GT4 vs REAL - An investigation of times

[Scaff]

Not sure what kind of cars you find in the C-segment, Scaff?? It's more designers who wants wider tires, because of better looks.

C Segement would generally include cars of a Ford Focus, VW Golf, Renault Megane size.

However the whole segment structure has become more and more blurred over the last 5 or so years.

On the other hand, for GT4, it's a bit of a mute point. On the other, other hand perhaps we don't want a game where you have to be a tyre expert, suspension expert etc. ?

Speak for yourself, personally I don't think GT4 goes far enough in tuning by a long shot, but thats just me.


Regards

Scaff

 

[Mad Matt]

To expand on the theme, I agree to a point. I would like the possibility, but not the necessity, if you see what I mean?

 

[niky]

C Segement would generally include cars of a Ford Focus, VW Golf, Renault Megane size.

However the whole segment structure has become more and more blurred over the last 5 or so years.

Not to mention the fact that the cars are probably a whole lot larger now than they were when the book was written. Standard "comfort" sizing now is usually 185-195, while I'm seeing "sporty" cars shod in 205s and above.

Besides caster tuning and dynamic camber, it would be really swell if GT4 modeled dynamic wheel weights, sizes and tire profiles.

 

[Wolfe]

There are all sorts of "it would be swell if" things when it comes to driving simulator physics engines, and many of them are somewhat impractical...

From the looks of it, ScaViEr plan on including most of the more prominent ones in Live for Speed. I just hope that GT5/Forza2/EPR2/TRD4 make an effort to catch up with the British trio...

 

[Scaff]

Not to mention the fact that the cars are probably a whole lot larger now than they were when the book was written. Standard "comfort" sizing now is usually 185-195, while I'm seeing "sporty" cars shod in 205s and above.

They are indeed, take my Celica as an example, that runs on 205.

Also all of the above needs to be considered to relate principally to road cars, where comfort, self centering, etc are very important. The second you get to dedicated track cars that have very different priorities and suspension set-up (particularly in terms of camber) things start to get a lot more involved.

Besides caster tuning and dynamic camber, it would be really swell if GT4 modeled dynamic wheel weights, sizes and tire profiles.

There are all sorts of "it would be swell if" things when it comes to driving simulator physics engines, and many of them are somewhat impractical...

From the looks of it, ScaViEr plan on including most of the more prominent ones in Live for Speed. I just hope that GT5/Forza2/EPR2/TRD4 make an effort to catch up with the British trio...

It would indeed be good, to me caster and tyre pressure settings should always have been in the GT series, they are fundimental. The more you look into the physics and dynamics involved in simply driving a car around the more you have to admire anyone who sits down to design a racing or driving sim, the work involved is simply huge. Particularly as using real world data for analysis is so difficult due to the constantly changing valriables at a track.

Hats off to them all.

Regards

Scaff

 

[LeadSlead#2]

Go SCAFF! that was an awesome post.

I've had my "eureka" moment.
That said, this means there is an absolute "perfect" tire size for every car in the world. Dry, Wet, and Snow.
Car manufactures never put big enough tire on stock cars to maximize grip. If I had to guess, I'd say passanger cars have tires a great size for snow, and sports cars usually get set for rain. Possibly none get it for dry.
I know putting wider tires on my cars will increase dry and wet grip. I also know the wet grip increased will be less than the dry grip. My car grips like a tank in snow.
There MUST be a mathmatical equation for the "perfect" tire size for any car. weight dist. weight at each wheel, and drivetrain will find them. (weight transfer)
Anybody know what it is?
If only PD figured this out and factored it in. with avail. diff sizes, so you can make them too wide.

 

[amp88]

Lets be honest GT4 (and a lot of others) are hardly great in the area of tyres, for example the best tyre to use at Tsukuba wet are the R5's, which is a very soft slick tyre. Driving a full race slick (soft or otherwise) on a wet surface is akin to driving on ice, yet in GT4 they offer amazing levels of grip.

Well, the R tyres are shown in GT4 as slicks, but they're really "racing tyres". In real life racing series, when it starts raining they put on treaded "racing tyres" (as I'm sure you're no doubt aware). They don't stick treaded road tyres on. I think it's safe to assume when you put racing tyres on your car on a wet track they're treaded, not slick.

 

[Wolfe]

Well, the R tyres are shown in GT4 as slicks, but they're really "racing tyres". In real life racing series, when it starts raining they put on treaded "racing tyres" (as I'm sure you're no doubt aware). They don't stick treaded road tyres on. I think it's safe to assume when you put racing tyres on your car on a wet track they're treaded, not slick.

The general consensus is that treaded track tires are S tires in GT4. R tires are slicks.

 

[amp88]

The general consensus is that treaded track tires are S tires in GT4. R tires are slicks.

