Taken from LFS Manual

Tyre temperature & wear


Tyre temperature & wear


[F9] The F9 display shows four small windows each containing a 2D profile of a tyre, some numbers and three grey bars.
There are six areas in the diagram - three contact patches, the sidewalls and the air temperature. Each area goes from dark blue (cold) through green (ideal) and into red (overheated). There is also black, but that is only shown inside the tire after a blowout or puncture. Above the tyre diagram, there is a set of three numbers, which give the exact temperature of that tyre part. However, these numbers only represent the average temperature of the whole contact patch (from the inside up to the surface) - if you press and hold Ctrl+Shift, you can see the the actual surface temperature, which rises and falls much more quickly during a race. Bear in mind that since the tyre diagram only shows the top section of the corresponding tyre, a 'flat spot' on a spinning wheel is represented by little flashes of red.
At the top of each window there is a set of moving grey bars showing the footprint pressure of the tyre on the road. The display gives a good idea of how much camber (lean) the wheels have at any given point in time. With most cars there is a change in camber when the body rolls in a corner, but in order to find the most grip the wheel needs to be upright (relative to the road surface), when the bars are level the wheel is vertical to the road.
Last but not least we have a little brown bar that appears inside the tyre diagram, this brown bar refers to the amount of dirt on the tyres. Dirt reduces grip by a huge amount and therefore you should be more careful after a even a tiny 'off' - it can take a few corners to clean your tyres up again.

http://en.lfsmanual.net/wiki/Display

but yeah the tyres are a little gripless at high temp, but i've never gotten tyres to 170c, so i couldn't tell you what they are like

Quote from Matrixi :

Thanks mate, that did the trick. 6 years in and still learning new things!

Still doesn't explain the very hot tire grip levels though.

Wasn't going to mention the 2003 registration and not knowing thing

When tyres get too hot the surface rubber melts this is evident when a driver flat spots a tyre i.e. less grip - longer baking distance and rapid localised wear -flatspot. It also shows up in other forms such as blisters which are detrimental to tyre usefulness and life.

I think that the surface temps in LFS do approximate what I'd expect to happen in real life but I don't think the core temps are a good approximation of real life tyres.

The heat model seems to be centered around frictional heat, while this is accurate for suface temps I don't believe its a good model for the core temp of the tyre carcuss.
Rubber is actually a good insulator and hence the surface temp and core temp can be very different for extended lengths of time throughout a race. The core temp should be predominately influenced by the stresses passed through the tyre rather than the surface temp of the tyre radiating inwards.

For these reasons I suspect LFS tyres tend to heat too quickly and also often heat in an unbalanced way i.e. driven wheels can maintain temp well while the non driven wheels often remaining less than optimum. This is also why you often hear that the fastest way to drive in LFS is to slide the car around more than you would in real life and why you see hybrids on the rear of the GTi etc, etc. Because the core temps are so closely linked to the surface temps the surface temps I believe tend to esculate at a much faster rate than what would happen in real life.

On a side note - tyres will tend to give there best performance early in there life cycle, this is because the chemical make-up of a tyre is continually undergoing change thoughout its life cycle. In the coverage of the latest round of V8Supercars at Winton they threw up a few interesting graphs of tyre performance of a 20 lap stint. The standard control tyre would see it's fastest lap time in the first few laps and have dropped off by 1-2 sec a lap after 20 laps, while a soft sprint tyre was much faster upto 2 sec a lap faster over the control tyre its degradation was much more severe. At the end of 20 laps the sprint tyre would be 2 or more sec slower per lap than the control tyre.

Don't forget road tyres are a completely differnet kettle of fish there too, read - Steel Belted Radials
i don't think LFS simulates the way metal holds heat does it? (i'm asking, this is not a statement of fact etc etc)

EDIT - IIRC Race tyres don't have steel belts...but i could be wrong on this..

Quote from Glenn67 :

<Last post>

Well spoken, this is what I would have said if I could have put it in to words.

