Custom wheels give all 4 tyres the same width.... changes grip and balance

[DonJo76]

The one thing you seem to forget is when standing still then full throtlle, with the diablo you will notice it

 

[andryush]

[SIZE=4][B][URL='https://www.gtplanet.net/forum/members/mr-shakotan.240170/']Mr Shakotan[/URL][/B][/SIZE]

Well, i have no real benefit in faking results of my "research" this is only a video game. This lap times were made with same car, same setup, same effort, only different rims.

if this difference in driving experience isn't apparent to you, that's good for you, because you can drive without taking the notice of worsening grip of rear axle) I feel the difference and in my opinion PD should either fix this bug or give us an option to freely customize wheel sizes. Physics engine for sure can handle it properly, from graphics standpoint there should also be no problems with this feature.

 

[Mr Shakotan]

I am not being a jerk when i say this but If this is 100% true why are my lap times getting better and every so many laps a few get worse. I am at the point where I am leaving no stone unturned I am not even using the stock wheels anymore I am now trying too beat my best lap time on stock wheels with custom wheels and Im getting within a sec of doing so. Just too prove too myself that if real this wont be a problem for me. If I sat here for another 20-40 mins I am sure i could beat the best lap time but in ten mins I am about to leave for a while and wont be able to play until again till tonight. I have added my own variable too this theory by drifting the car to see if this would effect my drifting line or rear end grip and I also am getting better lap time with each pass and a few with slower times. So all i can say if this is true learn to overcome this cause if this is true I have already adapted to this and getting better each pass without yet noticing the adverse affect. I have even tried this with the weakest sway bar setting's. If true then dam PD WTF but a skilled person will overcome this. If it over steer's use over steer to your advantage it is by all means a rwd car in the first place. If its really that bad for you then I guess stock wheels for you. Cause I doubt if a real problem PD is fixing this anytime soon. Later on when I get back i am going too also try this online with players who I am sure are always on there best A game and have the money too waste on a RGT to try this with me and see if they notice without telling them why and see what happens

 

[Mr Shakotan]

[SIZE=4][B][URL='https://www.gtplanet.net/forum/members/mr-shakotan.240170/']Mr Shakotan[/URL][/B][/SIZE]

Well, i have no real benefit in faking results of my "research" this is only a video game. This lap times were made with same car, same setup, same effort, only different rims.

if this difference in driving experience isn't apparent to you, that's good for you, because you can drive without taking the notice of worsening grip of rear axle) I feel the difference and in my opinion PD should either fix this bug or give us an option to freely customize wheel sizes. Physics engine for sure can handle it properly, from graphics standpoint there should also be no problems with this feature.

If your faking it or not isn't the point your posted pic of lap times gives no data just times they could mean anything. Doesn't matter if your honest or not it doesn't show anything but time not what you did to get the time or setup you was using. Even if it did it doesn't rule out driver error. All it really is is a pic of lap time and nothing more

 

[sailworksman]

I always thought the wider the tire, there is more of a contact patch, therefore better grip. I went up 2" on my Yellowbird. I'll try tonight and see what happens.

 

[andryush]

If your faking it or not isn't the point your posted pic of lap times gives no data just times they could mean anything. Doesn't matter if your honest or not it doesn't show anything but time not what you did to get the time or setup you was using. Even if it did it doesn't rule out driver error. All it really is is a pic of lap time and nothing more

Well, you have to believe in what i am saying I can't provide you with exact data on what car i was using and its setup))) If you want, i can upload my ghost data, and you can see for yourself that i wasn't cheating to make 1.2s better time.

I am not being a jerk when i say this but If this is 100% true why are my lap times getting better and every so many laps a few get worse. I am at the point where I am leaving no stone unturned I am not even using the stock wheels anymore I am now trying too beat my best lap time on stock wheels with custom wheels and Im getting within a sec of doing so. Just too prove too myself that if real this wont be a problem for me. If I sat here for another 20-40 mins I am sure i could beat the best lap time but in ten mins I am about to leave for a while and wont be able to play until again till tonight. I have added my own variable too this theory by drifting the car to see if this would effect my drifting line or rear end grip and I also am getting better lap time with each pass and a few with slower times. So all i can say if this is true learn to overcome this cause if this is true I have already adapted to this and getting better each pass without yet noticing the adverse affect. I have even tried this with the weakest sway bar setting's. If true then dam PD WTF but a skilled person will overcome this. If it over steer's use over steer to your advantage it is by all means a rwd car in the first place. If its really that bad for you then I guess stock wheels for you. Cause I doubt if a real problem PD is fixing this anytime soon. Later on when I get back i am going too also try this online with players who I am sure are always on there best A game and have the money too waste on a RGT to try this with me and see if they notice without telling them why and see what happens

Your lap times getting better and better no matter which rims are installed...
Either you are very skilled player, or the opposite - you put not enough effort in making fastest lap times and you progress slowly with it Or both.

