Quote from tristancliffe :

I can apply pressure with my hands on my desk

*demonstates*

It is a force over an area. Just like a gas exerts a force over an area due to the pressure...

in phisics by definition pressure is only for gases/fluids it has the metric of force/area but its measured in pascal (and it is defined as "the air pressure at sea level"), for gases has no meaning talking about force, only pressure.
about your hands you simply apply a "force per area" (that is also not uniform), but that cannot be called pressure by definition

Quote from letdown427 :

OK, what I was trying to get across was:

If those graphs are showing the 'pressure' on the tyre. As in, they're displaying the force per unit area being applied to each part of the tyre by the road.

I didn't mean anything to do with the pressure inside the tyre.

Hope that helps a bit.

maybe now i understand your whole question...well the F9 readings i think are the contact area of the tire, in the entire discussion we used those readings to see how the weight (load) of the car distibutes over the tire regions

Quote from tristancliffe :

Pressure is uniform? Even if you model it over different areas??

You do realise he's talking about the pressure of the tyre on the track, not the internal pressure?

pressure is by definition a gas/fluid thing, on tarmac there is "force" not pressure...well there is the pressure of air, but i don't think that's what he intended

EDIT: he inverted the force and pressure concepts (using force for internal air, pressure for tire against tarmac), so the reasoning should be the exact opposite as he did

Last edited by Honey, Tue 25 Apr 2006, 13:04.

Quote from letdown427 :

Nobody had any thoughts on my point about the fact the F9 readings display pressure?

Pressure being the force per unit area.

LFS gives three 'areas' in F9 view, left edge, flat middle bit of tyre, right edge.

Would it not be feasible that the pressure is so much higher on the sidewall reading because the sidewall area is so much smaller? So even if say the force was the same on the middle and the left edge of the tyre, the left edge would be experiencing a muc higher presure.

sorry i wanted to reply but forgot...

pressure is uniform, F9 readings should be the mechanical load against the tarmac

Quote from ussbeethoven :

Hello,

I think it would be nice to have ramps avaible on more tracks, could be fun to jump with 300km/h on Kyoto. Maybe it didn't need to much work to make this possible.

Quote from avellis :

I had also proposed previously More stunts-friendly options: Objects, check lines etc.

absolutely yessss!!!!!!!!!!!!

if someone raced on the blackwood reversed at StuntRacingServers, should know how much challenging and fun it is...

Quote from Hyperactive :

...
Not that I make the decisions, but if there wass better time to make a change it would be now (just a friendly suggestion)

i totally agree!!!
nobody expected that the patch was perfect, if something has to be fixed it's better now that hotlaps are just started, than erasing them after that many people spent many efforts in hotlapping challenges

Quote from Shotglass :

hmm cant get my head aroungd the whole bias ply vs radial thing atm (im totally concentrating on group theory and channel coding atm ... got an exam tomorrow)

but just a quick observation for now ... its probably related to the general consensus that lfs tyres feel somewhat like bias plys

think to your exam is much more important

btw with the previous images at linked page i meant that either way lfs model is incorrect

Quote from NotAnIllusion :

I've probably lost track of what the discussion is about, all I really want to know is that with a stiff suspension, about 31 PSI pressure and -2.5 camber for the left front, in normal race driving, is it usual (read: possible) for the camber (or w/e it is in F9) to be as it is (more on the sides than middle) and should the tire temps be as they are (more on the sides than middle)

in real life it's definately not possible...and that's all the dicussion about

Quote from letdown427 :

I'd have to disagree with that, for a few months, I worked as a Marshall at the Bedford Autodrome, and had a good days hands on experience with used slicks from the Formula Palmer Audis.

I'd say the opposite is very much true in those cases, the sidewalls were very very stiff, and the actual flat slick bit was much softer in comparison.

