GT5 Tire Model

I have forgotten what was the OP about, but anyway, try to experiment with tires and you definitely find a right ones.

TomBrady: I got some irl track time, and in a lot of cars that we can drive in GT5. When it comes to "how it feels" when comparing GT5 to real life, I can honestly say that I can't for my life feel the car in the same way I do irl. It's impossible to compare. irl, you're so much more "one with the car" sort of.. Every millimeter feels thru the seats, and you can adjust accordingly.
In GT5, those millimeters are'nt noticable.. The lack of G-forces and such are also a major obsticle when it comes to comparing real life and GT5 with how it feels.

I owned a E46 M3 Comp. Package '05 for 2 years that I drove a lot on different tracks. I can recognize/relate some behaviours, but even though I owned the car for 2 years, I still can't say that I feel the M3 '04 in game even close to how I felt my own M3 irl..

Regarding the tyre model: To me, I don't care what compuond I use.. Be it CH or RS.. As long as the car grips as irl (comparing real life lateral G's and translate that to the tyre needed in GT5 to replicate that in the best way), I'm happy.. So the Enzo grip 1.10 irl, and the Enzo grip 1.10 in GT5 with Sport Mediums.. Sport Mediums it is.
That's the only way to get even close. Cause i.e Comfort Softs are'nt one specific tyre in GT5, Comfort Softs represent a sertain level ov Lateral grip, and that's a huge difference.
There's no way we can say: "Those cars go with CS, those with CM, those with SH's" etc. That's not how our "grip multilyer" is designed. It's all about comparing the real life lateral grip, and from that, equip the car with what replicates that as close as possible. 👍

As an example: If the Mini '02 and ZR1 was equiped with the same tyre IRL (i.e Michelin Pilot Sport II), the latteral grip for the ZR1 would still be much higher compared to the Mini '02. But in GT5, both cars have the same lateral grip if fitted with the same tyre, hence why I don't see the tyres as 1 specific type of tyre, but more as a grip multiplyer.

TomBrady

I think it's funny that people are bashing the tire model. What's especially strange is people saying that they have the progression from grip to no grip all wrong. Quite the contrary. That's one of the few things they do very well. The progression is one of the best things about GT5, because it's more spot on than even some PC sims. The only sims that do the progression from grip to no grip better than GT5 is LFS and netKar Pro. That's it. Now I'm not saying GT5 is on par with those 2 overall, but it doesn't really have to be because the progression is done so well. To me that progression is very important in making a sim enjoyable or not. I love iracing but for me the one reason why it will never top netkar pro (realism wise) is the progression from full grip to none is just far too steep of a curve. Has anyone wondered why you don't see people making drift videos in iracing? Well there you go. Rfactor & GTR 2 as well. The drop off is far too rapid and very unnatural. Drifting in GT5 is natural. That's what's so great about the tire model. It doesn't need built in aids to help the physics feel natural *cough* forza *cough*. It seems apparent to me you guys have lots of knowledge of how sims model the tires, but I question how you really can compare it to real life because no amount of knowledge on paper can match on track experience. For the most part, GT5 does a superb job replicating the feel of the cars it models, even with it's shortcomings. I know that from experience on real tracks. They may not get the job done in the best way, but they do get it done and it's certainly a huge step forward compared to past GT's, and other console arcade sims. Fact is, the room for improvement you all have pointed out only goes to show how much better things can get if they decide to go in the right direction with GT6

Of course I would agree in some ways the tires are terrible, racing softs are just unusable in my opinion but overall, the physics are great for the console. Keep in mind that most of the people who play GT5 use controllers. Compromises obviously had to be made. Considering that, they did a great job

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I've more than enough real world track, fast road, proving ground and test track time to know that GT5's tyre model doesn't have even close to the degree of progression that it should have. This is particularly true when it comes to the limits of slip and self aligning torque starts to reduce.





The lack of any form of contact patch and sidewall deformation takes care of that, and the issue with width and profile not being correctly accounted for the model means that RR cars behave in a manner than doesn't come close to correct.

Scaff

I've more than enough real world track, fast road, proving ground and test track time to know that GT5's tyre model doesn't have even close to the degree of progression that it should have. This is particularly true when it comes to the limits of slip and self aligning torque starts to reduce.

The lack of any form of contact patch and sidewall deformation takes care of that, and the issue with width and profile not being correctly accounted for the model means that RR cars behave in a manner than doesn't come close to correct.

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[Bould]: Can't one big reason for that be that you can't "feel" the car in the same way on a screen compared to real life?
I mean, the slip might be there (programmed in GT5), but since we can't feel the slip thru the screen (contrary to what would be the case irl), we say that the limit is too steep/we experiance less progression?

Oh, and would you mind trying to explain more in detail how to read the diagram you posted? It looks really interesting, but I have some trouble reading it properly I think. Thanks.

