Tire Testing - Strange, but interesting results...

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

GT5 Stock Tire Recommendations


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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?

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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

You have too much free time

Good job, but what ^ said! At least you are not out grinding so good for you =)

Nah... I'm just a racing nut. My IRL hotrod is up on jack stands for some work over the winter, so I might as well play around with some fantasy hot rods. Besides, it keeps me out of the bars and the boss lady off my back.

My biggest gripe is with the tire wear in this game. So far, racing hards, mediums, and softs all last the same amount of laps for me.

Its strange that I can only go the same amount of laps that racing softs can do, in racing hards.

But good job on your testing.👍

You should definately get XP for this

Good job, very nice.

I find these scientific tests to figure out the very details of the game really interesting. After all, one often finds data which improves the realism of playing GT5 through bringing the game closer to its real life counterparts.

Good work, keep it up! 👍

Good data... On the subject of grinding maybe you could take your SS & ZR1 around Indy and see how many laps you get off each tyre compound. Then all the tyre data we need is right here in your thread

This is a very interesting comparison. I usually use sports hard on all performance cars in aim of simulating a max. performance street tire. I found it provided a somewhat realistic performance to the real-life counterpart but was not applicable to all cars.

In for more results:tup:

What I'm hoping for is that after testing a few more cars with known data, the pattern I have found so far holds and we can just use real-life skidpad numbers to assign the proper tire.

I'll be a bit surprised (and disappointed) if I see about the same results with each tire type across radically different cars. I just can't fathom a FF Civic pulling a 1.1g on SM tires.

We'll see...

The next question that pops up in my head is: would the correct choice of tires based on real life skidpad figures also reflect the correct values for traction and braking distances?

the Interceptor

The next question that pops up in my head is: would the correct choice of tires base on real life skidpad figures also reflect the correct values for traction and braking distances?

Click to expand...

That was one of the first things that popped in my head also, but I can't figure out a good way to test it. There aren't any accurate ways to measure distance, and using the cones on TGTT doesn't work because the skid marks aren't persistent.

I'll focus on the skidpad stuff for now; someone else feel free to jump in with the acceleration and braking tests.

I think they chose the best tire to mimic the real car's characteristics. I remember buying an Evo IX in GT5 and seeing that it has Comfort Soft Tires and got shocked. The Evo's tires in real life are anything but comfort. They last around 10k miles and in the game should be close to SM.

Also the BMW M3 CSL has slicks in real life while in GT5 it has SH. The GT5 equivalent should be RH.

Very interesting stuff. I look forward to seeing what else you discover.

StogyBear

I think they chose the best tire to mimic the real car's characteristics. I remember buying an Evo IX in GT5 and seeing that it has Comfort Soft Tires and got shocked. The Evo's tires in real life are anything but comfort. They last around 10k miles and in the game should be close to SM.

Also the BMW M3 CSL has slicks in real life while in GT5 it has SH. The GT5 equivalent should be RH.

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Comfort just means road tyres. It doesn't mean they are built for comfort that's just the name PD chose for road tyres. The Evo would obviously be fitted with soft grippy road tyres as standard irl, not semi slicks as you suggest.

Also the BMW M3 CSL would certainly not be fitted with slicks irl as it is a road car. It would possibly have semi slicks fitted which is what sports tyres mean in GT5.

Hard semi slicks makes perfect sense for this car. Racing slicks do not as they are not road legal.

Just incase your still confused.

Comfort = Road tyres.

Sports = Semi slicks.

Racing = Slicks.

Whether or not the different types of tyres give realistic grip values is what this guy is testing.

i undestand that in GT the tyres work like this. say you have a focus and a ferrari. the focus in real life comes with tyres that arent that wide. say 14-15 inch rims on 70-80sidewall, 180 width; fairly standard non performance economy tyres. a ferrari will come with 18inch, 40-50sidewall, 250+ width. more performance minded. in GT you select the rubber compound to that size. so you buy racing-hard compound in those tyres sizes for the focus and the ferrari, the 250-45-18R ferrari tyre will give more performance than the focus' 180-75-15R tyre, both with same rubber compound "stickiness". so you would need a softer compound in the focus' size to have similar performance.

EDIT: i cant remember if it was the M3 GTR or CSL that came with very soft performance road tyres where you had to sign a waiver acknowledging that you understood that you were not suppost to drive it in wet conditions as the tyres where more suitable for dry running.

StogyBear

Also the BMW M3 CSL has slicks in real life while in GT5 it has SH. The GT5 equivalent should be RH.

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Mine didn't, I don't think any did. They were semi-legal road tires, barely gripped in the wet but great in the dry.

EDIT: It was the CSL Madman - although it was more of a gimmick as Pilot cups were 'ok' in the wet but certainly not something you'd use daily.

Don't forget to factor in weight as well as contact patch. The Camaro is a lot heavier than the ZR1 - 3800lbs versus 3350lbs. Applying schoolboy physics (probably a bad move!) I'd expect the Vette to pull somewhere around 15% better lateral-G if everything else such as contact patch, suspension, etc were equal (which of course it isn't!). Still, based on 0.87g for the Camaro that would give about 1.0g for the ZR1. OK, I know it's bad physics...

