Does a GT6/Real World Tire Conversion Chart Exist?

[ALB123]

I don't want this thread to turn into a debate about whether you think the tires in GT6 are too grippy, not grippy enough or if the tires that come on the cars means that's what we should be using. There are plenty of threads for that...

What I am looking for is, with all of the people who play Gran Turismo who feel that the provided "stock" tires are too grippy, has anyone ever made a conversion chart or Microsoft Excel worksheet that lists the car's name in GT6 followed by the type of tire that comes with it and then another column showing what type of GT6 would accurately reflect real-world grip levels?

I hope I'm explaining myself properly. What made me think of this was tonight I pulled my Lamborghini Reventon out of the garage for a few laps around the 'Ring and for some reason I decided to Google search "Lamborghini Reventon" just to see if they got the stock gearing right. Well, they did...but what I also found on THIS webpage was information that the Reventon came with Pirelli P Zero Rosso tires. In Pirelli's own words, the Rosso is a tire that is "The ideal choice for optimum balance between performance and comfort for medium to high-powered cars." Just seeing that word "comfort" led me to believe that the Reventon probably should have CS tires then, no?

Again...I really don't want this thread to turn into a debate about who likes to drive Racing Soft versus who likes Comfort Medium on everything. We have plenty of those threads. I'm looking to see if anyone, who is like me and is looking for the most accurate representation of tire grip level, has already created a document listing what tires they would recommend putting on the GT6 version of a car.

 

[IBZ6L20VT]

I don't want this thread to turn into a debate about whether you think the tires in GT6 are too grippy, not grippy enough or if the tires that come on the cars means that's what we should be using. There are plenty of threads for that...

What I am looking for is, with all of the people who play Gran Turismo who feel that the provided "stock" tires are too grippy, has anyone ever made a conversion chart or Microsoft Excel worksheet that lists the car's name in GT6 followed by the type of tire that comes with it and then another column showing what type of GT6 would accurately reflect real-world grip levels?

I hope I'm explaining myself properly. What made me think of this was tonight I pulled my Lamborghini Reventon out of the garage for a few laps around the 'Ring and for some reason I decided to Google search "Lamborghini Reventon" just to see if they got the stock gearing right. Well, they did...but what I also found on THIS webpage was information that the Reventon came with Pirelli P Zero Rosso tires. In Pirelli's own words, the Rosso is a tire that is "The ideal choice for optimum balance between performance and comfort for medium to high-powered cars." Just seeing that word "comfort" led me to believe that the Reventon probably should have CS tires then, no?

Again...I really don't want this thread to turn into a debate about who likes to drive Racing Soft versus who likes Comfort Medium on everything. We have plenty of those threads. I'm looking to see if anyone, who is like me and is looking for the most accurate representation of tire grip level, has already created a document listing what tires they would recommend putting on the GT6 version of a car.

My personal opinion is that the Reventon must use CS, as you have guessed. Every single road tire must be Comfort. The grippier ones, like PZero Rosso, are CS, while cars from 20/30 years ago, or regular cars must use CM or even CH.

Sport Hard tires must be compared with something like Toyo Proxes R888. A road legal tire but mainly focused in track days use.

SM and SS... I don't think in any possible road legal tire in the market.

The next step are pure slicks for track, and those are Racing tires.

(This is my opinion, and just mine. Everybody else here maybe differ from mine. I just wanted to share my thoughts after a year)

 

[Johnnypenso]

The difficulty lies the way PD alters grip between cars while using a generic tire model. The SH and all its characteristics are the same on a 60's Vette' as they are on that same Reventon what changes is the chassis grip multiplier and other parameters like weight, balance etc. So even though the Vette' would have come from the factory with relatively skinny bias ply tires and the Reventon the aforementioned and much more sophisticated Pirelli's with a different set of attributes. In the game both cars get the same tire, just with the grip podified up or down by the chassis.

Any chart would really be a very rough approximation at best based mainly on lap times and lateral g's but not representative of the overall charactertics of individual car/tire, real life combinations.

 

[Jimmy_Pop]

I agree, after running on Assetto for the week, gt6 tire model is super generic and always pulls a higher later g-force. CS were over 1.1 g's with the Lightning, something that pulled about .9 irl. and the inline grip of a passenger tire in GT6 with any tire it seemed.