As for road tyres however, the difference doesn't seem quite as severe, however I don't have the same amount of experience handling un-rimmed road tyres as I've had with those slicks.

slick/race tires are a whole different thing and i specified few times that for what i saw until now slicks are much better modeled into lfs

the images in this page http://www.rsracing.com/tech-tire.htm
show why i think the current lfs model is very wrong

Quote from Shotglass :

hmmm you really pinpointed something there that always struck me as odd in screenshots but i couldnt lay my finger on it ... it really looks like the sidewalls are streching out instead of merely deplacing whic i assume would be the correct behaviour with all the reinforcments in them

i mean that from graphics it seems to me (i can be plain wrong) that the contact part is stratching, like if the outer part disappears

Quote :

inner part when cornering in a way that loads the inner or lifts load from the inner part ?
i assume you mean lifting load from it ... but either way i think your wrong about the cetral part being the least deformable ... imho its the most deformable with the sidewalls and the sidewall/inner/outer transition being the stiffest parts of a tyre

i meant: outer load > central load >> innner load (considering high deformation/displacement)

if you ever "played" with a tire out of its rim you could have experienced that the contact part is very hard to deform, the sidewall is very easy

Quote :

dont forget that with high neg camber the insides heat up considerably under acell and braking

yes, i considered, but i think i should repeat tests being sure to avoid these effects to have a more objective result

Quote :

imho the effect of pressure on deformation under centrifugal forces should be rather slim

actually it is, but could also be easy modeled with a fictional incremental tire pressure that varies with speed...imho its irrelevant to our discussion

Quote :

not sure if i i fully understand you but in case i do i dont think the model is necessarily wrong as such but its an effect caused by the simplification of using only 3 sections across, two of which are more or less directly connected to the sidewall which should cause the sidewalls to have much more effect on contact patch deformation than it has irl

having only 3 sections is not an issue to me, more will only mean more accuracy,what i say is taht it seems to me that the functions behind the three sections are wrong or wrongly tuned.
about sidewall effect on tire load, that is what it is wrong, it's definately excessive, especially for a wheel with small rims like the xfg

Quote from mrodgers :

What the heck kind of enjoyment would they get out of that? Sheesh! I don't get anything in return for winning a race no matter what. I don't do this professionally and get paid cash. I do get immense satisfaction of battling against someone for an entire race and beating him in the end, not neccessarily for first place. I get immense satisfaction on following someone I know is much faster than me and staying on their tail for an entire race. It's what the online racing is all about. Who cares if you come in first?

what can i say evidently some people live for charts/stats, i agree it's no fun or honor to win like that, i always preferred an enjoyable close clean fight, rather than a lonely victory, also following a faster racer teaches a lot of things, while waiting behind a slower one on a difficult to pass track teached me a lot on how to prepare a safe pass...i guess those people don't even know how much fun they are NOT having

Quote from Shotglass :

...
the idea is that the loads on the inner and outer parts of the tyres are to a large degree influenced by sidewall rigidity whereas the load in the middle is mostly influenced by pressure

my concerns are that if this is true int lfs tire model (as it seems to be) its sadly wrong, because even at very low pressures (let's say 1.6 or 1.7 bars) those effects, must not show at all, but it must rather be "simply" pressure/compression problem

Quote from Shotglass :

left/right being inside or outside of the tyre ?

left is outside right inside considering the left tire while cornering right...hope i made myself clear...sorry

Quote from Shotglass :

its really hard to say where exatly the problem arises ... maybe its just some parameter (like cetrifugal forces ... yeah i know it a virtual force yadda yadda) missing and the models works better than wed expect right now hard to tell when going just by looks without any hard data on how the tyre deforms

when said behaviour happens its usually with positive momentary camber (check shift-l to see live camber) (main "geometric" load on the ourside) and significant outer-sidewall deformation
now if we assume that the inside sidewall deforms less than the outside the contact patch has do fold somewhere which happens to be towards the axle most of the time

your considerations about shift-l data and guesses, seem to confirm a graphical thing: the tire seems not to displace, but rather stretch...if it really so (in lfs) then the problem could be that the inner part is not deforming, while in RL the displacement of inner part makes the inner part "lift" even at very low pressures...considering that the central part of a real tire is the biggest and the least deformable, it always have much more load than the inner part (let's remeber -> when cornering...)

