Tire Testing - Strange, but interesting results...

[vkhibkin]

I think the fact that GT5 doesn't consider tire size makes perfect sense. If you think about it, the game is centered around modifying your car, and putting upgrades. If i was tuning lets say an STI first thing I'd do to get it track ready is put it wider wheels for more grip. GT5 simply does not have a way to do this. All you can do is choose a different tire.

I am willing to bet that the tire that any given car come equipped with in the game, more or less corresponds to its actual performance. And for any one really interested its easy enough to look up skid pad test results for any car.

 

[VBR]

I am willing to bet that the tire that any given car come equipped with in the game, more or less corresponds to its actual performance. And for any one really interested its easy enough to look up skid pad test results for any car.

In my experience not always: the 111R comes with Sports Hard but should be on Sports Medium, dunno what the Camero SS 2010 comes with but it should be on Comfort Softs, the Maserati GT S 2008 however comes with Sports Hard which is what it should be according to calan's method.


👍

 

[samiazza]

this is by far one of the most interesting threads in gtplanet,

good work Calan, i was testing the stock 05 ford gt yesterday and it was terrible. too much over-steering and not stable at all, which is not the case for this car IRL, and i thought: mmmm the MR cars should have bigger cars in the rear than in front (thats how they are in real right?) so i bought comfort soft and sport medium (in addition to the stock sport hard)

i test it first with sport hard in rear and comfort soft at front, it was more stable and drivable! then i test it with sport medium in rear and sport hard at front and thats how i think the real ford gt should be,

i tried this to all MR super cars such as Ferrari F430, Zonda'z and it was really great, i mean look at the F430 as sample they have 225/35ZR19 at front and 285/35ZR19 at rear and since we cant change the tier width in GT5 so they both (front and rear) SHOULD not be same type, otherwise those cars will not be acting as IRL,,

you can use this site to get the actual tire size for most of the cars: http://www.sizemytires.com/

the same theory applies to the yellow-bird and so many cars in GT5!!! dont you agree

thanks Calan for this great thread i request you to add me my PS is " samiazza "

 

[VBR]

We already covered the tyre width differential issue, read posts 120 to 124 in this thread. I still think that some cars would definately benifit from a softer compound on the rear to compensate for this oversight by PD.


👍

 

[samiazza]

Thanks VBR, Then in order to simulate the real car behaviour we should go for the same google doc. Recomendations but with rear tiers one step softer for the MR cars?

 

[Bobalob]

havnt found this a problem at all. lot of people complaining about what is essensially a lack of skill.

 

[VBR]

Thanks VBR, Then in order to simulate the real car behaviour we should go for the same google doc. Recomendations but with rear tiers one step softer for the MR cars?

Have a read of what calan said in his post here: https://www.gtplanet.net/forum/showthread.php?p=4799353#post4799353

There really is no accurate way of testing it as far as he can think of, but if you did wanna put a softer compound on the rear, or a harder one on the front to try & compensate then what's the harm.


👍

 

[Captain Roh]

Hi Calan 👍

First of all i'd just like to congratulate you on a top notch thread! I use your resource regularly but I dont think i've ever posted to say thank you. So err... Thank You

I'd also like to know if you've ever done any online testing? There are lots of people who consider the tyre compounds to differ greatly in grip levels online, as opposed to a-spec.

Is there any chance you've re created tests online in a couple of your favourite cars? Is there a golden rule when choosing a tyre to use online? For example +/- 0.05 on the skidpad value?

Just wondering

 

[hawkeye122]

You should also consider looking at differential settings... ie: A Mustang wont turn as sharp with out losing grip because of the live axle, but that doesnt necessarily mean Ford fitted garbage tyres...

The Prodrive P2 (Experimental car, not in GT5) had a very advanced diff, so it could do insane turns, but it was only fitted with very run-of-the-mill tyres from a Subaru Impreza...

 

[FoxPT]

Thanks for all this work

 

[Inotus]

So Veyron should run on CS tires? That's crazy...I think it will smoke all tires from standing start. Like Veyron SuperSport on Top Gear track.