Thanks Rusty, much better than anything I could do now - Rioja does not help.
Sorry Matrixi for the approximate information (ctrl+shift), I was not able to test at this time of the day.
One question remains: Where is the temperature for F9 display taken?
That may explain behaviour, although I agree that it seems to reach too high temperatures and cool down very slowly.

Quote from kamkorPL :

xrg shouldn't be even able to reach so high temps, because the thread would go off, speaking from experience here

which hints to lfs having an incomplete tyre heat model not nescessarily a wrong one

also i agree with glenn that the tyre core temperature model seems to be a bit off but this has unsurprisingly been discussed on this forum before
it has always struck me as fairly wrong how the rubber seems to be a fairly good insulator when it comes to colling the core but at the same time a very good heat conductor when it comes to heating it

fortunately unlike the grip vs temperature question this one is something that can easily be resolved rigorously at home with an old tyre a thermometer and a lighter
anyone bored enough to do the measurments?

Don't forget to open the window during testing

Like I said, the heat vs grip level seems to be somewhat correct, overheat a tyre and it performs like driving on ice. I have overheated tyres before in real life and that is how they act.

How the tyres get to overheated is the problem, And I'm glad people have finaly started to come around to that conclusion.

The temps of a tyre in LFS seem to be completely derived from friction, exept maybe for the sidewalls. where as in reality, most of the heat comes from within the tyre itself, as the rubber bends and flexes it generates heat, so unless you do a burnout, the surface temps should be somewhat lower than core temps. Its like bending a metal rod, if you have ever done it you will notice that the rod heats up where it is being bent. This is due to friction between the molecules of the material.

Tyres heat up mostly on a molecular level, friction heats the surface, but flexing and bending heats the core and sidewalls alot more.

This is why you will often see transport truck tyres blow out on the highway if they are slightly underinflated. Most people think it is due to friction, where in reality it is due to the tyre flexing to much because of the load.

This is another thing that is different in LFS than real life, the tyre pressures have an effect on tyre heating, but I don't think it is completely for the right reason. This puzzled me at one point, I had the sidewalls overheating on the XRR, I thaught I could fix it by increasing tyre pressure, but it didn't work. Now I belive I know why.

It sure isn't an easy topic and data is sparse on this subject! I did recently found this PDF which has measured and simulated tire temperature during the course of a lap. I assume those are outer surface temperatures but I'm not sure.

http://www.ipg.de/fileadmin/do ... RaceCM_racetec_200611.pdf

pages 13 and 16 have some info..

I do think LFS isn't quite right here, but if that means the model is wrong or the parameters going into it are wrong, hard to say!

Very nice video there.I don't see how some people say there's almost nothing to fix.Drifting a whole corner with the clutch in?Drifting in 4th gear @ 2500 RPM...in real life?Yeah right....

Damn. I just typed out a whole post and went to press backspace and my browser went back to the last page *Tear*

Basically.. yeah nevermind..

Oh and I know two people in this thread I will never take advice from..

Just close this, you all feed off of drama. e experts fuel the drama to expell a thread until everyone contridicts each other.

I was expecting a total noob video, but it does highlight an extremely important issue with the game people who aren't "in the know" would be aware of.

A bit like the video of people trying to doughnut in Gran Turismo.

Good job, however, it'd be vital for us to see the same conditions in a road car.

Quote from AjRose :

Damn. I just typed out a whole post and went to press backspace and my browser went back to the last page *Tear*

use Opera, it doesn`t reload the page from scratch. you could have just clicked on the forward arrow again and found yourself on the same page with your text still there.

Quote from theirishnoob :

i cant last more then 30 seconds... curse you ps3 controller/T1/windows 98

STAY on track for 30 min's. Stop your engine and don't move.

Quote from Hallen :

OK, good to know. I just assumed that nobody would be stupid enough to go out and burn up perfectly good, new, race tires for drifting. What a waste. A good set of used up R888's maybe, but it would seemingly be better to just grab any old discount tire that's harder than a rock. But, obviously I know nothing about the fine display that drifting is.

good old elitist racers :rolleyes: grip is everything for drifting, why not get a good new tyre that will last longer and get more grip then some old cheapo tyre

Quote from Matrixi :

The core temp should be predominately influenced by the stresses passed through the tyre rather than the surface temp of the tyre radiating inwards.

