Oops 
The combined curves are on road super rear tyres at 240 kPa (iirc) driven with the XRT.
Whilst bias-ply (or crossply as they are known in the developed world) are more forgiving, they are not less sensitive to camber.
The stiff sidewall means that you have to keep the tyre as upright as possible at all times - you cannot run more than about -0.25° negative camber without the shoulder overheating and the sidewall giving up.
Radials, with a much softer sidewall, are vastly more tolerant of camber, and can be run up to about -6° static camber without too many problems (depending on budget and required tyre life).
So to reiterate the curves are taken with low profile performance tyres at reasonable pressures.
With my very limited amount of knowledge on tyre behaviour i would expect them to peak much earlier more like on the texbook graphs, which peak at about half the peak slip angle observed in your tests.
Lots of food for thought at that sight
thanks for posting Niels http://insideracingtechnology.com/disccosmo.htm
On reading the above commentary and with what I have observed in LFS I have a gut feeling that any improvements in LFS tyre physics will come from tunning tyre load sensetivies.
Currently in LFS loading up the outside tyres produces more grip (with driver position and stiff ARB) this is clearly a no no IRL, so points to a likely flaw in LFS's tyre physics in regard to tyre load sensitivities at the limits of grip. This could be having an effect on longitudinal as well as lateral grip.
Also this could well be closely linked to the tyre pressure issue in LFS now, as with low pressures I'd assume should exaggerate tyre load sensitivity issues but in LFS you seem to get more grip no matter how low you go
My guttometer is telling me that while the overall traction levels in LFS seem about right the individual tyres aren't. Which is why you see such strange setups compared to RL.
What do you think?
I mixed up the camber sensitivities for cross-ply and radial tires. My bad.
I'm going to have a leaf through over dinner for any more useful and interesting information. I'm looking through at the moment a section on abrasion. (especially in the case where cold tires are pushed beyond the limits of grip. Interesting stuff.
There is a section on tire load sensitivities. This is important, because tires, in their massive complexity, don't produce grip linearly with load.
From personal experience, driving reasonable road tires at 235/40/18, 32psi, and dicking around, and well past the limits of traction, I'd say the tires snap back sooner. I'd say LFS's physics are spot on for wet roads, with the traction multiplied up a bit, if you get me. But I am by no means any authority.
I'm going to have a leaf through over dinner for any more useful and interesting information. I'm looking through at the moment a section on abrasion. (especially in the case where cold tires are pushed beyond the limits of grip. Interesting stuff.
There is a section on tire load sensitivities. This is important, because tires, in their massive complexity, don't produce grip linearly with load.
From personal experience, driving reasonable road tires at 235/40/18, 32psi, and dicking around, and well past the limits of traction, I'd say the tires snap back sooner. I'd say LFS's physics are spot on for wet roads, with the traction multiplied up a bit, if you get me. But I am by no means any authority.
I'd agree with that. There is a 'snap' missing in LFS as you 'regain' grip, and your wet weather scale up isn't far out in that respect.
I don't know if load sensitivity is modelled, but I imagine it is - having load versus CF versus grip isn't the hardest thing to do, and from those curves the behaviour is automatic.
I don't know if load sensitivity is modelled, but I imagine it is - having load versus CF versus grip isn't the hardest thing to do, and from those curves the behaviour is automatic.
if it werent modeled suspensions setups wouldnt work and arbs would be utterly useless for finetuning
and they work just as youd expect them to in lfs
*cough*A chirping bird once told me*cough* that it appears to be modelled but it's not pronounced enough. I don't know much on it, really.
I think the other area of concentration should be tire temperatures and pressures. This might be a side effect of the load sensitivity issues or other issues, it is hard to say.
But, what do we do in LFS if you need to decrease tire temps? You raise the pressure which seems to be opposite of what you would do in RL (Tristian... is that generally true?). You also reduce camber some.
IRL, lower cold pressures allow more pressure build up in the tires, and the tires stay more cool throughout a stint. In LFS, this is not true.
