Recently I have starting to take a closer look at the physics and design of the cars in LFS in an effort to try and understand why the street cars in some cases do not feel as good as they did in S1 and why often times setup changes do not have the effect on the cars handling as I think they should. Some of the things I observed while doing this have made me rethink my approach to car setup but I still do not know enough to really make any hard assumptions. Up to this point I have gone back and forth on whether even loading or even temp is the best solution for tire grip. I am still torn on the subject but I am starting to think that either is just as important as the other, but the current model does not allow one to achieve both even heating and loading, you have to choose which you want to use.

Then next thing I started playing with was tire pressure. I am convinced that some of the handling issues stem from under inflated tires. So I took my set which now felt good and handled the way I liked and added 10psi to the tires in an attempt to try and reduce sidewall flex with out and regard for its effect on tire heating but retaining the camber needed to keep tire heating even. The result was that the car became extremely responsive to input, so much so that I actually got the car to do that snap back to straight on a throttle lift that we all know happens in a real car when you get the back out of shape. I found that it was almost too responsive though and I was still getting more sidewall flex that I wanted.

At this point which the tires starting to behave like I expect them to on my real car changes to the other setting also started to have the effects I know they should. Over damping with the shocks became a liability were before it was necessary to help add responsiveness lost do to soft tires. Adjustments to springs rate started to have the desired effects, when before they seemed to have very little effect. In the end I found that when setup in this way the car now feels like my sporty car instead of like my truck with its narrow, tall soft tires.

So my questions to the community are thus:

Is it more optimal to achieve even tire surface heating or even surface loading under cornering to achieve optimal and predictable handling?

Is it more optimal to have tires running at optimal temp or to have enough pressure to prevent the sidewall from rolling on its side?

Would it be better for online racing for people to use setups based around real world ideas and have a slightly slower more predictable car then a faster car with a much narrower performance envelope?

And lastly what have the rest of you observed in terms of how the cars in LFS compare to cars you drive in real life? Do they handle the same and do changes have the effects you think they should?

I think the tire model and suspension model has come a long way, and one of the most impressive models in a simulation if you compare to others.

The only downside I think there is right now is the damage modelling to go with the suspension. We can still hit curbs pretty hard in formula cars (or any car for that matter), and not much damage is taken on. And any car really needs to have the possibility of having a wheel fall off or losing linkage completely. The same applies to the body damage and things like wings on the formula cars. It's the only thing to make the game feel even better, and allow the physics to become more diverse.... rather than it just be temporary/driveable damage and everyone going around beating everyone up. LFS is becoming more and more serious when it comes to its physics, but the dissapointing part is that it needs to take big steps in development for it to happen .

There are a few suspension models that are not yet implemented (like one for the FZ50), and there needs to be a lot of improvements that will add to the realism of driving a car...

-Rev limiter is wrong in LFS
-Ignition acts like a motorcycle ignition
-Insanely high camber values on road cars (upto -5 on XRT for WR, wtf!!!?)
-Low speed physics is still getting better, but there is still not a lot of resistance when doing starts, and crazy wheelspin is still faster for accelerating.
-I still think higher tire pressures is being simulated a bit too extreme for lower grip levels

I bolded that because I would much rather have a narrower performance envelope to allow players to have pretty respectable setups, and not have something drastically different. As long as you feel the differences from one setup to another, that is what I like about LFS. But some things are a bit too extreme that is results in very negative or positive setups.

Quote from Gimpster :

but the current model does not allow one to achieve both even heating and loading, you have to choose which you want to use.

So I agree on this point. In a real car, the higher tire pressures can be more effective for highspeed driving and stability, LFS just makes it feel more understeery to a point where you are forced to lower the tire pressure in order to be faster, yet somehow very low pressures have no sign of 'sagging'... only heating under high loads or scrub. I also don't think LFS simulates tire pressures rising as the tire gets hotter, I really never feel any of that. GPL had it, and it was great.

Well, the only driving I've done is pulling the car into the garage. I will come back and comment when I get my learners permit.

I think you've missed the point about tires. Softer pressures will give more grip and higher pressures will give you less flex and a more responsive car but less grip.

Quote from Tweaker :

-Insanely high camber values on road cars (upto -5 on XRT for WR, wtf!!!?)

have you ever seen pics of old touring cars ? like from they days when they were still roadcars instead of spaceframes with carbon that looks remotely like the road car ? those cars did use some insane camber granted they ran on slicks but still a race tuned road car needs loads of camber

Quote from ajp71 :

I think you've missed the point about tires. Softer pressures will give more grip and higher pressures will give you less flex and a more responsive car but less grip.