 

[ZR1fan]

I run all my exotics on sport softs so they can pacify the juiced cars in various races and have equal grip while maintaining their stock set up, every other production car i run on sports hards, whilst project cars (as in my custom built non RM tuners) get racing mediums and all real race cars get racing softs (i found that the 300ZX chassis in particular had higher mechanical limits than the comfort softs had physical grip.. so to unlock the potential of this car and others i changed my tire plan to completely eradicate comfort tires, and match the AI cars in terms of grip for the exotics).. i dont like unnecessarily modifying cars when a simple tire change is all thats required to wake them up and make them competitive stock.

 

[LVracerGT]

I've seen slightly different numbers for the 2010 Camaro from various reputable sources, and they range from .87 to .91...so I would consider a value of .89 or so to be a reasonable number for that car.

Something you have to remember also, the varying results also depend on tire psi, ambient temp, track (asphalt) temp, and relative grip of the asphalt. You could hand the same car on the same tires to another source on a different day and produce different numbers.

EDIT: after re-reading that, splitting the difference is exactly what I would do.

 

[Thaddaeus]

Dear Sir,
thanks for the great work.
I guess it has been mentioned before, but would you mind posting these results to PD please?
I hope that they can use it to improve the tyre type the Cars come with and also might add something for us to adjust the width of tyres for any given tyre type and car.

I see the fact with the tyre psi, track temp etc... but i know that this is hard to implement and i guess its touching a region where the ps3 simply can not deliver enough computing power.

Edit: Mind putting an auto filter to your Excel sheet for line 1 ? Makes earching way more convinient (like filter for specific brand and no data yet)

 

[shawtyoner]

Great work, I read as much as I could, but this was an area I have always been interested in. Which tire is really a cars STOCK tire. Just want to verify, that the tire PD has chosen for any particular car in GT5, may or may not be its actual real life counterpart? I honestly thought that PD not having every car come equipped with S2 tires (like in GT4), that they had taken the guess work out for us. But you're saying that there are still inconsistencies, and to get the closest driving feel, we should refer to your chart? Thanks again.

 

[VBR]

Hi Calan, I've found another skidpad number for the Volvo C30 R-Design '09, it's 0.89g average, here's the link:

http://www.motortrend.com/roadtests...9_volvo_c30_r_design_test/handling_specs.html

That would put it on Comfort Softs.


👍

 

[shirakawaa]

Great work, I read as much as I could, but this was an area I have always been interested in. Which tire is really a cars STOCK tire. Just want to verify, that the tire PD has chosen for any particular car in GT5, may or may not be its actual real life counterpart? I honestly thought that PD not having every car come equipped with S2 tires (like in GT4), that they had taken the guess work out for us. But you're saying that there are still inconsistencies, and to get the closest driving feel, we should refer to your chart? Thanks again.

Personally, I usually fit tires on stock cars as follows, regardless of the default choice:

- Economy cars (excluding "sporty" Kei cars): Comfort Hard ("Eco Tires")
- Passenger/comfort oriented/medium class cars: Comfort Medium
- Sporty street cars: Comfort Soft
- Supercars/road legal trackday cars: Sport Hard

 

[Kryz11]

I've uploaded a spreadsheet with the recommended tires to Google Docs:

GT5 Stock Tire Recommendations


*************

In an effort to figure out what is going on with GT5's tire models and which tires should go on which cars, I decided to do some skidpad testing. I used the 2010 Camaro SS and the Corvette ZR1, since I'm familiar with those cars and actual data is readily available.

We don't have an actual 200' skidpad to calculate lateral g force with in GT5, but what we do have is a g "meter" and a datalog. For the values I came up with, I created a delineated scale and taped it under the HUD g-force bar graph, and also used a scale against the datalog graph during replays as verification. The measurements were taken on the widest part of the TGTT, by turning a continuous steady-speed circle after warming the tires. Lateral g force was recorded up to the point where the car started to skid and could no longer hold the established circle. I also ran laps "on the edge" to verify the numbers, and repeated all the tests twice. (Note that I rounded the numbers to the nearest .05, due to my screen resolution).

