Scientific study on tire grip and pre-programed traction control systems

[~el~jefe~]

Has anyone come across hard data regarding the interchange between tire grip, friction coefficient, flex, etc, and the pre-programed DSC/Traction control systems in cars like ours?

I wonder about that. it is commonly known that the OEM tires are designed to provide the right grip and slip for the car, and my new 2017 BRZ has a specific system designed now to allow a lot more slip in Track mode. If it came on and was aggressive in its actions, and had aggressively gripping tires non-oem, both with torque control and vector braking, it would underperform, I would think.

I do wonder if anything but the OEM tires actually work with the very dialed in and specific engineering that went into the car.

[Tcoat]

Originally Posted by ~el~jefe~

Has anyone come across hard data regarding the interchange between tire grip, friction coefficient, flex, etc, and the pre-programed DSC/Traction control systems in cars like ours?

I wonder about that. it is commonly known that the OEM tires are designed to provide the right grip and slip for the car, and my new 2017 BRZ has a specific system designed now to allow a lot more slip in Track mode. If it came on and was aggressive in its actions, and had aggressively gripping tires non-oem, both with torque control and vector braking, it would underperform, I would think.

I do wonder if anything but the OEM tires actually work with the very dialed in and specific engineering that went into the car.

The cars come with at least 3 different types of tires depending on market area so I doubt they are dialed into the system that precisely.

[~el~jefe~]

how would then going to something like a MIchelin pilot ss be then? that's immensely more grippy.

I am not going to get them though, I will be gettin your AS 3+ like you recommended. Still, those are stickier too. I wonder if it will prematurely kill a smooth fishtail. I use them at times to make u-turns. The car as is sweetly corrects itself in track mode without jarring to a halt and then proceding. Eh? tcoat thoughts?

[Tcoat]

Originally Posted by ~el~jefe~

how would then going to something like a MIchelin pilot ss be then? that's immensely more grippy.

I am not going to get them though, I will be gettin your AS 3+ like you recommended. Still, those are stickier too. I wonder if it will prematurely kill a smooth fishtail. I use them at times to make u-turns. The car as is sweetly corrects itself in track mode without jarring to a halt and then proceding. Eh? tcoat thoughts?

You will be able to do all the same things. It just takes some adjustment as to how you start the process is all. Stay away from really wide tires and the stickiness is manageable with practice.

[~el~jefe~]

Originally Posted by Tcoat

You will be able to do all the same things. It just takes some adjustment as to how you start the process is all. Stay away from really wide tires and the stickiness is manageable with practice.

nice! that is an answer then. Yeah, I am going with the OEM dimensions. I buy in two weeks about those Sotozero pirellis I mentioned to you. It has been incredibly hot in New YOrk for some reason so I delayed it a bit. I am going oem dimensions with the winter performance ones too.

[EndlessAzure]

It's not a scientific study, but I have Michelin PSS 245 on my 17x9 wheels.

In the past, I thought the sport traction was pretty well suited to the stock wheels and tire type (my car was a CPO and came with Toyo Versado Eco tires). After I moved up in tire width and grip, it felt like sport mode traction was kicking in way earlier than what I perceived as the grip limit. This is mostly for spirited driving/canyon however, not purposefully induced slip. This is on a 2014 MY car BTW.

I don't think this makes the car go any slower than on stock wheels/tires; it just means that the difference is greater between what the computer believes the grip limit is versus what the actual grip limit is.

[nikitopo]

Originally Posted by ~el~jefe~

Has anyone come across hard data regarding the interchange between tire grip, friction coefficient, flex, etc, and the pre-programed DSC/Traction control systems in cars like ours?

I wonder about that. it is commonly known that the OEM tires are designed to provide the right grip and slip for the car, and my new 2017 BRZ has a specific system designed now to allow a lot more slip in Track mode. If it came on and was aggressive in its actions, and had aggressively gripping tires non-oem, both with torque control and vector braking, it would underperform, I would think.

I do wonder if anything but the OEM tires actually work with the very dialed in and specific engineering that went into the car.

They changed the DSC/Traction Control Unit in previous BRZ tS cars, so yes the system was dialed for specific tires and grip levels.

[~el~jefe~]

Originally Posted by EndlessAzure

It's not a scientific study, but I have Michelin PSS 245 on my 17x9 wheels.

In the past, I thought the sport traction was pretty well suited to the stock wheels and tire type (my car was a CPO and came with Toyo Versado Eco tires). After I moved up in tire width and grip, it felt like sport mode traction was kicking in way earlier than what I perceived as the grip limit. This is mostly for spirited driving/canyon however, not purposefully induced slip. This is on a 2014 MY car BTW.

I don't think this makes the car go any slower than on stock wheels/tires; it just means that the difference is greater between what the computer believes the grip limit is versus what the actual grip limit is.