In my case, this was my first ride in RGT, I configured suspension for it, and when I decided that this setup is the best i can get from it, then i drive for few laps. Few tweaks, few laps and i made my fastest lap in it, i couldn't go faster than that, I knew that i'm near my personal limit with this car.

Then i changed to stock wheels, on first lap I beat my best time by 1.2 second. How would you explain this? Before I was driving hell out of this car, after changing to stock wheels, with minimal effort i'm faster by 1.2 second...

 

[Awong124]

I always thought the wider the tire, there is more of a contact patch, therefore better grip. I went up 2" on my Yellowbird. I'll try tonight and see what happens.

Having a wider tire doesn't increase the contact patch size, it just changes its shape. Contact area is a function of the weight distributed to each corner of the car and tire pressure.

 

[Flaren89]

Yea, i've tried right now and it is true... I was about to ask myself why my fully tuned Aventador was so hard to control on the rear other than the great power/torque (which is only 70% on the rear anyway, not full)... I applied on it custom wheels...
Had a hard time also with Gallardo GT3-like tuned and felt a difference on my 643PP GT-R Black Edition from when i applied Rays rims, but at a first moment i didn't give it so much importance...

After reading here and watched the difference in the Photo Travel mode, i installed again all original rims in my cars... I've also taken a couple of photos of MP4-12C GT3-like tuned and 458 Italia GT3-like tuned in comparatives with their stock counterparts, tomorrow i'll post you pictures here...

For the laptimes, i can assure you that with the Gallardo i improved from a hard-control 2:06.high (with custom rims) to a easier-to-handle 2:03.low in 2 laps (with stock rims) @ Silverstone GP...

 

[HuskyGT]

Does PD even know about this bug? It needs to be fixed asap.

Until it gets fixed, say I'm using a 135/E92 M3/Boss Mustang/M5 with custom wheels. If I want it to act like it had the proper tire widths, I should be using Sports Hard tires?

I can tell you for certain that you shouldn't worry about these cars. They are not affected performance wise, due to how small the stagger is in them.

Even the mighty M5 with its 500HP doesn't suffer one bit. The good thing is that the difference with the stock tires is so small that you will barely notice a visual difference. However, it is not entirely unnoticeable, and PD should fix it.

Sport Hard Tires sounds about right. It's the tires I'm using with these cars for now.

 

[raven214]

I always thought the wider the tire, there is more of a contact patch, therefore better grip. I went up 2" on my Yellowbird. I'll try tonight and see what happens.

Umm, isn't the 2" referring to the increased size of the rim (and accordingly decreased size of the tire wall) rather than the width of the tire? The rim size has nothing to do with the contact patch, though the change in tire wall would have its own affect (if it is modeled).

 

[Flaren89]

@HuskyGT

As the description of the tires compound says, in the Comfort compound there is something like "These are the tires used by stock cars and are the best for players that want to feel the most realistic driving" (dunno if it's correct, i just translated from my language)... This means that sportcars, supercars and even hypercars need to get a downgrade on the tires from Hard Sport to Soft Comfort... For the same reason, it is better to downgrade tires of all stock cars, so those have Soft Comfort need to downgrade to Medium and from Medium to Hard... I do this for my stock cars records that i upload on my youtube channel...

Obviously, don't change compounds on race cars...

 

[Awong124]

Supposedly, Sports tires are like R-compounds, street legal competition tires. Some high performance street cars do come with R-compounds from factory.

 

[Flaren89]

We are OT by talking about the tires compounds, anyway, for tell you why i do that, it's because of laptimes...
I did some tries with 458 Italia with Hard Sport and Soft Comfort, the result is that with the first, i did from 2 to 3 seconds better than real laptimes record, with the Comfort i did the same to 0.5 better... The fact that me (a never-true-life-driven-races) can do the same times as professional drivers it can be related to the non-100% simulation nature of the game...
To improve this my theory, I can say that with the Z4 GT3 @ Silverstone GP i do just 1.5 second better than what i can do on Simraceway (a PC sim) and almost the same time that skilled players can do in that game which is almost the same of the real-life, so the racing compounds are optimal considering again the non-100% sim-wise of GT6...
The only one that are "messed-up" should be Hard Sport, but again, for my theory u should install Soft Comfort, which enter again in the "real-life vs GT6" optimal comparison...