For these reasons I suspect LFS tyres tend to heat too quickly and also often heat in an unbalanced way i.e. driven wheels can maintain temp well while the non driven wheels often remaining less than optimum. This is also why you often hear that the fastest way to drive in LFS is to slide the car around more than you would in real life

Quote from Shotglass :

it has always struck me as fairly wrong how the rubber seems to be a fairly good insulator when it comes to colling the core but at the same time a very good heat conductor when it comes to heating it

*exactly*! It can't work so well both ways, this simply observable fact is a great place to start looking at this issue.

Quote from DragonCommando :

The temps of a tyre in LFS seem to be completely derived from friction, exept maybe for the sidewalls. where as in reality, most of the heat comes from within the tyre itself, as the rubber bends and flexes it generates heat, so unless you do a burnout, the surface temps should be somewhat lower than core temps. Its like bending a metal rod, if you have ever done it you will notice that the rod heats up where it is being bent. This is due to friction between the molecules of the material.

I haven't been around here a lot lately, but these snippets of info are the reason I used to read this place all the time. Well, that and Todd's thoughtful dissertations. Although I had to wade through a few piles of dung to find these gems, I'm glad I did. Maybe if Todd has a Miller Light or two he can post without charging us!

PS if you have nothing constructive and/or useful to say, go throw your feces elsewhere

edit: Heat from deformation is definitely modelled in LFS as proven by Bob in a thread I'm too lazy to go find right now, but it would seem that core temps are not derived with enough weight towards it, and with too much emphasis on direct heat transfer from the surface of the tire. Even without having concrete values to work with (good luck), tweaking a couple of coefficients could probably move the heating model closer to being more "correct" than it is.

Quote from masternick :

good old elitist racers :rolleyes: grip is everything for drifting, why not get a good new tyre that will last longer and get more grip then some old cheapo tyre

Racing tires definitely don't last longer then some old cheapo tire. Why do you think they have to change their tires so much during a race? If you ran a race on street tires you probably would be able to go two or three races on them.

Jeff, as DragonCommando quite correctly says, the majority of heat generation does come from the flexing of rubber (I think with says 90% comes from hysterisis), when driving in a straight line. Rolling resistance values are fairly well known and seem quite well done in LFS - this heat generation is what makes the tyre sidewalls warm up.

What I don't know is how much heat is generated by the twisting and slipping of the contact patch over a surface. Clearly friction is an important factor here. If we take the 90% value from before, then when rolling along, this heat generation is taking about an order of magniture less energy than flexing (of a presumably well inflated tyre). How much it increases when a tyre is made to work hard is the big unknown.

Shotglass - could the fast heating yet slow cooling be attributed to a lack of cooling effect by the air, as the tyre passes through it? I would still expect a tyre to be heated a lot faster than it is cooled though.

Quote from wheel4hummer :

Racing tires definitely don't last longer then some old cheapo tire. Why do you think they have to change their tires so much during a race? If you ran a race on street tires you probably would be able to go two or three races on them.

They do last longer in drifting.

There is an exception though, there's one Chinese "Wanli" tire that lasts very very long, but is not up to standards with grip to tires like ie. r888. That Wanli was and is quite popular in Poland. Because it's rather cheap and lasts long.

And ofcourse used years old tires last very short. They lose thread (parts falling off) very quickly.

Quote from DragonCommando :

Like I said, the heat vs grip level seems to be somewhat correct, overheat a tyre and it performs like driving on ice. I have overheated tyres before in real life and that is how they act.

The point is situation like 4th gear <2000rpm dori, or oval drift on 5th gear with 250 hp xrt etc. will not occur in real life. I've checked a graph from lfs someone posted here showing how grip drops after tire heat. And Lateral G wise it seems ok, but spinning the tire wise not really. No matter how much you overheat the tires, this won't make your 170 hp car drift like 600 hp monster.