I'm with Denilson, Scaff. Could you please explain that diagram in laymans terms?

Denilson

[Bould]: Can't one big reason for that be that you can't "feel" the car in the same way on a screen compared to real life?
I mean, the slip might be there (programmed in GT5), but since we can't feel the slip thru the screen (contrary to what would be the case irl), we say that the limit is too steep/we experiance less progression?

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Other sims (both on console and PC) manage to communicate this to a reasonable degree, it does require more than just the use of FFB, as audio (tyre noise) and visual (visible body control and suspension) cues are critical.

Its not just that I have never felt/heard/seen this in GT5 across a range of pads/wheels, but that GT5 doesn't even vary it between tyre types. The lack of progression (as I hope will become clear by the end of my post) on road tyres is just all wrong, even at low speeds the progression is none existent. A light RWD car on skinny road tyres should be a learning tool in easy low speed power oversteer (as they are in the real world), in GT5 they just go grip......no grip. An original MX-5 on OEM tyres is a joy to drive with a frankly daft level of progression and communication, GT5 captures none of that via the tyres.

Denilson

Oh, and would you mind trying to explain more in detail how to read the diagram you posted? It looks really interesting, but I have some trouble reading it properly I think. Thanks.

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No problem.

The first basic bit you need to understand is that tyres, being made of rubber (and other stuff) deform as load is placed on them. This includes twisting force, so as you turn a tyre the contact patch distorts and twists, this causes an increase in tractive forces (grip) between the tyre and the surface its on, and this resistance can be felt via the steering (Self Aligning Torque).

You can try this for yourself by getting an eraser, placing it flat on a desk and then with your hand on top of it applying pressure (downwards) and twisting. You can feel the eraser changes shape and the grip increase. However once you get to a certain point (around the grip limit) the contact patch slips too much and returns to shape, with tractive forces and Self Aligning Torque reducing.

However a 'magic' little zone exists just as the contact patch deformation starts to reduce and the Self Aligning Torque drops off when you have the most tractive force available. This is when the most grip can be obtained from the tyre.

So how does this translate into the graph, well the information shown is as follows:

• Self Aligning Torque - Measured in NM the torque generated by the tyre as its contact patch deforms - felt through the steering as an increase in resistance.
• Lateral Force - Measured in kgs, the cornering force generated by the tyre
• Slip Percentage (not named) - the variation between the direction the vehicle is travelling in and the tyre is traveling in. Measured as a percentage difference, as this increases so does lateral force, up to a point (dependant on the tyre) beyond which lateral force drops off.

So as the car starts to turn the slip rate of the tyre will increase, lateral force will increase and SAT (Self Aligning Torque) will increase, so we feel the 'grip' from the tyre (lateral force) as resistance through the steering (SAT). These increase in relation to each other up to (for this tyre) approx 3degrees of slip, at which point we have 650kgs of lateral force and 100nm of SAT. The steering feels 'weighty' and we have a good amount of grip.

Continue to push the tyres however and something different happens (that 'magic' zone), while the lateral force continues to increae (but at a much smaller level) the SAT drops off, with the steering suddenly feeling light. With the numbers looking like this:

• 3 degrees slip - 650kgs lat force / 100nm SAT
• 4 degrees slip - 740kgs lat force / 82nm SAT
• 5 degree slip - 775kgs lat force / 50nm SAT
• 6 degrees slip - 780kgs lat force / 20 NM SAT

Once we get beyond 6degrees of slip with this tyre lateral force starts to reduce. However between 3 and 6 degrees of slip we can see that we can gain an extra 130kgs of lateral force, quite a difference. However the steering gets rapidly lighter, with less resistance as it does, dropping to 20% of the SAT we had at 3 degrees of slip.

It takes a lot of experience, skill and feel to extract this last part of a tyres grip, as most people (hence the broad groups you see on the graph) back off as soon as the steering resistance reduces because they equate grip with resistance. Its still possible to feel what is going on past this point, but care is needed to ensure that you don't overcorrect (as the resistance reduces) or miss-judge the reduced increase inn grip.

Now six degrees of slip as a limit is at the performance end of things and road tyres would be closer to 4 degrees as a limit, however unlike slicks or semis, the large tread blocks move more and the increase in SAT can be much more gradual and the fall off a little less extreme (please note the this is a genarallisation and not a rule - cheap/old tyres can rise and drop in a very nasty manner)

GT5 doesn't do this well at all, the lack of contact patch deformation and the issue with primary ride/low speed damping feedback being feed via the FFB (which does not happen in a real car at all - this is felt via the body not the steering) cause this. GT5 pretty much gives you grip up to point 'X' in terms of lateral force and then beyond that grip just drops. Nor does GT5 account for the differences in these models between Road, Semi and Slick tyres.