 

[l_alcala_d]

The difficulty lies the way PD alters grip between cars while using a generic tire model. The SH and all its characteristics are the same on a 60's Vette' as they are on that same Reventon what changes is the chassis grip multiplier and other parameters like weight, balance etc. So even though the Vette' would have come from the factory with relatively skinny bias ply tires and the Reventon the aforementioned and much more sophisticated Pirelli's with a different set of attributes. In the game both cars get the same tire, just with the grip podified up or down by the chassis.

Any chart would really be a very rough approximation at best based mainly on lap times and lateral g's but not representative of the overall charactertics of individual car/tire, real life combinations.

Thinking about that some time ago. I just concluded that PD just modeled the behavior of the tires in a general way, so instead of creating a model for 60' cars, other for 70' and so on , they just gather data from tires from this age and era, create a tire model based on that parameters and that's all we got (in the name of simplicity I would have take that route), personally I don't have major problems with that approach because I dunno that if you own an original Ford GT 40 road version you could find the same tires with the same manufacturing process (and thus a tire with the same properties as it's 1966) today. Furthermore the way I look at it most of the time I feel that the general cars behaviors aren't altered in big ways, I take for example the RUF Yellowbird in fully stock form (no oil change, no nothing) lots, and I mean lots of people complain about that car, that's modeled in an irreal way because it's to slippery, uncontrollable and unsafe to drive, they forget (I assume they even didn't do a quick search on the web) that's car based over a old school 911 which is car really hard to tame (you must be extremely confident to drive it to the limit); to show them that the car physic model is right you must fire some YouTube video to show how slippery and dangerous is that thing if you got it to the limit.

 

[LancerEvo7]

I agree with what @Johnnypenso said, GT6's tire model will never let you get an exact match. I did make this spreadsheet based on skidpad g-forces, however. I made a few assumptions in places, for example giving 0.05 to Chromelines over the stock car, and I didn't bother with race cars at all.

 

[Jimmy_Pop]

The other issue is on gt6 all the cars feel like you are skating on ice too.

 

[Thematic]

The other issue is on gt6 all the cars feel like you are skating on ice too.

Isn't that a hardware issue though? Your wheel can only give you some "feel".

 

[NCRthree]

The other issue is on gt6 all the cars feel like you are skating on ice too.

Oh for sure but only on the Winter Rally Track

 

[Johnnypenso]

Thinking about that some time ago. I just concluded that PD just modeled the behavior of the tires in a general way, so instead of creating a model for 60' cars, other for 70' and so on , they just gather data from tires from this age and era, create a tire model based on that parameters and that's all we got (in the name of simplicity I would have take that route), personally I don't have major problems with that approach because I dunno that if you own an original Ford GT 40 road version you could find the same tires with the same manufacturing process (and thus a tire with the same properties as it's 1966) today.

That's not how it was done, as I explained above. There is only one tire model, only one SH tire for example, what changes from car to car are weight and weight distribution to get the general feel of the car, and then a grip multiplier is applied to the chassis to simulate the overall grip of the car. But the basic tire charteristics like slip angle, the relationship between latutidinal and longitudinal grip don't change like they would on a tire that was era specific. This is why answering the OP's question will only give rough approximations. Even if you could match lap times exactly it doesn't mean the characteristics of the car are accurate, just that you got to the finish line at the same time.

Isn't that a hardware issue though? Your wheel can only give you some "feel".

Software actually. All depends on the programming and how the designers translate the ingame physics into FFB. That's why iRacing used to be called iceRacing even though it was lauded for it's physics, it didn't provide a really "planted" feel for the car. It's also why the exact same car in one game can feel completely different in another game, with the exact same hardware.

 

[Jimmy_Pop]

Oh for sure but only on the Winter Rally Track

not really, its all tracks, the cars just feel floaty like they are not quite connected to the road, the wheel is fine, works great on everything. But hey, its just an opinion. Some people swear by gt6, I have just fallen out of love with it I guess.

 

[TH4M4DDM4]

That's not how it was done, as I explained above. There is only one tire model, only one SH tire for example, what changes from car to car are weight and weight distribution to get the general feel of the car, and then a grip multiplier is applied to the chassis to simulate the overall grip of the car.