I still think the difference between the two are far too extreme.

Take a car and give it super low pressures and do a u-turn. Even then it has some poor grip and understeer. Raise the tire pressures and do a slow u-turn, it has way more understeer, even to a point where you cannot keep a tight radius at all. It's absurd.

Doing the same thing at highspeed is just running on an even high curve of losing grip. Softer tires somehow make it surprisingly easy to turn at high speeds with hardly any scrubbing... when you know it should be sagging and creating understeer. The tires we have are not low profile or anything, they seem to be modelled like economy tire sidewalls. And at high speeds with higher pressures, the grip is just lost the moment you turn the wheel, and not even when the car is loading weight on them. The tires are not supportive, they are just basing their lack of grip off of how high the tire pressures are, as if there was an extreme loss in tire patch illepall

Quote from Shotglass :

have you ever seen pics of old touring cars ? like from they days when they were still roadcars instead of spaceframes with carbon that looks remotely like the road car ? those cars did use some insane camber granted they ran on slicks but still a race tuned road car needs loads of camber

Yes, but have you seen the roadcars in LFS with insane cambers, and the camber is not even returning to a neutral point (0 deg) while in a turn? I just think that the high cambers are exploited because any grip used on the outside of the tire is useless and results in poor grip.... when hypothetically you should try and get a flat & full tire patch through a corner, right?

Example, XRT WR at Blackwood.

Here is a picture of it going through the hairpin. A few things you should notice:

Low tire pressure & setup uses nearly -5 camber on the front and the wheel isn't even straight up, yet the tire's outside wall is looking very stressed out from high loads on the OUTSIDE????? Not to mention, the force bars show it is creating the most OPTIMAL grip at the same time (green bar) illepall

EDIT: Same situation in the 2nd pic. The fast right hander after the straight. Camber is no different, yet there is optimal grip at very high loads with soft tire pressure, AND extreme amounts of sidewall flex.

So what is there too conclude??? That a high -5 camber in the front can carry you through a corner while the other ones cannot? :zombie:

What I find strange is, even though road cars have very grippy tyres now (1.2G) and are harder to spin in a straight line, it takes the effort of a feather to make cars oversteer with ever so slight steering thrown in. There is a big error / bug / wrong data somwhere imo.

To a point yes. But is a tire rolled over on its sidewall more grippy then a tire still frimly on its contact patch. One thing that stood out to me when learning to autocross was that they told us all to increese the pressure in our tires before coming to the event. They made a point of emphisizing that preventing tire rollover was the most important thing to achieve in tire setup. Optimaly you want to run just enough pressure to prevent the tires from rolling on to the sidewall under max cornering force. I don't see that as being the case in LFS. Tire manufactures allso would not design a tire that would require a pressure so low as to make the tire dangerous to achieve the optimal running temp, yet this seems to be the way it works in LFS currently.

When I was testing the FZ50 using a low camber, medium pressure setup I found that the inner tire temps on the back of the car and the tires surface temps were performing like i imagin they should. The right side of the tires got warm on left hand turns, the left sides got warm on right hand turns, the centers heated more and the sides cooled on the straights and under acceleration and braking and the overal effect was very dynamic over the course of a lap. But to achieve this effect the tires end up running at about 5-10C below optimal and sidewall fles was still a little bit of an issue.

The car also responded to smaller inputs and was over all much more responsive. I think though that the benifts of using a more realistic setup like this is still not being rewarded enough in the way the physics work, as it is plainly clear from the WR sets that the fastest sets are nothing like would be used on a real car.

When I look that the way the tire loading on the contact patch affects heat generation i see a problem and it may be a contibuting factor. With the pressure set right to develop optimal head at the center of the contact patch and camber set to allow the bst grip in cornering the inside of the tires run very warm 10 ro 20 above optimal and the outer edged loose heat. The entire contact patch is still touching the road, and is generating friction yet the outer edges don't generate any heat and thus never generate thier optimal grip. I think that the there is a decmel misplaced in the calculation that in effect looks somthing like this. Heat = Load % * Friction, when maybe it should be Heat = (Load % + 1)*Friction. Even a tire running at -5 degrees camber should be building heat in the outer portion of the contact patch, though friction, heat exchange from the inside air temp and throguh the media of the tire as well. There should be a blead effect to some degree by which the less used portion of the tire helps cool the warmer portion and vice versa. I only see this happeing when a much less sever camber and higher pressure is use. This tells me that only when the relitive differences are small does the system work, so somthing is getting multiplied to the wrong power in my opinion. I need to explain that better but I am not sure how to yet.

interesting thread, nice pics Tweaker. Hard to know whether those pics are representative of the deformation occuring within the physics engine, or whether they are just a graphical thing though? Would be nice to get a shot of a similar 'real' car, without the car there also hahah.