Also, tire heat seems to build up and not dissipate quickly enough. I am not really talking about internal temperatures, but the surface temps. Watching an F1 race, they had a new graphic this year. The graphic showed tire temps. Going through a long corner, you would see the temps rise quickly. Then, on the subsequent straight, the tires would cool quickly. This does not happen in LFS.
These problems might also have an effect on the longitudinal grip problems that we see.
These are just my thoughts, there are no scientific studies that I have done.
But, what do we do in LFS if you need to decrease tire temps? You raise the pressure which seems to be opposite of what you would do in RL (Tristian... is that generally true?). You also reduce camber some.
IRL, lower cold pressures allow more pressure build up in the tires, and the tires stay more cool throughout a stint. In LFS, this is not true.
Also, tire heat seems to build up and not dissipate quickly enough. I am not really talking about internal temperatures, but the surface temps. Watching an F1 race, they had a new graphic this year. The graphic showed tire temps. Going through a long corner, you would see the temps rise quickly. Then, on the subsequent straight, the tires would cool quickly. This does not happen in LFS.
These problems might also have an effect on the longitudinal grip problems that we see.
These are just my thoughts, there are no scientific studies that I have done.
Just to make sure, when you refer to "surface temps" in LFS, you mean the F9 view with shift+ctrl pressed, do you? If not, you're not looking at the surface temps but at the rubber inner temperature.
Indeed. They do rise very quickly on the surface in a corner; but I do agree that the "rubber internal temperature" doesn't fall quickly enough for some reason.
I don't really know.
We asked Avon what a recommended hot tyre pressure should be, as was told 20psi. So we just set our cold pressures to reach that after a run (which works out at about 15psi on the more loaded side and 16psi on the less loaded side, depending on the track of course).
Measuring temps across the tyre generally seems to show reasonably even temps, with a slight peak in the middle - perhaps we need to lower the hot temps, but Avon said that was normal and okay when we showed them our data.
But we haven't used pressures to control tyre temps. Or camber yet. If our tyres get too hot we'll cope some other way - perhaps spring rates, or perhaps saving up and buying a slightly harder compound of tyre.
You need to ask a professional racer/tyre person this sort of thing, as it's out of the depth of most club racers (ourselves included) due to lack of track time.
Yes, I mean the ctrl+shift F9 temps, but also to a degree the internal rubber temps. Heat transfer seems to happen too easily to the internal rubber, and the surface temps don't cool as quickly as they should. The interanl temps get hot to quickly because of the fast heat transfer, but don't seem to cool as quickly as they should either.
Good answer. I guess the important thing here is that each type of tire has an optimum hot pressure that they should run at. In the LFS case, it is the lowest pressure possible where your tires don't overheat. I think that is a bit odd.
Secondly, you said it yourself. You use 15psi cold on the loaded side and 16psi cold on the less loaded side. So, you are not using pressure to control temperature, but are using temperature to control the hot pressure. This is again different than in LFS. In LFS, we use pressure to control temp and to some degree the other settings you talk about, but not so much.
Thanks!
Agreed; and not enough in the opposite direction - ie heat is not taken away fast enough from the internal rubber.
Really? After a corner it only takes a second or two before the surface temp is down around / below the internal rubber temp. You think it should be even faster?
Hang on.. a material's heat conductivity is irrespective of the direction of heat flow..
Or were you talking about something else?
Or were you talking about something else?
No, that is what we are talking about. It shouldn't be that way because of your point.
Hmm, maybe I will look at that closer. I could be wrong there. I don't look at surface temps all that much.
Regarding temperatures it's on the surface that they don't cool fast enough. Maybe the effect of the varying air speed isn't modelled?
EDIT: you can get an example of real life tyre surface temps if you download i2 pro from the motec website. There's a sample file included but I don't know what car that is.
EDIT: you can get an example of real life tyre surface temps if you download i2 pro from the motec website. There's a sample file included but I don't know what car that is.
Exactly; that's the whole issue as far as I can tell.