A quick-and-dirty way to double-check those numbers would be to run a simple 0-60mph test. That way we could see if the most accurate tire for skidpad corresponds to the most accurate tire for acceleration... or if it's all a crapshoot (which I suspect it might be).

Madman Apex

...both with same rubber compound "stickiness". so you would need a softer compound in the focus' size to have similar performance.

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But that isn't the case in GT5; it's right the opposite. With the Camaro and ZR1 both wearing essentially the same shoes (and assuming GT5 compensates for the tire sizes, weight, etc), you would expect tire x on the ZR1 to pull a better number than the same tire on the Camaro, since it is wider on the ZR1 and that car corners better (which is exactly what happens IRL). But it doesn't happen in the game; the same tire pulls equivalent numbers on both cars. So to get results that match real world numbers, you have to put a softer tire on the better handling car, which means something is off somewhere in the calculations. It almost looks like GT5's physics engine considers at least these two cars to have the same size tires.

Y8ODY

Don't forget to factor in weight as well as contact patch. The Camaro is a lot heavier than the ZR1 - 3800lbs versus 3350lbs.

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True...but since we have a final lateral g number to shoot for, we (I) don't really care how the game gets there internally. If the real-life Camaro pulls a .87g, then a stock Camaro in GT5 should pull that same number as well. If the weight and suspension are correctly modeled, that only leaves the tire compound to play with, since we can't change the tire size. (I am testing the cars in stock trim with no mods BTW).

Evil_Stig

A quick-and-dirty way to double-check those numbers would be to run a simple 0-60mph test. That way we could see if the most accurate tire for skidpad corresponds to the most accurate tire for acceleration... or if it's all a crapshoot (which I suspect it might be).

Click to expand...

I suspect the acceleration test would be more of a crap shoot, given the inconsistencies with the trannies, low-speed physics, etc.

freejrs

Just incase your still confused.

Comfort = Road tyres.

Sports = Semi slicks.

Racing = Slicks.

Whether or not the different types of tyres give realistic grip values is what this guy is testing.

Click to expand...

Ok so the difference between a Dihatsu midget's tires and an Evo's tires is just one tire grade? And the CSL has the same tires as a regular sports car like the 135 or a 370z?

I see what you're saying but it doesn't make sense. I thought sports tires in GT would be higher quality advans (like the evo's) and comfort would be the cheap tires you get on your Accords and Altimas.

calan_svc

I suspect the acceleration test would be more of a crap shoot, given the inconsistencies with the trannies, low-speed physics, etc.

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I don't want to hear your excuses! Now, get cracking!

StogyBear

Ok so the difference between a Dihatsu midget's tires and an Evo's tires is just one tire grade? And the CSL has the same tires as a regular sports car like the 135 or a 370z?

I see what you're saying but it doesn't make sense. I thought sports tires in GT would be higher quality advans (like the evo) and comfort would be the cheap tires you get on your Accords and Altimas.

Click to expand...

That's what we are here to find out.

So far it looks like the tire descriptions don't actually mean anything in particular. My hunch is that the tire selection is going to turn out to be a linear grip multiplier that goes from 1-9, and the "comfort", "sport", and "racing" labels were just thrown on for GP, with artwork on the cars to match.

That's what I think too. I think they program the car's physics with the stock tires, then if you decide to buy a better tire, it just adds to the grip.

Unfortunately, I don't think skidpad numbers will really tell you how the tires behave in GT5. While you may be able to match the skidpad results, that doesn't mean the braking and acceleration will match. For instance, you say that Sports Medium tires will most closely match the grip of the ZR1 in GT5. However, testing on the same track (TG:TT) I was able to pull lap times over 2 seconds quicker than the real life car by using Sports Hards. That would indicate that the Sports Hards actually provide more grip than what the real car has, given that the weight and power were stock.

A couple more things to consider:

1) Tire grip is heavily dependent on the testing surface. Asphalt has vastly different grip properties than concrete, and different formulations of each can also change the grip level. I don't know how well this is simulated in GT5, but I'd bet different tracks have different grip levels to a certain extent.

2) The skidpad diameter does actually make a significant difference in the average lateral-G. Some magazines use 200ft diameter, some use 300ft, and so on. You should try to mimic the general size in order to achieve the same results. Also, the numbers you see are AVERAGE lateral-G, not peak. The best you can get on GT5 is to try to hold a steady radius turn and estimate the average, but that's going to be difficult.

3) Magazine testing is really inconsistent. One magazine can pull .87G with a Camaro, and another may pull .92G. This is why I say that skidpad numbers aren't necessarily a great indicator of overall tire performance in GT5.

Regardless, I do applaud you for taking a scientific approach, but I fear that these questions will never be satisfactorily answered. No harm in continuing to try, though

Great job, looking forward to more data!

sumbrownkid

My biggest gripe is with the tire wear in this game. So far, racing hards, mediums, and softs all last the same amount of laps for me.