I used to create setups aiming for a fairly even distribution of temperature, at least on the 'heavily used' side of the car - but I'm finding lately that more negative camber is better, and forget the big temp difference. Heat does seem to take a very long time to bleed through the tyres - I wonder whether heat is only transferred between outer tread and inner air, rather than from outer tread to outer tread? Have no real data to base any of those thoughts on.

just like Wheel4Hummer, i would comment, but my driving experience in real cars has never pushed them anywhere near the limit (except emergency stops, but then it didnt have abs, so i couldnt really "feel" anything), and karting doesn't help when we have no karts although from my experience with karts and dirt on their tyres (regular occurance for me !) seems realistic as it does take a fair while to get it off (infact LFS does this a bit quick if truth be known)

Quote from Gimpster :

I think though that the benifts of using a more realistic setup like this is still not being rewarded enough in the way the physics work, as it is plainly clear from the WR sets that the fastest sets are nothing like would be used on a real car.

some guys posted setups, in the section, that were to have real cars specifications. but they didnt wear flamesuits

you can try

i can see there easy-going-setups sticky, there were road-going-setups (with some strange gear ratios as i remember, maybe other things) sometime go but i wont use "search".

Quote from Jakg :

although from my experience with karts and dirt on their tyres (regular occurance for me !) seems realistic as it does take a fair while to get it off (infact LFS does this a bit quick if truth be known)

what about time neded to cool the tires, it takes quite a lot and i dont know how it is in reality.

Quote from Blowtus :

interesting thread, nice pics Tweaker. Hard to know whether those pics are representative of the deformation occuring within the physics engine, or whether they are just a graphical thing though? Would be nice to get a shot of a similar 'real' car, without the car there also hahah.

I used to create setups aiming for a fairly even distribution of temperature, at least on the 'heavily used' side of the car - but I'm finding lately that more negative camber is better, and forget the big temp difference. Heat does seem to take a very long time to bleed through the tyres - I wonder whether heat is only transferred between outer tread and inner air, rather than from outer tread to outer tread? Have no real data to base any of those thoughts on.

Yeah I know, we can speculate it is just a graphical/visual feature of the tire deformation, however I do believe it is connected with how the tire is deforming according to the model. If you look at it, the wheel/rim IS actually closer to the ground when this all happens, and that is at least a sign there is heavy loads on the tires, and that there is deformation. Clearly, the forces view shows this too, but either way, the tire should be under extreme deformation, yet it is at its highest peak of possible grip.... If I were to do this with higher tire pressures, there would likely be no visible extreme deformation (good), and it should support the car's wheel under high loads. But when you do this, somehow the grip is lower, and you understeer way too much... and those bars you see would be all red. Dissapointing how sensitive it can be, yet how broad the performance is from using low tire pressures..... VERY low tire pressures should give some grip, but very poor cornering performance under high loads. Medium should be what everyone typically uses, where the car should handle well and have neutral grip. High tire pressures should give the best support and control, and at least still give adequate cornering performance. Very high tire pressures should just be super sensitive and prone to poor tire contact. Right now medium to high is just a useless pressure in LFS in most cases. And even at low speeds it is horrible understeer, which is just so strange, I cannot understand why it is like that.

actually I think there is another inaccurate physics effect at work making high pressures more useful than you say. Posted a thread a while back with little response - http://www.lfsforum.net/showth ... 79&highlight=pressure

the fox likes high pressure on all 4 tyres, the ufr / xfr like it on the rear - will be experimenting a little more with the lx6 this evening, but I doubt it will benefit.

You can adjust the understeer out of a meduim to hich pressure tire though. It takes a completely different approach to setup though and a different driving style i need to go back and build a set around this approach to prove the point and test my theory but will not have a chance until tomarrow.

I find the MRT5 very sensitive to tyre pressure - skips and wobbles with very low pressures, slippy with very high pressures (despite WR sets using max), mid ground makes it handle nicely for me.