the point is that when cornering even at quite low pressures (let's say 1.6 bar) the normal situation is (A) with the new patch at almost every tire pressure the tire load while cornering is (B), which is phisically impossible.
and please consider that (B) into lfs is much more exaggerated, here i made it small for clear purposes.

also if you put much negative camber and do some fast laps you will see that is not the left part that heats up but only the right one and that's another very odd thing because of a bad discrepancy inside the lfs tire model (that wasn't so with the previous patch)

Quote from Shotglass :

i can second the little oddity in the loads you see on usual road pressures too ... hard to say whats wrong in the model though ... maybe its just the lack of balloning from rotation ... maybe something else

it's "just" (mainly) the biasing of the function that relates pressure to tire load; in previous patch was almost correct, now it's always working as the tire had a very very very low pressure.
what makes it really odd is that the function grip/pressure has totally opposite bias comparing to reality, so basically it is no longer possible to find even fictional settings in lfs to make the car behave like in real life

Quote from KiDCoDEa :

even with aero simplified (for lfs aimed standards) i still dont see the few people that complain about it "being easy", being competitive in the charts...

"interesting" that you say i'm wrong about lfs tire phisics because i'm not in the top charts of formula cars...moreover, fast has nothing to do with phisic knowledge (strange that nobody asked me to prove i'm fast when i graduated as engineer or when i passed the exams for inscription at the professional engineer's book...), moreover "easy" not = "fast", moreover i'm talking about xfg, moreover if you see my old stats, you will see that 50% of races i was on the podium...i think it's not that bad for a girl like me who spend only few hours per week at lfs...
if you can prove that i'm wrong please humor me...

sometimes i saw three guys doing a dirty team tactic:
the first go faster as he can alone, the second and the third crash everyone's trying to pass and on straights they put one behind the other using slipstream BUT the third instead of passing the second it bumps him to get both higher speed, but as i said if someone is fast enough to catch them they will crash you, each race they switch roles...

Quote from NotAnIllusion :

The point is that it happens even at 2.2 bar which according to Honey (I don't know, don't blaim me if it's not right ) is the max recommended pressure for that type of car & tires.

It does happen at 2.2 bar, I know because I tried it in LFS. I went all the way to 2.8 bar when it stopped happening but the result was that even with optimal temps and -2.5 camber for the fronts and -4.1 for the rears in every single corner at Blackwood GP, and even if just gently swinging left and right on a straight the slope of the live camber inverted and a huge amount of understeer one doesn't get with lower pressures.

I don't know enough about tires to draw realistic conclusions, but what I do know after trying out with road_normals and slick2s is that there is no advantage to running with higher (realistic?) pressures, in fact I still did significantly better with low pressures one would have used in the P/Q patch.

Oh and found an interesting link
http://www.toyo.com.au/Pit%20Lane.htm

thank you for taking the time to actual test it and answer honestly.
actually recommended pressure for an xfg like car is 2.0 bars, 2.2 is the maximum recommended.

this patch feel much more unrealistic on road tires because this huge problem with the new deformation model joint with previous problems (unrealistic maximum grip at very low pressures + unrealistic temperature/grip model for road tires) make this patch very weird and this only problem of deformation cancels the others huge improvements of this patch.

i really hope scawen talks a bit more about the tire model, so that feedbacks can be more precise and constructive and better let's all hope that the recent agreement with intel/sauber/bmw/michelin opens the doors of more technical data to lfs also for road tires.