Maybe it shouldn't be even possible to reach the temps we reach in lfs and the problem would be fixed then.. As the tire would probably say sayonara before reaching those temps.

Quote from Bob Smith :

.....
could the fast heating yet slow cooling be attributed to a lack of cooling effect by the air, as the tyre passes through it? I would still expect a tyre to be heated a lot faster than it is cooled though.

I have long thought that tyres warm a little too fast and cool a little too slow. This would affect everything, no? the optimal driving style/heat/wear?
This combined with the scale of temperatures displayed which again i think would be/is incorrect itself in theory if the cooling is not effectivley reproduced?
What im saying is for example. The road super used optimal temp 55-65c Maybe this range of behaviour for given for the model is slightly short or needs more expansion? Without data from scawen or more infomation about how the system works. Its quite hard to really pinpoint somthing and say whats wrong with the tyres. Although at some point I do hope to see more infomation on work in that area, as do many of the posters and readers of this thread do i guess. But secret sauce is mmm secret.
Swiftly changing direction here with the tyres and not my steering wheel and looking a little forward. We know that the contact surface of the modeled tyre is broken into 3 channels across the width and divided 16 times giving 48 contact points for each tyre.
Interesting that the point of tyres falling appart being brought up a few times in this thread and ones in the past.
I'm guessing one day these sliced tyre segments could be used for LFS to have rubber fall off dammaged surfaces. (quick somebody wake me up)
Where was I, ahh yes. More segments perhaps could help the tyre physics? balancing out the load produced when "givin it some". (thinking aloud -i wonder what ratio of cpu usage is dedicated to tyres within LFS.)
I am no expert in the science behind the maths or vice versa or real race experience, but i do have a fair amount of LFS roadsuper experience and recall the first public S2alpha and a few subsequent builds thereafter.
Back then tyres were much much easier to pop faster to heat etc, then it is presently. Or was it my driving and car setup from s1 that created that
Its a long long time since ive tested or looked at infomation regarding the changes to tyres, or tested any old version, it could just be me and one of those days.It is odd though whilst typing this i swear it was 2006 for a moment. Perhaps its was, ....well it feels so long since there was a good discussion about tyres.
cue the whitemen in coats "were all going on a summer holiday"

Quote from kamkorPL :

They do last longer in drifting.

The point is situation like 4th gear <2000rpm dori, or oval drift on 5th gear with 250 hp xrt etc. will not occur in real life. I've checked a graph from lfs someone posted here showing how grip drops after tire heat. And Lateral G wise it seems ok, but spinning the tire wise not really. No matter how much you overheat the tires, this won't make your 170 hp car drift like 600 hp monster.

Maybe it shouldn't be even possible to reach the temps we reach in lfs and the problem would be fixed then.. As the tire would probably say sayonara before reaching those temps.

Yes, of course race tires last longer. They are designed to take more heat and don't have groved tread that wiggles more causing more heat. I am just surprised that specialized drift tires haven't been produced.

I think you are slightly missing the point about the grip and heat. As I suggested earlier, it probably has more to do with the grip model, and more specifically, with the way grip is regained once it is lost.

We think we know two things about the LFS grip model, one mostly imperical and one mostly a qualitative estimate. First, we are pretty sure that the longitudinal grip is not right. You can spin the tires like mad on acceleration, yet you still are able to accellerate out at as good, or better speed than a car that does not spin the tires. If you think about that for a minute, it might imply that even though the tires are spinning, they are still generating a lot of grip. This to me might imply that you are going to generate more heat than you realistically should.

Second, when a tire loses grip, it seems to regain it in a nice, linear manner makes things like the snap-back spin problem and other recoveries from slides a bit easier than it should be in some situations. This to me implies that once the tires break loose, it is easier than it should be to keep them broke loose. Therefore, you get the effect of a low power car being able to keep the tires spinning during drifting when you shouldn't be able to. I suspect it has more to do with the grip model than it does with the heat model, although the heat obviously does play a roll too. It is completely counter to the idea that spinning tires on start still allows you to accellerate quickly, so there is a lot going on here that we can't possibly know about (just like the real world, eh?)