I see each car has 35 tire code strings when calling up "FRONTTIRE" or "REARTIRE", 10 appear to be the visible tire options, & each of the 35 tire's has 3 codes affecting compound grip and 3 force vol codes(structure). Every car has different combinations including variations in tire size. This creates a lot of possibilities for different behaving tires for each and every tire depending on the car its applied to. Im sure inside 1200 cars there are probably a few that may have similar combinations, but I've not found 2 different model cars that have the exact same tires even when the same tire is installed. The only tire codes Ive found when calling up the CHASSIS are wheel/tire position codes that don't affect grip levels.

The coding is not like you say at all. Yes there is the weight balance affecting how cars "feel", but there is a lot more car specific details used to achieve the "feel" of the car. I don't see any of these "grip multiplier codes" applied to the chassis to get the overall grip of the car. They use multiple hidden car specs to achieve the cars "feel" through spring frequency combined with each car getting tires suited to the car. There are no chassis grip multiplier codes being used to get overall grip of any car.

But the basic tire charteristics like slip angle, the relationship between latutidinal and longitudinal grip don't change like they would on a tire that was era specific. This is why answering the OP's question will only give rough approximations. Even if you could match lap times exactly it doesn't mean the characteristics of the car are accurate, just that you got to the finish line at the same time.

I don't think there is are "era" specific tires, but tires adapted to the car they are on regardless of era. I agree that with each car getting slight variations to the listed tires there is no way of forming a list as the OP desires. Slip angles are affected by the camber & toe angle in "SUSPENSION" and the yaw rate in "CHASSIS" and so also will be different from car to car even with the same tires installed.

I agree, after running on Assetto for the week, gt6 tire model is super generic and always pulls a higher later g-force. CS were over 1.1 g's with the Lightning, something that pulled about .9 irl. and the inline grip of a passenger tire in GT6 with any tire it seemed.

When I look at a stock IRL car pull X g at Y speed in a given corner, then the same car at the same spec in the game making the same corner at the same speed but register a higher G, it tells me the cars may be heavier than they should be but not in numerical weight value more along the lines of the force of gravity being too strong. This is interesting because if the force of gravity were too high than the cars would be over weight and too heavy to accelerate to the same top speed. HOWEVER weight changes DO NOT impact top speed to the degree that they should as if the effect of weight on top speed has been greatly reduced near turned off. I think of the KW 7 post rig data being incorporated into GT6 & that data being frequency based. I then look at the "SUSPENSION" coding and see specific codes for frequency and target frequency & realize KW data is the Target frequency. To arrive at the KW target adjustments need to be made to the elements in the equation for our frequency. The best option in my eyes to manipulate the GT physics engine to arrive at a new target frequency is to alter the force of gravity. The actual vehicle weight cannot be altered as its a displayed value while the leverage factor plays into the cars spring rate/wheel rate and overall car feel. With gravity manipulated the top speed has also been freed from its ties to weight somewhat & performance is impacted through acceleration rate. I suspect PD has been working on a way to restore the impact of weight on top speed fully, probably when they get a fix sorted that doesn't throw off everything else we will get it. I suspect we will get back the SSRX Performance Test around the same time. I would never trade the new GT6 Physics Feel for GT5 Top Speeds so in my eyes PD is taking the best possible path.

 

[Griffith500]

I was going to say I'd never seen any grip multipliers in my "travels" either.

The Motec export was made for this thread, I think.
It'd have to be per car to start with.

 

[Johnnypenso]

I see each car has 35 tire code strings when calling up "FRONTTIRE" or "REARTIRE", 10 appear to be the visible tire options, & each of the 35 tire's has 3 codes affecting compound grip and 3 force vol codes(structure). Every car has different combinations including variations in tire size. This creates a lot of possibilities for different behaving tires for each and every tire depending on the car its applied to. Im sure inside 1200 cars there are probably a few that may have similar combinations, but I've not found 2 different model cars that have the exact same tires even when the same tire is installed. The only tire codes Ive found when calling up the CHASSIS are wheel/tire position codes that don't affect grip levels.

The coding is not like you say at all. Yes there is the weight balance affecting how cars "feel", but there is a lot more car specific details used to achieve the "feel" of the car. I don't see any of these "grip multiplier codes" applied to the chassis to get the overall grip of the car. They use multiple hidden car specs to achieve the cars "feel" through spring frequency combined with each car getting tires suited to the car. There are no chassis grip multiplier codes being used to get overall grip of any car.



I don't think there is are "era" specific tires, but tires adapted to the car they are on regardless of era. I agree that with each car getting slight variations to the listed tires there is no way of forming a list as the OP desires. Slip angles are affected by the camber & toe angle in "SUSPENSION" and the yaw rate in "CHASSIS" and so also will be different from car to car even with the same tires installed.