My setup is a racing simulator chassis with a G25 wheel, and a Sony 50" HDTV. I ran each test with no aids and a manual tranny in "bumper" cam. (I hate that inaccurate view name ).

First up was the Camaro, with comfort hard (CH) tires. I performed the test on each tire type, trying to be as consistent as possible. I only tested comfort and sport tires; once I got to the racing compounds the grip started getting ridiculous, and was beyond what I wanted to test with this setup.

Here are the numbers (Notice that each softer tire compound increases lateral acceleration by approximately .05g):

CH - .85
CM - .90
CS - .95
SH - 1.00
SM - 1.10
SS - 1.15

The real-life Camaro SS scores a 0.87 on R&T's skidpad test. So it would appear that CM tires would be closest to stock for the Camaro, based on lateral acceleration. (I'm going to the next higher number, just because ).

Now for the 'vette numbers:

CH - .85
CM - .90
CS - .95
SH - 1.05
SM - 1.10
SS - 1.15

Virtually identical as far as the lateral acceleration numbers for each tire type. The real-life ZR1 scores a 1.10 on R&T's skidpad, so it would appear that SM tires would be the best stock equivalents for it.

Note: Just for reference, RH lateral g values were around 1.25, and RS were around 1.35 with the ZR1.

Here's where it starts getting weird. The real-life Camaro comes equipped with Pirelli P Zero tires, and the ZR1 comes with Michelin Pilot Sport PS2 ZP tires. According to TireRack.com data sheets, both of these tires have identical speed rating (186+mph), tread wear (220), and traction rating (AA).

The only thing I can come up with to explain the unexpected test numbers is that the size of the contact patch is not figured into GT5's tire equations. In other words, to duplicate accurate lateral acceleration numbers for the ZR1, you have to use a softer tire compound to make up for the larger contact patch on the real-life car. (The 'vette has considerably more rubber on the road than the Camaro, especially in the rear).

So far it looks like each car would have to be tested independently to come up with the best GT5 tire type to simulate real life. I plan on doing some more as time permits, but it will be a slow process. First up will probably be one of the Ferrari's that come with the Pirelli P Zero's (599 I think?), so that we have a side-by-side comparison.

Thoughts?

*************

For those that are late to the party and want a quick summary:

My testing so far has revealed that the 9 tire types (CH, CM, CS, SH, SM, SS, RH, RM, RS) in GT5 form what appears to be a simple grip multiplier, with each tire type adding approximately .06g of lateral grip. The only thing that changes is where the scale starts for various cars. (i.e. for the ZR1, CH = .85g and for the '71 Cuda, CH = .80g). It also appears that the width of the tire is not being considered in the grip equations; for any specific tire type, the '02 Mini Cooper has the same amount of lateral grip as the '09 Corvette ZR1! And as softer tires are equipped, the amount of grip increases equally for both cars.

The implications of this are that in order to get close to IRL grip performance (based on lateral acceleration anyway), you have to equip different cars with different tires. As an example, just throwing sport mediums on all performance sports cars means nothing. One car may need CM tires to reproduce IRL performance numbers, while a very similar car may require SH tires.

Here are my "recommendations" for the cars I've tested so far (take it for what it's worth and do with it what will you will ).

Edit: See link at top

Hi can you tell me where how you calculate acceleration Gs? When i go into data loger the acceleration Gs dont have any numbers? all I see is a line graph

 

[Rotorist]

So Veyron should run on CS tires? That's crazy...I think it will smoke all tires from standing start. Like Veyron Super Sport on Top Gear track.

Very nice thought, which led me in the following thoughts:

I believe there is a misunderstanding - logical mistake - in calculating the tire's type for every car only by considering the amount of grip they produce as a whole. The grip of a car is mainly depending from the grip of the tires it has on. That is valid when we change tires on the same car. BUT: If Caterham which weighs 450kgs needs tires of 1G potential (let's say SH) to turn producing 1G lateral acceleration, a vehicle which weighs 2000kgs (i.e. SL65AMG) needs a much better tire to do this, because the impulse the tire takes is much-much greater (4X times regarding the weight) than this on Caterham. So, in order for SL65AMG to achieve 1G grip needs a sports soft or (more possible) a racing tire. In addition there are: the weight distribution, the height of the gravity center, suspension settings, axle of motion. Moreover there is downforce which pushes down the tires and does not increase the weight of the car.