Its interesting that LFS was mentioned earlier, as the makes fully acknowledge that one of the weak areas they still have is in regard to the tyre model, particularly deformation.

http://www.lfs.net/

LFS does a lot very, very well (suspension modeling for the limited range they have is excellent), but the current tyre model is not one of them. Its better that GT5's but still has a way to go.

Noise can be made about FM4 for a number of things, but the tyre model (while still incomplete) is streets ahead of GT5's, in that it at the very least covers deformation across two axis and pressure/temp interaction. As a result it offers a more natural path along the graph above and more natural feeling and reacting tyres.

This example I believe helps to illustrate what I mean, watch it slowed down after the spin to see the tyre deformation.



Even Enthusia (despite its many issues) had a better suspension and tyre model than GT5 does (and both FM4 and GT5 could both learn a lot from parts of Enthusia).



Anyway I hope that the above helps explain the graph and as a result what I see as the issues with GT5's tyre model.


Regards

Scaff

So, what do we finally define? As conclusion...
Do we have to wait when PD make a better tire model?
Can PD suggest us required tires for any single care based on their knowledges?
Or, we continue our research on tires and make Master List of tires proved to be close to reality?

Yes.
PD need to improve their model and FFB.
They need to suggest appropriate in-game tyres (or put the right ones on stock).
We should continue to investigate its accuracy and report our findings.


Great post, Scaff. 👍
I do wonder how much of the required feel is "eroded" by slightly quirky FFB. It's interesting for me that I'd never noticed the lack of (consistent?) lightened steering near the limit in GT5 (although now it's plain as day in my recollection, without having to touch the game), yet it's something I tend to rely on heavily in sims, especially the Kaemmer catalogue.

Maybe GT does its "convincing" or "communication" in a different way, or I have alien skills I never knew about? (I highly doubt it's the latter!)

The low speed physics and general car (multi-, rigid-body) and suspension kinematics are really screwy, though. Then again, they improved the suspension model with an update, so they know it's a weak point - don't they have a specialist now? There were rumours it was the same guy(s) from Enthusia, but he's (they're) not credited.

Scaff: Thank you for the explenation.
So to confirm I got it right, the graph show where in the SAT spectra different skilled drivers can balance the grip.
An average driver stop pushing as soon as the "weighty" feeling drops off.
A skilled driver can push it a tad further, but stop pushing as the SAT start to go down more rapidly.
A race driver can push the tyres all over the SAT spectra. All the way, and just before the SAT is none and the tyre loose it's grip.

Thanks. 👍

There's the caveat that in real life, street tires (or worse: worn, hardened cheap tires) won't be able to generate a slip angle as high as semi-slick or slick tires can.

Denilson

Scaff: Thank you for the explenation.

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+1,
Give me more! Love the info you feed us.

Ridox2JZGTE

^ I agree with that, I always have comfort hard/medium tires available for use on every street car up to 600pp



I did the same a while ago, Ferrari 458, stock, no tuning, Monza, rain 100% weather, all assist off, comfort medium, BB 7/5, got a lap time of 2:07.xxx

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OOOOOO, you must be GENIUS!
On Comfort Medium Tires with 100% water on track you did 2.07.xx?????????
I definitely want to learn driving from you.
If someone here could try to do something near his result I would appreciate it.
This dude must be kidding us.

Olegonic

OOOOOO, you must be GENIUS!
On Comfort Medium Tires with 100% water on track you did 2.07.xx?????????
I definitely want to learn driving from you.
If someone here could try to do something near his result I would appreciate it.
This dude must be kidding us.

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I posted this in another thread :

https://www.gtplanet.net/forum/showthread.php?p=7192440#post7192440

But, for your convenience : ( sorry if the quality is not good )



Go to the Youtube page for full description. ( 100% weather, 0-10% water on track during the run )
You must have misunderstood me, I wrote 100% weather - as in track setting, I did not wrote about the % of water on track. Even if I set 100% weather, the rain will start at the beginning of the free run as I did set 0% surface water at the start, thus track has 0% water on surface and will increase rapidly as the rain gets heavier with 100% weather.

In GT5 Comfort tires perform better than Sports tires in wet conditions.

Much like in real life, semi slicks won't do as good as fully treaded all season hi performance street tires on the wet road.

Ridox2JZGTE
My bad, I did actually misunderstand you about water on track. Sorry.
So, what tires do you think we should equip 458 with?

Olegonic

Ridox2JZGTE
My bad, I did actually misunderstand you about water on track. Sorry.
So, what tires do you think we should equip 458 with?

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No problem, mate. All is good

For Ferrari 458, I usually fit comfort medium tires for both online and offline cruising - no races. Sometimes, I do fit comfort soft on 458, and most very high powered cars above 400hp - mainly for races, while comfort hard is reserved for cars with 250hp and below.