 

[Amac500]

Same thing happened to me. After a lot of game freezes, my PS3 would no longer read any disc. Unit has been sent back to Sony for repair. I am out $100 thanks to gt6! GameStop said it was probably a coincidence. Hmmmm.

I ordered another laser for like $30 and I shoulda got it Tuesday but didn't and it was suppose to be delivered yesterday but wasnt, so I better get it today, been without it for a bit over a week now.

 

[eSZee]

I can tell you for certain that you shouldn't worry about these cars. They are not affected performance wise, due to how small the stagger is in them.

There is definitely a difference in the 135i.
The car was one of my favorites early on. It had a set of RPF1s on it from the get go, before I knew of the wheel glitch. It was a blast. Great turn in. Easily induced and controlled power slides.
Put stock wheels back on and it understeered pretty badly. My average on Brand's Hatch Indy is .4-.5s faster with aftermarket wheels.
I'm still not sure whether the 135i in game is running on the stock 18" wheels or the optional 17" wheels though.

 

[Fgame]

Having a wider tire doesn't increase the contact patch size, it just changes its shape. Contact area is a function of the weight distributed to each corner of the car and tire pressure.

That's incorrect. If I put tyres 1m in width, they would give a far larger contact patch than tyres with 0.2m width.

But more realistically you can use this calculator here.

http://bndtechsource.ucoz.com/index/tire_data_calculator/0-20

 

[sailworksman]

Umm, isn't the 2" referring to the increased size of the rim (and accordingly decreased size of the tire wall) rather than the width of the tire? The rim size has nothing to do with the contact patch, though the change in tire wall would have its own affect (if it is modeled).

The original post shows a wider tire on the left. I was thinking when you change the diameter, the width changes too? Wider would mean an increase in grip.

 

[Awong124]

That's incorrect. If I put tyres 1m in width, they would give a far larger contact patch than tyres with 0.2m width.

But more realistically you can use this calculator here.

http://bndtechsource.ucoz.com/index/tire_data_calculator/0-20

I remembered reading that somewhere. I guess it was wrong. It seemed to make sense, but I guess it's not true then.

 

[eSZee]

The original post shows a wider tire on the left. I was thinking when you change the diameter, the width changes too? Wider would mean an increase in grip.

Only diameter changes.

 

[Vagabond]

I am not being a jerk when i say this but If this is 100% true why are my lap times getting better and every so many laps a few get worse.

With so many people giving testimony that confirms this glitch is real in terms of grip loss, you're paddling upstream mate. I've been at this GT thing a fair while now and I've a proven track record when it comes to lap-times and car setups. Maybe you're getting faster because you're still finding the limit...? I can find the limit pretty fast and believe me, it is reached alot faster with skinny rear tyres. This is not a visual anomaly, it is an error that substitutes wider rear tyres for front tyres. Its a fact and your watered down debate is, quite frankly, becoming irritating.

 

[HuskyGT]

There is definitely a difference in the 135i.
The car was one of my favorites early on. It had a set of RPF1s on it from the get go, before I knew of the wheel glitch. It was a blast. Great turn in. Easily induced and controlled power slides.
Put stock wheels back on and it understeered pretty badly. My average on Brand's Hatch Indy is .4-.5s faster with aftermarket wheels.
I'm still not sure whether the 135i in game is running on the stock 18" wheels or the optional 17" wheels though.

Hmm. I must try this. I didn't drive the 135i with the stock wheels. I've always known this car for being very oversteery, so I supposed it was normal to be losing the rear end constantly.

 

[RSnider]