In conclusion, there is no easy way to find out which tire is the correct for each vehicle. The maker know better. So, why not collect info about the tires each vehicle comes with when sold? This is much easier and real IMHO. And don't forget: same type of tire, same price, different maker: entirely different grip. Not every time, but it is very usual.

 

[Rotorist]

Delete

 

[VBR]

DELETE, DOH!

 

[Stotty]

Very nice thought, which led me in the following thoughts:

I believe there is a misunderstanding - logical mistake - in calculating the tire's type for every car only by considering the amount of grip they produce as a whole. The grip of a car is mainly depending from the grip of the tires it has on. That is valid when we change tires on the same car. BUT: If Caterham which weighs 450kgs needs tires of 1G potential (let's say SH) to turn producing 1G lateral acceleration, a vehicle which weighs 2000kgs (i.e. SL65AMG) needs a much better tire to do this, because the impulse the tire takes is much-much greater (4X times regarding the weight) than this on Caterham. So, in order for SL65AMG to achieve 1G grip needs a sports soft or (more possible) a racing tire. In addition there are: the weight distribution, the height of the gravity center, suspension settings, axle of motion.

Not necessarily.

The SL65 will come with much wider tyres than the Caterham...

SL65 f 255/35/19 r 285/35/19
Caterham f 175/13 & r 205/55/13

Almost 50% more contact patch on the SL65.

 

[Rotorist]

You think I didn't consider the tire width? And how is 50% more of the same rubber enough to keep in the same speed & line 5 times (+400%) the mass-weight?

And to correct a mistake of mine: Caterham weighs 370kgs...

 

[VBR]

I dunno if you're still interested in updating your Google Doc calan, but I thought I'd share this website I found anyway:

http://carranking.com/skidpad



👍

 

[alucard0712]

Hello guys!
First of all this is a most interesting thread out there!!!Thanks to author for his work! 👍

My question is about Mclaren F1 and F40, those cars are about same age but you recommend CM for F1, while choice for F40 is SH, does it really goes like this? F40 is even older than F1!

 

[Griffith500]

You think I didn't consider the tire width? And how is 50% more of the same rubber enough to keep in the same speed & line 5 times (+400%) the mass-weight?

And to correct a mistake of mine: Caterham weighs 370kgs...

Slow response, perhaps, but in rigid body calculations, friction force is directly proportional to the vertical load. That is, a given tyre will always give 0.8 g (or so) of lateral acceleration, independent of vertical loading. This is assuming the "friction coefficient" model, which is highly constrained.

Real tyres, however, deform, which is why there are so many different sizes and types for different applications. So a static friction coefficient (w.r.t. loading) is inaccurate for almost all cases, and tyre deformation models are very important at the limit of adhesion.

See here and here for some cool stuff pertaining to tyre modeling in games, and the wider web for confusing, conflicting and often incomprehensible discussions on contact patch size vs. available grip.

Basically, this stuff is not well understood even in the industry itself, outside of their testing.

 

[shirakawaa]

By the way, I don't like the way grip changes with tire consumption in game. Each tire type should act differently. For example fresh road summer treaded tires give their best when they are almost completely consumed (due to the contact patch growing in size as grooves get shallower). Their equivalent in GT5, comfort tires, do not appear to work like this, they just get worst and worst as their consumption increases.

 

[MOTORTRENDmitch]

you should always use Motortrends numbers they are much more accurate and better results

anyways, thats a great job you have done btw, im just curious, how much lateral grip did you pull with the grippiest car you tested?

 

[Exorcet]

Very nice thought, which led me in the following thoughts:

I believe there is a misunderstanding - logical mistake - in calculating the tire's type for every car only by considering the amount of grip they produce as a whole. The grip of a car is mainly depending from the grip of the tires it has on. That is valid when we change tires on the same car. BUT: If Caterham which weighs 450kgs needs tires of 1G potential (let's say SH) to turn producing 1G lateral acceleration, a vehicle which weighs 2000kgs (i.e. SL65AMG) needs a much better tire to do this, because the impulse the tire takes is much-much greater (4X times regarding the weight) than this on Caterham. So, in order for SL65AMG to achieve 1G grip needs a sports soft or (more possible) a racing tire. In addition there are: the weight distribution, the height of the gravity center, suspension settings, axle of motion. Moreover there is downforce which pushes down the tires and does not increase the weight of the car.