SHIRAKAWA Akira

In GT5 Comfort tires perform better than Sports tires in wet conditions.

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Yes, but I think that only applies if grip reduction is set to "real".

Skid Recovery Force has an effect on that too, I think.

SHIRAKAWA Akira

Skid Recovery Force has an effect on that too, I think.

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I didn't know that. In fact, I have no idea how SRF actually works!

I run stock Honda NSX 2002 on Tsukuba. No oil change and engine brake in. All assists OFF. BB 2-1. Arcade mode time trial.
Comfort Medium tires. Time 1:06.9. I can shave .5 sec off I think. (283 bhp, 1270 kg)
Real life Honda NSX 1995 time on Tsukuba is 1:06.01 (270 bhp, 1281kg)
BUT, I didn't took into consideration the weight of a driver.
I will add 65 kg of ballast and make more tests. Post later.

Olegonic

I run stock Honda NSX 2002 on Tsukuba. No oil change and engine brake in. All assists OFF. BB 2-1. Arcade mode time trial.
Comfort Medium tires. Time 1:06.9. I can shave .5 sec off I think. (283 bhp, 1270 kg)
Real life Honda NSX 1995 time on Tsukuba is 1:06.01 (270 bhp, 1281kg)
BUT, I didn't took into consideration the weight of a driver.
I will add 65 kg of ballast and make more tests. Post later.

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You might want to increase the BB to 5/0, BB numbers in GT5 also affect brake strength, with 5/0 - the red brake bar can be filled up to 70% before locking up, with higher BB numbers, the car can brake harder and deeper at the expense of lower lock up threshold - at 9/7 filling up 50% brake bar will lock up at low speed.

To understand what I mean, do this with the NSX, put comfort hard all around, set the BB via RA menu to 10/0, hold the brakes - 70% pressure, full throttle, let go of the brake and reapply again immediately at 70% - do not apply full pressure. The NSX should do a burnout, open up RA menu, then increase rear brake one by one, after 3 or so the rear tires will be overpowered by the brake and stops. This cannot be done with ABS enabled.

By the way, interesting test with the added ballast to replace driver's weight, I've done that too, trying to simulate real life car weight when driven. Most sims won't even take that into account.

+65 kg ballast ( 1335 kg total), restrict engine power to 270 bhp. All assists off, ABS OFF.
Time 1:06.924
So, may be Comfort Medium are proper tires for NSX 2002?

Which NSX 2002 do you use for the test ? Type R or base model NSX ? I found this :

http://www.fastestlaps.com/cars/honda_nsx_32.html

1997 NSX - 1388kg, 276hp Tsukuba lap time 1:08.71

You should also do more tests with similar powered cars like Rx7, R34 GTR, R33 GTR, Lancer EVOs. If the majority of the cars of the same PP ( 450 - 520pp ) in GT5 with CM tires could post very close to the real life record, then it will be more convincing than just one car.
This is a good reference :
http://www.fastestlaps.com/tracks/tsukuba.html

EDIT : Ruf CTR Yellow Bird real life Tsukuba lap time : 1:06.12, this is a great example for GT5 - run the Ruf with CM, I wonder if it will get close time ?

I use NSX R 2002.
Lap time was taken here on 1995 NSX R

Great post, Scaff. I had no idea tires still have more grip to give after the steering goes light, I always thought that meant I over-did it. That would take a lot of experience to find that "sweet spot"!

Ridox2JZGTE

EDIT : Ruf CTR Yellow Bird real life Tsukuba lap time : 1:06.12, this is a great example for GT5 - run the Ruf with CM, I wonder if it will get close time ?

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About the yellow bird, what tyre would match the real yellow bird and how to take into account that the real life rear tyres are twice the width of the front?

leeson65

Great post, Scaff. I had no idea tires still have more grip to give after the steering goes light, I always thought that meant I over-did it. That would take a lot of experience to find that "sweet spot"!

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Grip at "peak grip zone" is quite flat on tires respect to angle of attack.This means that when you are driving on the limit, your inputs have less impact what car is doing compared to when you are under the limit or over it. In other terms, you can saw the wheel more when you are on the limit and not have major implications on your laptime. Knowing the limit is of course other thing

I've always used the following as a rough guide, it works for me. It only applies to cars that haven't been tuned, & that are being driven on dry tracks though.




Source.


👍

VBR

I've always used the following as a rough guide, it works for me. It only applies to cars that haven't been tuned, & that are being driven on dry tracks though.

Source.


👍

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Thanks VBR, this is very good, are you aware of a list with real life skid pad value some where in GT Planet or else where?

Found a Skid Pad value for the Y Bird at .90g in http://www.exoticcarsite.com/pages/tuners/ruf_ctr_yellowbird.htm