I don't think you follow me. The R tyres in GT4 are racing tyres, the description for them is slick and they look slick in pictures. However, in real life when it rains the teams put on treaded racing tyres. The tyres are still racing tyres, but they have tread to clear the standing water. As I said before, I think it's safe to assume this is the case in GT4 aswell. Take a look at this to see what I mean. The image about halfway down the page has various F1 tyres on it. They're all racing tyres, but some are treaded and some are slick (for wet and dry conditions respectively).

 

[Scaff]

Go SCAFF! that was an awesome post.

I've had my "eureka" moment.
That said, this means there is an absolute "perfect" tire size for every car in the world. Dry, Wet, and Snow.
Car manufactures never put big enough tire on stock cars to maximize grip. If I had to guess, I'd say passanger cars have tires a great size for snow, and sports cars usually get set for rain. Possibly none get it for dry.
I know putting wider tires on my cars will increase dry and wet grip. I also know the wet grip increased will be less than the dry grip. My car grips like a tank in snow.
There MUST be a mathmatical equation for the "perfect" tire size for any car. weight dist. weight at each wheel, and drivetrain will find them. (weight transfer)
Anybody know what it is?
If only PD figured this out and factored it in. with avail. diff sizes, so you can make them too wide.

Glad to help and thanks for the praise.

In regard to the theoreticaly 'perfect' model then yes in theory it is possiable, however the problem with it comes in the sheer variance in load transfer possabilities that come with everyday driving. Just think about the differences between how a car reacts when you brake normally when coming to rest at a stop sign, compared to how it reacts when you have to do an emergancy stop when a dog runs out in front of you (as happened to me last night).

Its a hugely complex area, which is why I find it so much fun.

Well, the R tyres are shown in GT4 as slicks, but they're really "racing tyres". In real life racing series, when it starts raining they put on treaded "racing tyres" (as I'm sure you're no doubt aware). They don't stick treaded road tyres on. I think it's safe to assume when you put racing tyres on your car on a wet track they're treaded, not slick.

Got what you were saying now, my bad, being to literal with the tyre decriptions in GT4.

Regards

Scaff

 

[Mad Matt]

Something else which doesn't seem to be modelled in GT4 is surfaces and variation in surfaces, look at the US GP last year!

This also impacts on the perfect tyre concept.

 

[LeadSlead#2]

well I'm positive there is a "perfect" tire size for each car.
One could get a generalized number based solely on weight, and weight dist f/r and l/r, and hp, drivetrain. just for the general weight transfer amounts these tires will encounter.<---and center of gravity.(if more precision is desired
Obviously, depending on you chassis flex, and suspension stiffnes, and shock resistance, this will change a slight amount, but I'd never expect a game to include all that.
However, if somebody could figure out the "simple" equation, that could be entered into a game.

 

[amp88]

Got what you were saying now, my bad, being to literal with the tyre decriptions in GT4.

Regards

Scaff

I re-read my first post and it wasn't very clear. I was struggling a bit to say what I meant. Here are a couple of pics confirming my assumption. On the left is the FGT at Tsukua Dry and the right is the FGT at Tsukuba Wet. As you can see, there's definitely a difference in the tyres.

 

[Scaff]

Something else which doesn't seem to be modelled in GT4 is surfaces and variation in surfaces, look at the US GP last year!

This also impacts on the perfect tyre concept.

That does depend on what exactly you are talking about, because GT4 certainly does model surface changes and they do have an effect on car set-up. Tracks such as Le Mans, Nurburgring, Deep Forest, etc; all have surface changes, bumps and irregularities that have an effect on how you set-up a car.

If you are talking about the abrasive nature of different surface and the effect they have on tyre wear then certainly that does not seem to be modelled.

I re-read my first post and it wasn't very clear. I was struggling a bit to say what I meant. Here are a couple of pics confirming my assumption. On the left is the FGT at Tsukua Dry and the right is the FGT at Tsukuba Wet. As you can see, there's definitely a difference in the tyres.

Never noticed that before, will have to have a look tonight.

👍

Scaff

 

[Mad Matt]

Yes, I mean the abrasion (hence the US GP comment), but also the chemical reaction between the surface and the tyre.

Come to think of it, there's also the laying down of rubber, and rubber marbles, which seems to be modelled in GTR.
.

 

[LeadSlead#2]

SCAFF - what about tires built with extremely stiff sidewalls?
Example: 245/40/17 vs. 275/40/17 - with extremely hard sidewalls, 44psi standard, how is this tire going to "squish" down and get an equal portion of rubber constantly on the pavement?

 

[Scaff]

SCAFF - what about tires built with extremely stiff sidewalls?
Example: 245/40/17 vs. 275/40/17 - with extremely hard sidewalls, 44psi standard, how is this tire going to "squish" down and get an equal portion of rubber constantly on the pavement?

Thats the point at which things start to get very complicated, the link I provided above does give some basic information on sidewall flex, but its limited.

You are correct that sidewall stiffness can and will have an effect on this (the contact patch not changing when tyre sizes change is a great example of "all other things being equal") and it can have an effect on the contact patch size and or shape.