In conclusion, there is no easy way to find out which tire is the correct for each vehicle. The maker know better. So, why not collect info about the tires each vehicle comes with when sold? This is much easier and real IMHO. And don't forget: same type of tire, same price, different maker: entirely different grip. Not every time, but it is very usual.

Normal force takes car of that. Scale a car's weight up by 2 and it will still pull the same lateral g, assuming all else is the same.

This tire assignment thing isn't perfect, but that's mostly because of how limited GT5's tire modeling is. I think the guide outlined here is very good. Far better than what GT5 assigns as stock tires.

Comfort Soft seems like the best choice for sporty road cars/supercars. More then enough grip to fly around a race track, but not enough to prevent the driven wheels from breaking loose when pushed too hard.

 

[devildog666]

I've uploaded a spreadsheet with the recommended tires to Google Docs:

GT5 Stock Tire Recommendations


*************

In an effort to figure out what is going on with GT5's tire models and which tires should go on which cars, I decided to do some skidpad testing. I used the 2010 Camaro SS and the Corvette ZR1, since I'm familiar with those cars and actual data is readily available.

We don't have an actual 200' skidpad to calculate lateral g force with in GT5, but what we do have is a g "meter" and a datalog. For the values I came up with, I created a delineated scale and taped it under the HUD g-force bar graph, and also used a scale against the datalog graph during replays as verification. The measurements were taken on the widest part of the TGTT, by turning a continuous steady-speed circle after warming the tires. Lateral g force was recorded up to the point where the car started to skid and could no longer hold the established circle. I also ran laps "on the edge" to verify the numbers, and repeated all the tests twice. (Note that I rounded the numbers to the nearest .05, due to my screen resolution).

My setup is a racing simulator chassis with a G25 wheel, and a Sony 50" HDTV. I ran each test with no aids and a manual tranny in "bumper" cam. (I hate that inaccurate view name ).

First up was the Camaro, with comfort hard (CH) tires. I performed the test on each tire type, trying to be as consistent as possible. I only tested comfort and sport tires; once I got to the racing compounds the grip started getting ridiculous, and was beyond what I wanted to test with this setup.

Here are the numbers (Notice that each softer tire compound increases lateral acceleration by approximately .05g):

CH - .85
CM - .90
CS - .95
SH - 1.00
SM - 1.10
SS - 1.15

The real-life Camaro SS scores a 0.87 on R&T's skidpad test. So it would appear that CM tires would be closest to stock for the Camaro, based on lateral acceleration. (I'm going to the next higher number, just because ).

Now for the 'vette numbers:

CH - .85
CM - .90
CS - .95
SH - 1.05
SM - 1.10
SS - 1.15

Virtually identical as far as the lateral acceleration numbers for each tire type. The real-life ZR1 scores a 1.10 on R&T's skidpad, so it would appear that SM tires would be the best stock equivalents for it.

Note: Just for reference, RH lateral g values were around 1.25, and RS were around 1.35 with the ZR1.

Here's where it starts getting weird. The real-life Camaro comes equipped with Pirelli P Zero tires, and the ZR1 comes with Michelin Pilot Sport PS2 ZP tires. According to TireRack.com data sheets, both of these tires have identical speed rating (186+mph), tread wear (220), and traction rating (AA).

The only thing I can come up with to explain the unexpected test numbers is that the size of the contact patch is not figured into GT5's tire equations. In other words, to duplicate accurate lateral acceleration numbers for the ZR1, you have to use a softer tire compound to make up for the larger contact patch on the real-life car. (The 'vette has considerably more rubber on the road than the Camaro, especially in the rear.

A couple of things you forgot to consider, the camaro weighs about 500lbs more than the 'vette and the 2 cars have different suspension set ups that would affect the results.