So, yes, the heat modle needs some work, but it is pretty close as is. The grip model also needs work, but it is also very close, and dare I say still the most responsive and "realistic" out there right now. When you combine the two together while drifting, you do see some of the flaws a bit more dramatically.

(BBT, good to see you post again. I like you, don't post a lot anymore, but I can't resist a good discussion on tire physics.)

Quote from Bob Smith :

Jeff, as DragonCommando quite correctly says, the majority of heat generation does come from the flexing of rubber (I think with says 90% comes from hysterisis), when driving in a straight line. Rolling resistance values are fairly well known and seem quite well done in LFS - this heat generation is what makes the tyre sidewalls warm up.

Are you saying that you suspect then that heat build up in LFS is derived directly from rolling resistance at the tire; at least when there are no appreciable lateral forces involved? (Ie F=CN and just using that force as part of the heat generating code somehow). Just for my own edification to understand the idea better. It seems then you'd have to come up with an arbitrary number as to how much energy would be lost into heat via hysterisis.

Quote :

What I don't know is how much heat is generated by the twisting and slipping of the contact patch over a surface. Clearly friction is an important factor here. If we take the 90% value from before, then when rolling along, this heat generation is taking about an order of magniture less energy than flexing (of a presumably well inflated tyre). How much it increases when a tyre is made to work hard is the big unknown.

Well, clearly it plays a massive role at the surface. I'm mainly talking about the interaction thermodynamically between the surface of the tire and the core of the tire, which seems suspect to me. Perhaps one of the issues is that it's currently modelled as two distinct areas (at least from what we can tell) and should probably be treated more like a dynamic gradient. The air inside the tire seems like it's a better insulator than the core of the tire, which I wonder about as well.

Quote :

Shotglass - could the fast heating yet slow cooling be attributed to a lack of cooling effect by the air, as the tyre passes through it? I would still expect a tyre to be heated a lot faster than it is cooled though.

There is cooling effect via air even now. (At least according to a post by Kid ages ago, and he was in the know about shit).

Quote from Gener_AL (UK) :

Where was I, ahh yes. More segments perhaps could help the tyre physics? balancing out the load produced when "givin it some".

It was stated in the past that he'd tried different amounts of segments (seems like a thing a prudent dev would do) and that no benefit was seen from more.

edit: Good to see you as well Eric

Quote from Hallen :

You can spin the tires like mad on acceleration, yet you still are able to accellerate out at as good, or better speed than a car that does not spin the tires.

This has been posted so many times, yet my own testing in LFS has led me to the opposite conclusion. Excessive wheelspin does produce less longitudinal force in LFS, try the BF1 at the dragstrip with and without TC for evidence. Fastest times will be achieved with TC set at the optimal slip ratio. The question is that perhaps the dip after the peak isn't deep enough, doesn't happen fast enough.

Quote from Ball Bearing Turbo :

Are you saying that you suspect then that heat build up in LFS is derived directly from rolling resistance at the tire; at least when there are no appreciable lateral forces involved? (Ie F=CN and just using that force as part of the heat generating code somehow).

Actually, I'm sure I've read a post by Scawen that says that the energy required to flex the tyres is converted back to a longitudinal force or torque that becomes the rolling resistance. Hence very low tyre pressures will make the sidewalls overheat quickly and give you a noticeable reduction in acceleration.

Quote from Ball Bearing Turbo :

There is cooling effect via air even now. (At least according to a post by Kid ages ago, and he was in the know about shit).

I suspect that is modelled, although perhaps not well enough. I'd imagine that the humidity of the air would make a marked difference to the cooling effect, so that's potentially one possible avenue for improvement. Turbulence in the wheelarches might increase the cooling effect (or maybe even the opposite), and road tyres have a greater surface area than slicks, which must help, even if just by a tiny amount. We don't know how detailed Scawen's model for this is. Considering that we don't have hot brake discs warming the air that's cooling the tyres, LFS should if anything have tyres that warm too slow and cool too fast (although I couldn't say how large an effect hot brakes would have on the tyres).