Looks like it's changed from GT5 then thanks for the correction, but if I'm reading you correctly it looks to me like a different path to a similar result. There still is only one basic set of characteristics for each tire compound and the level of grip is modified up and down through tire width and/or the three codes affecting grip. It would also explain why some of the older cars like the Ferraris added to GT6, seems to possess levels of grip equal or almost equal to cars of the current era which logic tells you would never be the case.

 

[TH4M4DDM4]

Looks like it's changed from GT5 then thanks for the correction, but if I'm reading you correctly it looks to me like a different path to a similar result. There still is only one basic set of characteristics for each tire compound and the level of grip is modified up and down through tire width and/or the three codes affecting grip. It would also explain why some of the older cars like the Ferraris added to GT6, seems to possess levels of grip equal or almost equal to cars of the current era which logic tells you would never be the case.

Each of the 35 Tire types (including all compound/type combinations and hidden tires like RB tires, extra soft etc) have 3 codes for grip & 3 codes for the structure specific to each car. Each car has its own combination that is different for all 35 tires and each cars tires have car specific sizes, with 1200 cars, that's 42000 different tires. Since only 10 of the 35 are available normally, that's down to 12000 tires conveniently packaged into a 10 tire selection per car, how much more or less from stock based on starting point (stock tire) its brilliant. Quite possibly Yokohana data is what makes up much of the variations in the compound grip and structure codes and this is how they added in their data to the GT5 set of tires to arrive at the GT6 tires we have now.

 

[Griffith500]

Looks like it's changed from GT5 then thanks for the correction, but if I'm reading you correctly it looks to me like a different path to a similar result. There still is only one basic set of characteristics for each tire compound and the level of grip is modified up and down through tire width and/or the three codes affecting grip. It would also explain why some of the older cars like the Ferraris added to GT6, seems to possess levels of grip equal or almost equal to cars of the current era which logic tells you would never be the case.

Opinion of GT5P was inline with GT6; that the tyres were defined per car - e.g. recall the F2007 on comfort tyres. Either GT5 was an outlier in terms of approach, or the per-car tyre-compound adjustments were intended to provide parity between the tyre choice despite (i.e. to offset) the differences in tyre size and structure from car to car.

As you say, different means to the same end, but substantially different substance and underlying data / systems implied.

 

[Johnnypenso]

Each of the 35 Tire types (including all compound/type combinations and hidden tires like RB tires, extra soft etc) have 3 codes for grip & 3 codes for the structure specific to each car. Each car has its own combination that is different for all 35 tires and each cars tires have car specific sizes, with 1200 cars, that's 42000 different tires. Since only 10 of the 35 are available normally, that's down to 12000 tires conveniently packaged into a 10 tire selection per car, how much more or less from stock based on starting point (stock tire) its brilliant. Quite possibly Yokohana data is what makes up much of the variations in the compound grip and structure codes and this is how they added in their data to the GT5 set of tires to arrive at the GT6 tires we have now.

GT5 also had a massive number of tire types with the C and V rated versions of each compound plus Sport Super Softs, Racing Super Softs etc. Not sure what you mean by "10 of 35 normally available", I only see 9 in the game not 10. What is the "structure code" and what does it do?

 

[Racelouse]

thanks for the insight into whats going on under the hood in GT6 regarding cars and tires.
do you guys also know anything about much of a difference tracks make? i'm sometimes feeling like the same car with the same setup and the same tires feels somewhat different on various tracks.

 

[Harsk100]

And I'm very confused about the tyres of Rally Cars. Do Rally cars use RH tires in real life?

 

[Griffith500]

thanks for the insight into whats going on under the hood in GT6 regarding cars and tires.
do you guys also know anything about much of a difference tracks make? i'm sometimes feeling like the same car with the same setup and the same tires feels somewhat different on various tracks.

This phenomenon used to be discussed to death over in the GPL forums (now srmz) years ago. It was proven that that game had only one grip level for tarmac on any track, but it was clear that some tracks felt grippier than others, or cars felt more stable etc. It was generally agreed upon that it must be track surface camber effects for the most part.

So without knowing how GT defines grip surfaces (I know how it defines sound on surfaces), it'd be worth bearing the above in mind. I think generally, camber in particular is very difficult to see in a game (2D representation), except in the extreme.

