within a reasonable range. This is because with less tread depth there's less rubber to move around on the surface of the tyre which creates less temperature.

Something to bear in mind with the above is that it can be much easier in theory than in practice. When you're battling for position you can forget optimum temperature ranges and conservative driving.

Quote from atenza63 :3. A tire with a higher pressure has better handling but sacrifices traction. Handling here refers to how quickly it reacts to driver's input. Am i right to say that?

Up to a point, yes. Higher tyre pressure normally gives better precision.

Quote from atenza63 :4. Besides pressure & temperature, do tire profile(sidewall) contributes to the car's cornering performance and how are they affected?

Yes. Sidewall strength (and thus how much it flexes) has an impact on tyre performance. If you take a look at this video you can see how much the tyre sidewall crushes under braking and deforms through right hand corners. The amount of deformation in the sidewall will effect the contact patch of the tyre. The more contact patch the more grip, obviously. A softer sidewall will deform more so give more grip, but may feel less precise to the driver (same thing as the tyre pressure). A stiffer sidewall will give less grip but more precise feeling.
what amp said, but just to elaborate on 3.

the higher the pressure that more responsive the handling of the car, as there is less rubber in contact with road, therefore less resistance to turning and also less tyre flex. low pressure will make the tyre respond slowly, but will increase the contact patch and therefore grip.

another thing to consider is how the pressure affects the tyre temperature, general rule high pressure = less heat
#6 - Riel
I never really feel the difference between a green inside of tire and just the green contact patch.

Can anyone shine a light on that?
something to do with camber angles or something, im not very technical lol.
#8 - amp88
Quote from Riel :I never really feel the difference between a green inside of tire and just the green contact patch.

Can anyone shine a light on that?

I don't understand the question. Can you provide more details please? Include screenshots of the F9 display if possible.

Quote from danthebangerboy :something to do with camber angles or something, im not very technical lol.

What was the point of this post?
The point was, presuming i understood what he was saying correctly, is that you will end up with the inside edge of the tyre green before the rest of it if the camber is set too much, Shit, thats not what he means is it, i think he might mean the difference between the actual air temp inside the tyre and the temp of the contact patch. Whoops.

So if i have got the meaning of the question right this time :hide: Then if the inside of the tyre and the contact patch are both green, then your tyres are nicely up to a good racing temperature, but if the inside of the tyre is blue and the contact patch is blue, then the whole tyre is still cold, and if middle is blue and the contact patch is green or orange or red, then the heat is only on the surface of the tyre and not the whole thing, indicating scrubbing tyres or excessive wheelspin.

If the whole tyre is green but one side or one spot of the contact patch is orange or red and the rest of the contact patch is green, then its either a flat spot due to locking the wheels under braking, or too much camber or toe in/out, depending on which side is hotter.

There is a guide somewhere on here that explains it all better than i can, and as soon as i find it again i will post a link in here.

EDIT: this isn't the guide, but tyre physics are discussed fairly in depth in this thread... http://www.lfsforum.net/showthread.php?t=57041
Quote from atenza63 :Greetings all, i have a few doubts pertaining tires and i've listed the questions below.
I appreciate to aquire all relevant help and advices which i will be applying to both simracing and real racing.

1. What does a peak temp of a tire represents? Is it the highest temp a tire can get or is it the point the tire has the most traction? Is it related to overheating point? the temp at mamimum grip, not related to overheating point

2. As a tire wear down, it starts to releases some of the heat and start to go down in temperature. In what way does this cool off effect have an impact on performance? the closer to optimum temperature the better overall, nomatter what the amount of tread TO A POINT

3. A tire with a higher pressure has better handling but sacrifices traction. Handling here refers to how quickly it reacts to driver's input. Am i right to say that? a tire with less pressure has less reaction time but more of a footprint, so more grip. but a higher pressure heats up less, with less grip but a more immediate affect

4. Besides pressure & temperature, do tire profile(sidewall) contributes to the car's cornering performance and how are they affected? if you go overe a bump, the more side-wall or profile the tire has, the more of the bump the tires take compared to the suspension and compared to the passengers

hope i answered all of them correctly
Quote from amp88 : What was the point of this post?

As I read it, he's asking the difference between having the inside of the tyre heated up and having green on the contact patch.

While it's quite easy to bring the contact patch to optimal temperature, the inside of the tyre (which I suppose represent the temperature of the air, color coded wrt the optimal temp of the compound) can be harder to warm up. E.g. in the LX4/LX6.

His problem is he can't feel any change in the handling.
#12 - Riel
That indeed was my question: the inside of tires compared to the green outside.


So, when I want to conclude that:

1: Both Blue:
Tires still cold

2: Outside green, inside blue:
I am not driving smooth. The outside heats up due to wheelspin and scrub, and not by general rubber deformation. Less pressure to gain deformation and better driving lines are important.

3: Both green:
Perfect. GOod combination of tirepressure and driving style.