Its strange that I can only go the same amount of laps that racing softs can do, in racing hards.

But good job on your testing.👍

Click to expand...

Ive heard this before, but when I did the grand valley ( I think.. or was it tsukuba?) my race hard tires lasted 30 laps, race mediums 20 laps, and race softs 10 laps. All pitted when it was 40-50%

What tires the "2010 Camaro SS" comes equipped with when you purchase it? I want to know if the tires equipped are "true to life" (with respect to the lateral acceleration test you have provided) when you purchase a car from the dealer. Or if we have to change the tires to receive such results...

I'm at work right now, but someone feel free to perform the same test as I described and post up some results. Use a car from this page, so we have accurate real-life data to compare with.

You just need to be careful that you are on a consistent circle and watch closely for when you can no longer hold it. (And make a masking tape scale to put under GT5's g force bar graph for better accuracy).

I used the "Chicago" area on the TGTT where the lanes cross, by the tires. There are various marks in the concrete there that you can use as a reference for establishing a circle.

JTSnooks

Unfortunately, I don't think skidpad numbers will really tell you how the tires behave in GT5. While you may be able to match the skidpad results, that doesn't mean the braking and acceleration will match. For instance, you say that Sports Medium tires will most closely match the grip of the ZR1 in GT5. However, testing on the same track (TG:TT) I was able to pull lap times over 2 seconds quicker than the real life car by using Sports Hards. That would indicate that the Sports Hards actually provide more grip than what the real car has, given that the weight and power were stock.

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I do completely agree with what you've posted (that I've eliminated to shorten the length of the quotation), but there is also one more thing you have to consider... It may not necessarily be the choice of tires, but the lack of fear created from the G's / speed you'd feel in real life that allows you to get a faster lap time.

timeatkuu

What tires the "2010 Camaro SS" comes equipped with when you purchase it? I want to know if the tires equipped are "true to life" (with respect to the lateral acceleration test you have provided) when you purchase a car from the dealer. Or if we have to change the tires to receive such results...

Click to expand...

Uhhh... did you read the first post? That is what this thread is all about.

JTSnooks

Unfortunately, I don't think skidpad numbers will really tell you how the tires behave in GT5. While you may be able to match the skidpad results, that doesn't mean the braking and acceleration will match. For instance, you say that Sports Medium tires will most closely match the grip of the ZR1 in GT5. However, testing on the same track (TG:TT) I was able to pull lap times over 2 seconds quicker than the real life car by using Sports Hards. That would indicate that the Sports Hards actually provide more grip than what the real car has, given that the weight and power were stock.

Click to expand...

I think it just indicates that you are able to drive a faster lap on a game, rather than in real life where money and life are at risk.

JTSnooks

1) Tire grip is heavily dependent on the testing surface. Asphalt has vastly different grip properties than concrete, and different formulations of each can also change the grip level. I don't know how well this is simulated in GT5, but I'd bet different tracks have different grip levels to a certain extent.

Click to expand...

Agreed, but this testing is all relative; not absolute.

JTSnooks

2) The skidpad diameter does actually make a significant difference in the average lateral-G. Some magazines use 200ft diameter, some use 300ft, and so on. You should try to mimic the general size in order to achieve the same results. Also, the numbers you see are AVERAGE lateral-G, not peak. The best you can get on GT5 is to try to hold a steady radius turn and estimate the average, but that's going to be difficult.

Click to expand...

Pad radius only matters when using vehicle speed to mathematically calculate the lateral grip. But we aren't doing this in the game (not that we could anyway). I am simply using GT5's built in lateral g-force data logging, which in theory has already compensated for speed and turning radius.

You bring up a good point that I forgot to mention; I am using the average value, not peak.

JTSnooks

3) Magazine testing is really inconsistent. One magazine can pull .87G with a Camaro, and another may pull .92G. This is why I say that skidpad numbers aren't necessarily a great indicator of overall tire performance in GT5.

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Agreed. I chose to use Road and Track numbers, since they are one of the old school originals and their methods are seen as somewhat "standard".

StogyBear

I think they chose the best tire to mimic the real car's characteristics. I remember buying an Evo IX in GT5 and seeing that it has Comfort Soft Tires and got shocked. The Evo's tires in real life are anything but comfort. They last around 10k miles and in the game should be close to SM.

Click to expand...

Maybe, as the figures suggest, GT programmers just gave the game 9 tire stickness (not necessarily comfort, sport and race. those are just names) and 3 tire wear models repeated three times. They just take real life numbers and gave the game cars the equivalent stock tires, without any regards to all the previously mentioned factors (contact patch, side wall stiffness etc). If a car by chance landed in a soft rating, it is given that particular tire wear model, even though in real life, it could pull those numbers on hard tires.

So basically, they just took the easy way out it seems, but after all, it is just a game.

So my question is, will a car that came with comfort tires as stock in the game be able to pull the same numbers in real life as the race soft tires in the game. if it is impossible, should the game restrict you from equipping it?