 

[TH4M4DDM4]

GT5 also had a massive number of tire types with the C and V rated versions of each compound plus Sport Super Softs, Racing Super Softs etc. Not sure what you mean by "10 of 35 normally available", I only see 9 in the game not 10. What is the "structure code" and what does it do?

9 lol I spend more time looking at the dump from the specdb rather than the in game tire list lol So 9 of the 35 available

They are structure codes that can only make up How much tire flex there is and how the tire reacts to load conditions.

Increases or decreases the tires ability to hold a higher slip angle for example. There is no visible tire flex twist whatever, but clearly as the car are cornering with increased yaw rate and even more so with adjusted toe angles the tires are griping on a slip angle. This is affected not only by the compounds grip levels, but also the tires structure and so ability to flex.

 

[LancerEvo7]

And I'm very confused about the tyres of Rally Cars. Do Rally cars use RH tires in real life?

There's no good way to determine it, but I'd assume they run something similar to Sports tires on tarmac in real life.

 

[TH4M4DDM4]

This phenomenon used to be discussed to death over in the GPL forums (now srmz) years ago. It was proven that that game had only one grip level for tarmac on any track, but it was clear that some tracks felt grippier than others, or cars felt more stable etc. It was generally agreed upon that it must be track surface camber effects for the most part.

So without knowing how GT defines grip surfaces (I know how it defines sound on surfaces), it'd be worth bearing the above in mind. I think generally, camber in particular is very difficult to see in a game (2D representation), except in the extreme.

They use track temperature to alter track grip from track to track on top of the track surface type, although I do not have any codes on track surface type I suspect thats in the track data, I do have the specdb dump for multiple tracks with the temp data, elevation, there is even the option for wind although Ive not seen a track with a value for it other than zero.

 

[Griffith500]

They use track temperature to alter track grip from track to track on top of the track surface type, although I do not have any codes on track surface type I suspect thats in the track data, I do have the specdb dump for multiple tracks with the temp data, elevation, there is even the option for wind although Ive not seen a track with a value for it other than zero.

I forgot about track temperature, which was also in GT5. And I seem to remember that wind was random in GT5, but it's not (visually) present in GT6, despite references for the particles etc.

@Racelouse I guess the idea would be to see how the perception of grip tallies with the default track temperature.

 

[super_gt]

Live For Speed is more than ten years old game and has better tire simulation than GT6

 

[TH4M4DDM4]

I forgot about track temperature, which was also in GT5. And I seem to remember that wind was random in GT5, but it's not (visually) present in GT6, despite references for the particles etc.

Track Temp is big on grip. I have a Nova Dragger that wheelies off the line, BUT Only at High noon in the sun. In the tunnel,not enough grip, in the night not enough grip, but out in the sun, she loves to stare up at the sun.

Im concerned about wind for things like top speeds, since Ive had reduced top speeds at LaSarthe, Ill have a closer look into that track

 

[Johnnypenso]

Track Temp is big on grip. I have a Nova Dragger that wheelies off the line, BUT Only at High noon in the sun. In the tunnel,not enough grip, in the night not enough grip, but out in the sun, she loves to stare up at the sun.

Im concerned about wind for things like top speeds, since Ive had reduced top speeds at LaSarthe, Ill have a closer look into that track

Can you post your setup so we can test that? It's been a big debate around here before and I don't think there was any definite conclusion.

 

[TH4M4DDM4]

Can you post your setup so we can test that? It's been a big debate around here before and I don't think there was any definite conclusion.

She has 405's

Quite honestly its obvious and so clear so its not even theory or suspicion, its a fact. I question anybodies ability to detect grip differences if they cant detect the obvious grip differences due to track temp. If the hound cant smell a Duck I don't have a use for him on a hunt.

 

[Johnnypenso]

She has 405's

Quite honestly its obvious and so clear so its not even theory or suspicion, its a fact. I question anybodies ability to detect grip differences if they cant detect the obvious grip differences due to track temp. If the hound cant smell a Duck I don't have a use for him on a hunt.

Oops...banned already..

 

[lGNAl]

The main issue with tire/surface modeling is the floaty ghost-like movement of the car, with the handbrake pulled, in some uphill/downhill area's of some track's. Off the top of my head Sarthe (just as you're going downhill after Dunlop).
If someone has experienced this before, please post a video. When that gets fixed, then we can talk about other tire physic's/modeling problem's.