Even if so how can you accurately test this with results set in stone. If i was a programmer wouldn't matter how much they pay me too do it I would not for one make a visual change affect performance that's just stupid and i would assume a program is far from that at the very least with programming. Two It doesn't make sense to program or make a line of code like this too have a negative effect. Why didn't anybody catch this while testing the game before production? Why in the wheel description tab of the wheel selection screen does it not at least give the disclaimer for a heads up? I am sure they tested the wheel option on every car they are available to at the very least see if visually it would even render or not crash the program. If its as bad as implied somebody would have noticed this while testing, and would have did something about it, after from all the GT games of people complaining about wheel choices. That had to be one of the biggest gripes about the game since GT1, so I don't buy it. And I also wouldn't waste the extra time and programming effort to program a performance difference from a visual effect, it be extra work for nothing and too only get a negative affect. Who on here can pull or run or read code to confirm this? Now i have only had the game about 6 days and I haven't gone trough every option, course, or car, but i think in previous game the course anylizer show your input of gas, brake, e-brake, braking and accel point, steering input, or generally what you were pressing during the replay. I am not sure if this is still possible, but if it is you should be able to take replay of with and without wheels and see if your even doing the exact same speed the same time in the same speed and position on the track. It be the closest thing you could do to at the very least too even see how much driver error or improvement you have. Other than pulling the code or viewing the programming it really would be the only way too confirm this going of just a slower lap time isnt enough evidence that this is actually happening. Im sorry its not. Until we get a PD person, a hacker or a person well experianced with pulling reading and understanding code, all you have is a theory. Im sorry i am not trying too be difficult so excuse my transgression or doubt i just don't see where there is even enough data too support this theory

That's where you're wrong; it isn't JUST a visual change. In all previous versions of Gran Turismo, you would be correct; changing wheels is strictly a visual change. However, starting in Gran Turismo 6, PD developed an actual tire model to allow for a more realistic simulation. In the real world, a tire's contact patch is constantly changing as the tire experiences different loads. A larger contact patch typically yields more grip. A wider tire means a larger contact patch. Instead of treating the tire as a fixed, rigid body (as in all previous versions of GT), GT6 models it as a flexible body. The problem is due to a programming error that causes the rear wheels of some vehicles to be replaced with a narrower counterpart. And because the tire model takes into account width, the narrower tires effectively reduce the available grip at the rear.

You place too much faith in PD's quality control testing. If they tested every minute aspect of the game (as you suggest they do) then there is no reason for the game to have any bugs at all and I think we can all agree this isn't the case. Not every bug gets caught in testing, especially in today's game market where everything is pushed out as quickly as possible. The game has bugs. This is a bug. It wasn't caught in testing. It's as simple as that.

If you don't believe all the evidence in this thread, get one of the RUFs, change the wheels, and see for yourself.

 

[BuzzRazer]

Didn't they update this in lates patch?
RUF's are just hard to control IMO.

 

[eSZee]

Didn't they update this in lates patch?

They did not.

 

[LS Chiou]

Tried Huayra, Cizeta V16T, RUF B/CTR.. and a few high power FR sport cars, they all suck with custom wheels. Rear tire temperature indicators turn orange even in the straight line, not to mention in the bend. They just give up way too early.

And its funny that in the setting menu screen, with the car rotating by R1/L1, I can see the width of rear tires are unchanged with custom wheels. But when I drive them out for a test, handling suck aside, they shrink in width obviously in the replay.

 

[sailworksman]

I can confirm that the OP may be correct. I used 2 different Yellowbirds, identical setups at 550pp. The car with the 2" larger rim size was a handful, as well as tire temp differences. It was sliding all over the place. There is some validity to this.

 

[dranzer19]

I didnt want to believe this but its very true. I did a tune in my e92 M3 with stock rims and after i was done i fitted rims without thinking about this issue, but as soon as i did that the car started acting really weird. I read this thread afterwards stating it ruined the grip on rear tires but i could confirm that it actually affects all four tires as well

 

[Flaren89]

Here the comparisons i did yesterday evening:

Ferrari 458 Italia GT3-like tuned with aftermarket rims vs stock with stock rims:

McLaren MP4-12C GT3-like tuned with aftermarket rims vs stock with stock rims:

There are also tyre compound differences, but it shows how rims change the ground width contact of the rear tires (with stock rims, racing tires get proper and true width)...

 

[Vagabond]

I can confirm that the OP may be correct. I used 2 different Yellowbirds, identical setups at 550pp. The car with the 2" larger rim size was a handful, as well as tire temp differences. It was sliding all over the place. There is some validity to this.

Without meaning to sound pissy, I already know with absolute certainty that I am correct and its already been confirmed by many others. There is not "some validity" - its an absolute fact beyond contestation. Why are we still debating this? I made the thread as an informative announcement so people don't wonder why their car is behaving strangely if they've fitted custom rims, not to go round and round in circles with people who, for some reason, choose not to accept it as fact.

 

[Flaren89]

I gave my contribute yesterday up ahead and right before you right for those ppl that can't stand the truth...
1 can be a bad tought, 2 can be a coincidence, 3 can be a hard coincidence, 4 can be a possibility, 5 it's a serious possibility, 6 it's an almost certain, 7+ it's an absolute valid thesis, if there aren't other things in play like "data error downloaded just for some"...