4: Inside green outside blue:
Won't happen but well looks like driving like grandpa on soft pressure


My REAL question now was:
How do I feel the difference between situation 2 and 3? I mostly don't mind a blue inside, as long as my outside stays green ... But, is this the right way of thinking ?
There are some cars where you can end up with a blue outer band while the inside is green, surely restricted ones where the tyre is supposed to withstand much more power and speed, as the Baby-R which I was practicing with yesterday but I think there could be more.

My guess is the inside of the tyre provides heat inertia to the tyre, e.g. it slows down contact patch heating in the warm up phase and then slows down its cooling in later stages. The same could be said of the rim too (if you look closely on some cars that warms up too) though I suppose to a limited degree.

The XFG is a great car to do some testing about this, it's easy to bring the patch up to temperature and then the inside will come up as well.

NB: in LFS there's no such thing as 'cold' tyres out of the pits. They're already above ambient temperature, and an easy way to check this is to let the car sit parked along the track for some time, the tyres will cool down to about 20 °C IIRC.

This has been the source of some arguing since tyre blankets may only regarded as realistic for the faster race cars.
Quote from Riel :That indeed was my question: the inside of tires compared to the green outside.


So, when I want to conclude that:

1: Both Blue:
Tires still cold

2: Outside green, inside blue:
I am not driving smooth. The outside heats up due to wheelspin and scrub, and not by general rubber deformation. Less pressure to gain deformation and better driving lines are important.

3: Both green:
Perfect. GOod combination of tirepressure and driving style.

4: Inside green outside blue:
Won't happen but well looks like driving like grandpa on soft pressure


My REAL question now was:
How do I feel the difference between situation 2 and 3? I mostly don't mind a blue inside, as long as my outside stays green ... But, is this the right way of thinking ?

The question is wrong as you got the base of your question wrong: the air temperature inside the tyres is probably the most irrelevant on the whole F9-display... It only affects tyre pressure (as you know pressure increases with heat in a closed environment)... In fact if the air inside stays cool, it will cool the tread from the inside...

And as the only way the air temperature rises in LfS is by heat from the tread transferred to the inside your situation 4 will never arise...

@NightShift: That's the sidewall, not the rim...
Quote from Riel :I never really feel the difference between a green inside of tire and just the green contact patch.

Can anyone shine a light on that?

tire warms up at the contact point, right? so it differs where is your contact patch in given setup.
Quote from bbman :The question is wrong as you got the base of your question wrong: the air temperature inside the tyres is probably the most irrelevant on the whole F9-display... It only affects tyre pressure (as you know pressure increases with heat in a closed environment)... In fact if the air inside stays cool, it will cool the tread from the inside...

I was always wondering how LFS simulates cooling from the outside becasue I always had the feeleing that tires once hot cant be cooled down driving competetive - I would have to go 5s a lap slower to get them cooled down for3 laps at least. So I have a feeling that cooling down with speed should work better.
Quote from AndRand :I was always wondering how LFS simulates cooling from the outside becasue I always had the feeleing that tires once hot cant be cooled down driving competetive - I would have to go 5s a lap slower to get them cooled down for3 laps at least. So I have a feeling that cooling down with speed should work better.

There is a cooling from the outside as well, you can see this very well if you set the wind to orcan-like, but I agree the temperature model is grossly flawed - there should be much more fluctuation than there is currently, not just faster cooling...
The tread on race tyres is typically a third of the thickness of a road tyre. If LFS does not adjust for this, then race tyres will store too much heat energy and thus heat and cool too slowly.
Quote from bbman : @NightShift: That's the sidewall, not the rim...

I know where the sidewall is

Take a look at the attached screenshot, you'll notice there's an additional part under the sidewall, the temperature is different as well (this you'll see well by taking a look at each wheel) - if that part is not the rim then I don't have a clue about what it is, the shape looks correct to me.
Attached images
lfs_00000141.jpg
Quote from NightShift :I know where the sidewall is

Take a look at the attached screenshot, you'll notice there's an additional part under the sidewall, the temperature is different as well (this you'll see well by taking a look at each wheel) - if that part is not the rim then I don't have a clue about what it is, the shape looks correct to me.

the bead
It is in fact the rim and LFS also models its heating.
#21 - Riel
Quote from bbman :It only affects tyre pressure (as you know pressure increases with heat in a closed environment)... In fact if the air inside stays cool, it will cool the tread from the inside...

And as the only way the air temperature rises in LfS is by heat from the tread transferred to the inside your situation 4 will never arise...


Ah.
So my setupped-tirepressure is pressure @ cold tires, and the CURRENT pressure is the pressure next to it ...
The setup pressure is pressure at optimum air temp, not cold temp AFAIK.
That's really stupid, how the hell do you set up pressure at optimal temperature like that.. IMO not realistic if that's true
Maybe so, but isn't it easier? As we don't have to worry about how pressure changes with temperature as much.
Hogwash. Should come out of the pits with ambient temp tires and have to worry about your pressures properly.

No more EZmode.

Technical queries on tires
(81 posts, started )
FGED GREDG RDFGDR GSFDG