Sidewall flex itself is can be a compromise as well, lower profile generally gives less flex and therefore less contact patch deformation under lateral loads, however it will then reduce the tyres ability to act as a part of the suspension system. For road cars this results in an increase in road noise and a reduction in ride comfort. Normally this are not areas of concern for most race cars, Formula One being the exception, ever wondered why F1 cars have tyres with such high sidewalls?


In simple terms its because they run the cars with almost solid suspension systems in place, and the tyres sidewall are engineered to act as the primary suspension systems. It mainly came about as a way around the introduction of the plank (wooden plank all F1 cars have underneath to stop the cars running too low ride heights), conventional suspension movements would have run the risk of wearing the plank, so they went for almost fixed suspension systems and let the tyres do the work. Its why F1 is so tyre sensitive; the trend has reversed a little in the last decade as suspension technology has advanced, but the set-ups are still stupidly stiff.

Just to show you we are not alone is discussing this subject, have a look at the following link, its from an engineering forum I browse from time to time.

http://www.eng-tips.com/viewthread.cfm?qid=102250&page=1

Regards

Scaff

 

[Mad Matt]

Tyres are part of the suspension on all cars, look at the way the new 3 series BMW now runs well on the run flat tyres. I think you may be overstating the case for F1.

If you look at the reviews for a track like Spa you always see them talking about suspension set-up for Eau Rouge as the car tends to bottom out before the start of the hill. This is dealt with by a suspension adjustment, not a tyre change.

You also see them adjust the suspension for tracks where they want to ride the curbs a lot.

On the other hand the F1 teams have been in trouble with the tyre companies for trying to run the tyres with too little pressure and it's not uncommon to see the drivers change tyre pressures during a race.

 

[Mad Matt]

Forgot to mention, interesting link to the engineering site! I also noticed that the guy on the Tyre Bible site references Subaru, which is ironic given the problems they've had with tyres the last two seasons and shows how complicated it all is.

 

[Scaff]

Tyres are part of the suspension on all cars, look at the way the new 3 series BMW now runs well on the run flat tyres. I think you may be overstating the case for F1.

If you look at the reviews for a track like Spa you always see them talking about suspension set-up for Eau Rouge as the car tends to bottom out before the start of the hill. This is dealt with by a suspension adjustment, not a tyre change.

You also see them adjust the suspension for tracks where they want to ride the curbs a lot.

On the other hand the F1 teams have been in trouble with the tyre companies for trying to run the tyres with too little pressure and it's not uncommon to see the drivers change tyre pressures during a race.

I can assure you I'm not overstating the case for F1, you can find conformation of this from many sources, but the best one is

Race and Rally Car Source Book

Changes of the nature you have mentioned are commonly dealt with by a change in the Ride Height of the car, but tha vast majority of the suspension work in a modern (by that read last decade or so) F1 car is done by the tyres, particularly for the front end.

As I said above this has reduced slightly over recent years, but have a close look at the front end suspension of an F1 car, you will be very hard pushed to notice any movement at all.

Remember I did not say that the suspension was fixed solid, but that the majoriy of the workload is now commonly done by the tyres.

Its also a mistake to not think that specific tyres are not used for specific circuits, not just for the reasons outlined above, but also for the differing grades of tarmac, ambient temps, etc.

Forgot to mention, interesting link to the engineering site! I also noticed that the guy on the Tyre Bible site references Subaru, which is ironic given the problems they've had with tyres the last two seasons and shows how complicated it all is.

Quite right, and it does help illustrate what a complex subject it is.

BTW - dkid you know that rather than posting twice in a row, you can edit your original post to add information, just click on the edit button at the bottom right of the post.

Regards

Scaff

 

[LeadSlead#2]

So, we've spoken about cars running times that are just too fast in GT4.
But what about the cars that can't keep up? A perfect example is the Nissan Skyline, which, the R33 broke the 8 minute barrier. then, the R34 held the record for a time, besting the Porsche 996. yet, these cars cannot run any faster than an 8:04, as far as I've seen anyone do. and again, with RUF's, would a 512hp CTR2 ONLY run in the 7:50's? (or high40's I forget) everything I'm told is that Porsche's run fantasically on the 'Ring, yet most all RUF's are difficult to drive on it, and usually have sluggish lap times.

and on a completley different note, what about FF's? sure, some can run quite fast times, but you can't run any race against RWD or even 4WD cars, without pitting twice as much, even if you're power is much lower, what gives? and how did they get "physics" to determine no FF car can run a 14-second 1/4? even the very fast ones can't reach 60 in less than 7.5-8 seconds, yet IRL, the new Civic, GTI, & Cobalt SS ALL run around 6.3, with the SRT-4 claimed in the 5's bracket.

I guess just don't put too much weight behind GT4 compared to real-life, otherwise, you'll think Ford GT's are faster than Saleen S7's, despite the aerodynamics of a brick-wall. (Viper-matching 0.39 cd)