The tires (on the surface) cool down faster at very high speeds. The surface temp is a number of degrees below the internal temp if you spend any time on a straight at good speed. This is even more so on the open wheelers as well, and wind affects it too (Kid posted that ages ago)
still you dont really get the feel that the tyre loses energy in the process theres something about the surface temp modeling that just doesnt sit right with me and apparently many others here
btw just 2 pages in and were already way off topic
That is exactly how I feel the tyres in LFS also at this stage. I wasn't susjesting load sensitivity wasn't modeled in LFS just that it possibly could be the next thing that gets fine tuned and that it probably is linked to a more complex contact patch simulation
In my thinking if you put a car side ways in LFS the tyres have grip loss that is linear which causes a more gradual shift in wieght. In RL once you have gone past a certain grip level the grip loss is no longer linear on the outside loaded tyres and therefore the wieght shift is more dramatic which causes the snap back. What do you think?
Also I was under the impression that in LFS we currently frequently run higher than real life settings for ARB? So put that down to tyre load sensitivity not being severe enough
As ARB seems to be used more for driver feel of car than achieving optimium grip in RL. In RL they seem to consider much more the grip of all four tyres were in LFS alot of the fast setups pretty much discount the inside tyres of a corner... thoughts please 
That's always a danger when raising a topic related to tyres
Tyres are so complicated in their behavior that there is no such thing as "off-topic".
Have you people ever heard of the term "it's so tight, it's loose" used before?
I don't think the fall off in traction with slip angle is pronounced enough for radial tyres because this behavior seems missing, kind of nulled out.
The effect I'm describing is when you understeer into a corner at the limit of effective slip angle, and then due to a surface change or steering input, going past the slip angle, when grip rapidly falls off, this brings the rear tyres up to optimum slip angle as they experience more lateral force as the fronts start letting go more.
the problem comes when you come back down the slip angles at the front assuming you made the corner, at which point you have to correct ultra fast as the front tyres snap back into their prime biting slip level...
I get the impression this is far less pronounced in LFS as it is in real life, although it could just be down to me having a naff wheel without 720 degrees of lock. Looks kinda like this:
http://www.youtube.com/watch?v=RuBlF6Aa8dc - I didn't think anyone in a nova could drive this well!
I had this happen in my car, and promptly tank slapped into what I've started calling "a minor off", because it sounds better than "parking off road" (my previous term) and much better than "I crashed into a ditch". (That'll teach me to think I'm the freakin' stig and turn off the DSC - http://www.youtube.com/watch?v=ncE-Vk7egRo)
Have you people ever heard of the term "it's so tight, it's loose" used before?
I don't think the fall off in traction with slip angle is pronounced enough for radial tyres because this behavior seems missing, kind of nulled out.
The effect I'm describing is when you understeer into a corner at the limit of effective slip angle, and then due to a surface change or steering input, going past the slip angle, when grip rapidly falls off, this brings the rear tyres up to optimum slip angle as they experience more lateral force as the fronts start letting go more.
the problem comes when you come back down the slip angles at the front assuming you made the corner, at which point you have to correct ultra fast as the front tyres snap back into their prime biting slip level...
I get the impression this is far less pronounced in LFS as it is in real life, although it could just be down to me having a naff wheel without 720 degrees of lock. Looks kinda like this:
http://www.youtube.com/watch?v=RuBlF6Aa8dc - I didn't think anyone in a nova could drive this well!
I had this happen in my car, and promptly tank slapped into what I've started calling "a minor off", because it sounds better than "parking off road" (my previous term) and much better than "I crashed into a ditch". (That'll teach me to think I'm the freakin' stig and turn off the DSC - http://www.youtube.com/watch?v=ncE-Vk7egRo)
Part of that is due to the way we set pressures. Tristan has different cold pressures so that hot pressures are the same and lives with the difference in temperature.
In LFS we set hot pressures so that temeratures are the same. The effect of pressure on grip was really pronounced back in patch P but now temperature seems more dominant. And IIRC, camber is more important than either.
yes because it doesnt exist in real life
which it doesnt
and they wont do that either
you realize this is happening at a transition from mud to tarmac when naturally the fronts are on much grippier tarmac at first
which btw means he cant drive well at all
hm how did you find that one out ?
How does LFS's longitudinal tyre physics compare with these?
(123 posts, started )
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