Quote from Ball Bearing Turbo :

Honey, the phenomenon you describe about the middle part of the tire is attainable even in a straight line on a real car - with too low a tire pressure. I don't know if it happens for the same reason during cornering, but that shows that it's not physically impossible for your "vacuum" (although it's not) effect to occur IRL.

it happens at very low pressures when pressure is comparable with other forces and the tire model is much more complex and as i said that's not the case i'm talikng about, even at slighly low presures it must not happen

Quote :

Casual drag racers often lay a patch just for the purpose of observing the said patch, looking for the phenomenon you desribe, or the reverse (for over inflated tires). I don't know if LFS models (nonexistant) centrifugal force on the tires, I thought in a thread somewhere that it did, but I was informed that it does not. That may account for something.

i'm talking about road tires not slicks, i precised it from the beginning

Quote :

We also do not know if the visual representation in LFS is precisely what the physics model is generating... What I mean is that the graphics engine may or may not relate to the physics with 100% accuracy. In terms of the "amount" of deformation, I realise it has too, but I mean in terms of the structure of the tire.

infact i repeated many times that my guesses came from the F9 info wich are representation of the dynamic tire phisic model of lfs

Quote :

Pictures from RL don't show much for either side without the appropriate information unfortunately, and we can find pictures that seem to prove either side but they prove nothing really.

from the inclination of cars on screenshots it seems that they were taken at high lateral G

Quote :

And honey, driving at 50km/h is not relevant. You can still generate massive forces at 50k, 100k, whatever. I'm tempted to mount a camera on my car and find an empty parking lot hehe

i believe that when you drive into traffic you and other people are not driving at maximum G, compare your usual driving with a similar riding into lfs and watch replay with F9 info

Quote from TaiFong :

*BUMP*

I just wanted to bump this thread back up again now that the new patch is out. I haven't done much extensive testing, but a few passing tests have led me to believe that the tires act pretty much the same way as before. I get bad understeer with ~40 psi in road tires and I feel much more in control if I drop it to below 30. Still is a bit odd to me. I cannot really feel any decent rigidity out of high pressure tires...just a nice plow!

Anyone have any additional comments after patch T has come out?

you are right! the pressure/grip relationship is still as before or even worse (with road tires), what has become even worse is the new deformation model that requires the maximum tire pressure lfs allows to get phisics behave less unrealistic, put also that the temperature/grip relationship on road tires is still wrong and you got this ugly unrealistic patch.

for slick tires it all seems good (but i dont have real experience with slicks) and i guess it because of BF1 (i assume michelin gave the devs the telemetry data for slick tires)

Quote from Funnybear :

If you are using old setup tyre pressures with the new patch physics then I think you will get anomalous readings. With the new 'grip' factor I think you will find that the setups will adjust to a more realistic setting with stiffer suspension, higher tyre pressures and less camber. This will lesson the immeadiate effect of how you see tyre deformation now. Of course a low pressure tyre will defrom to large degrees, it's got nothing to hold it up.

I think a discussion of this nature needs a few more weeks of 'gametime' maturity before exhaustive critism can take place effectivly.

if you read my posts or even just one of them you will see that i already doen the tests you suggest, how funny that everyone's says i'm wrong but nobody dare to take some test and discuss about the results, moreover none seems to take care of the real screenshots posted above, all real picture show evidently even at the most first view, how the lfs deformation is wrong -> causing huge phisic unrealism.

Quote from axus :

I find it happens on a far more rare ocassion now, before it had gotten to the stage that the problem was predictable. Now because you don't know the conditions which bring the same problem about, you don't know when to expect it so it seems like not much has changed but a lot has.

i'm not sure i understood well what you say, but as i said in the other thread: take xfg put 2.2 bar and 3.5 camber (in RL you would never do such much) and drive around BL or SO at 50 kmh with F9 info and tell me if it is absurd or not

Quote from axus :

the problem is now quite easy to ignore because it doesn't appear under most driving scenarios that occur in proper racing. If you try to provoke it you will still get to it though.

actually is the contrary: it always show up too evidently in normal conditions, that's why i'm spending so much words, everyone is caught by the "BF1 fever" and nobody is testing the slower cars...the few glitches in tire phisics are ruining this patch wich is at 90% a huge improvement