You sir, have an insane level of lateral grip. That is way scientific enough for me! Thank you! This actually helps out my decision of which tires to buy. I will go for only a little better grip than oem, but not ultra, and focus on cornering stability (same flex as oem or better) and ride comfort.

This is interesting. I am filling in the gaps of what I wondered for a while.

[Tcoat]

Originally Posted by nikitopo

They changed the DSC/Traction Control Unit in previous BRZ tS cars, so yes the system was dialed for specific tires and grip levels.

They changed traction control for a substantial tire change, suspension change, power change, weight distribution change and probably a couple of things I didn't think of. To say they changed traction control for just the tires is missing the whole picture. You can not separate one thing from the whole package and think it is the sole source of the impact.
The traction control on these cars is dialed in to a very rough level where it will apply equally well across a very wide range of tires not just the normal Primacies.

[mjanmohammad]

Originally Posted by ~el~jefe~

Has anyone come across hard data regarding the interchange between tire grip, friction coefficient, flex, etc, and the pre-programed DSC/Traction control systems in cars like ours?

I wonder about that. it is commonly known that the OEM tires are designed to provide the right grip and slip for the car, and my new 2017 BRZ has a specific system designed now to allow a lot more slip in Track mode. If it came on and was aggressive in its actions, and had aggressively gripping tires non-oem, both with torque control and vector braking, it would underperform, I would think.

I do wonder if anything but the OEM tires actually work with the very dialed in and specific engineering that went into the car.

I doubt its dialed in that specific. I have super grippy RS4 tires on 17x8 wheels and I get the same amount of slip before the track mode kicks in on those and the stock wheels/tires. I think its more related to the yaw/speed sensors

[EndlessAzure]

Originally Posted by mjanmohammad

I doubt its dialed in that specific. I have super grippy RS4 tires on 17x8 wheels and I get the same amount of slip before the track mode kicks in on those and the stock wheels/tires. I think its more related to the yaw/speed sensors

I think a consideration of yaw/speed/accel this is a pretty accurate description of what's going on.

I can pull more lateral G with my grippier tires, but the way I throw the car into the corner can trigger the sport mode TCS

[nikitopo]

Originally Posted by Tcoat

They changed traction control for a substantial tire change, suspension change, power change, weight distribution change and probably a couple of things I didn't think of. To say they changed traction control for just the tires is missing the whole picture. You can not separate one thing from the whole package and think it is the sole source of the impact.
The traction control on these cars is dialed in to a very rough level where it will apply equally well across a very wide range of tires not just the normal Primacies.

They didn't make any changes on power or weight distribution. Tires and suspension should go together anyway with a much gripper setup like the MPSS. I don't know how rough the traction control is dialed, but fact is that they tuned the VDC.
https://www.subaru.co.jp/en/news/arc...e_2_91012.html

Personally I don't care, because I usually take the drive assistance option off. Whenever it was activated it was too abrupt for my tastes and the specific levels of grip. Maybe the track mode in the newer cars is better balanced.

[86 South Africa]

Originally Posted by ~el~jefe~

Has anyone come across hard data regarding the interchange between tire grip, friction coefficient, flex, etc, and the pre-programed DSC/Traction control systems in cars like ours?

I wonder about that. it is commonly known that the OEM tires are designed to provide the right grip and slip for the car, and my new 2017 BRZ has a specific system designed now to allow a lot more slip in Track mode. If it came on and was aggressive in its actions, and had aggressively gripping tires non-oem, both with torque control and vector braking, it would underperform, I would think.

I do wonder if anything but the OEM tires actually work with the very dialed in and specific engineering that went into the car.

So firstly what is the "right amount" of grip?
On the OEM tyres, on a less than ideal road, and in the wet, I've had some (luckily slow speed) slides I wouldn't really want...

So, in that situation the grip sucked and TCS did nothing because it was the slippery road that caused the slide.

In terms of performance related TCS - these are just *aids* and should always be treated as such. Nothing replaces common sense and matching driving speed to conditions, traffic, etc.

That being said I find my TCS actually kicks in too soon when I am feeling playful - so it's "too safe" in this situation. So when I do want to play I simply turn it off completely and put a massive grin on my face with controlled slides I can easily modulate with the throttle and steering.
It's part of the reason I love this car.... so predictable and easy to drive.

[Cole]

Whenever I see any topic relating to the nannies, it always makes me laugh.

How shitty are your driving habits that you have the TC kicking in on a regular enough basis to need to turn it off. Not to mention, at least in the province I live, the kind of driving that would make them kick on, is quite a heavy fine, immediate license suspension and vehicle impound.

And again, public streets and y'all are getting annoyed at the nannies? Think a lot of you need to grow up.