The definition/meaning of over and under steer

[CSLACR]

I've been contemplating the tuning in GT5, and have come to an interesting bit...

Over-steer is when you have to decrease steering angle as speed increases to maintain a line.
Under-steer is when you have to increase steering angle as speed increases to maintain a line.

So in theory, when braking, it would be the opposite, right?
Upon entry in an under-steering car, the decreasing speed would require decreasing steering input to stay on line, and in an over-steering car you would have to increase steering angle as speed decreases.

Thoughts?

 

[DaxCobra]

Is that definition strictly true? I have been in situations where too much lock induces understeer and turning a bit less increases grip levels.

I've just always thought of it as over-rotation and under-rotation.

 

[Adrenaline]

Under and oversteer have to do with pitch, yaw or just a general relation of the rear of the car, in regards to the front of the car. Steering angle has no dictation as far as I know.

 

[CSLACR]

That is the definition exactly.
Consider it on a skid pad, driving an exact circle, then measure steering input as speed rises and falls. More as speed rises = under-steer, less = over-steer.

At least that's how R&T/MT/C&D have defined it that I've seen, I should say.

 

[Adrenaline]

That is the definition exactly.
Consider it on a skid pad, driving an exact circle, then measure steering input as speed rises and falls. More as speed rises = under-steer, less = over-steer.

At least that's how R&T/MT/C&D have defined it that I've seen, I should say.

The definition you've given is the one used by engineers, not by car/motorsport enthusiast.

Regardless, I don't see how the speed increasing or decreasing has an effect on under/oversteer, even in your provided scenario. It's the understeer that dictates the need for more or less steering angle, not whether you're accelerating or decelerating.

 

[CSLACR]

The definition you've given is the one used by engineers, not by car/motorsport enthusiast.

Regardless, I don't see how the speed increasing or decreasing has an effect on under/oversteer, even in your provided scenario. It's the understeer that dictates the need for more or less steering angle, not whether you're accelerating or decelerating.

If you start turning into a corner at 60MPH, holding a line and slow down to 50MPH at the apex in an under-steering car, without changing steering angle from what held your line at 60MPH, where will your car go?

 

[stan0matic]

It's all down to slip angles; the difference between the direction the tread is facing and the direction the tire is headed.
Say you've got ten points for grip, 10 for the front, 10 for the back. At higher numbers, we have higher slip angles. If you have 8 points on the back, and 10 on the front you have understeer. And vice versa.

In the OP example, we have braking on the back, and braking and steering on the front. The weight transfer to the front under brakes theoretically means there is more traction to go round, but say we are using 5 points for braking and 5 points for steering (lateral Gs), we are maxed out. At the back all that is happening is a bit of braking and some lateral, say 3 and 3, so the front is running higher slip angles and the car understeers.
Say you yank on the handbrake on this same corner, the available points for braking go thru the roof, (10+) there is none available for lateral and you have massive oversteer.
In some tunes, I put considerably more braking on the rear, in order to provoke some oversteer to tuck the nose in when entering a corner. GT5 seems to have more understeer than when I first started playing, but maybe I am just going faster.

 

[Adrenaline]

If you start turning into a corner at 60MPH, holding a line and slow down to 50MPH at the apex in an under-steering car, without changing steering angle from what held your line at 60MPH, where will your car go?

You're distorting the definition to suit your needs.

If steering angle remains a constant, understeer and oversteer occur based on speed alone. So in your scenario the car would 'oversteer' because at 50mph, the car is now turning a tighter radius than needed. And since you're 'over steering' you now need to 'decrease' steering angle. The definition doesn't change.

 

[XDesperado67]

Okay I'm not the brightest guy around by a long shot but I'm a little confused here.
If I have a car on a skid pad and I'm driving in a circle at 30mph that stays the same diameter, I can see how speeding up could cause the circle to get larger as the front end started to lose traction. But I can't see how the circle would get smaller without changing the steering angle. Higher speed could cause either the front or rear to start losing grip requiring the driver to change the steering angle to maintain the same diameter circle but as long as both ends maintain a consistent level of grip in relation to each other shouldn't the circle stay the same?

I've always viewed oversteer as a condition where the front has significantly more grip than the rear causing the car to rotate faster than desired, while understeer was the front having less grip than the rear causing less rotation than desired. Am I wrong?

 

[Motor City Hami]

I've always viewed oversteer as a condition where the front has significantly more grip than the rear causing the car to rotate faster than desired, while understeer was the front having less grip than the rear causing less rotation than desired. Am I wrong?

^ Bingo. Oversteer/understeer is about front/rear grip levels. Steering input is one of the long list of items that may or may not help solve the grip problem.

 

[Johnnypenso]

Okay I'm not the brightest guy around by a long shot but I'm a little confused here.
If I have a car on a skid pad and I'm driving in a circle at 30mph that stays the same diameter, I can see how speeding up could cause the circle to get larger as the front end started to lose traction. But I can't see how the circle would get smaller without changing the steering angle. Higher speed could cause either the front or rear to start losing grip requiring the driver to change the steering angle to maintain the same diameter circle but as long as both ends maintain a consistent level of grip in relation to each other shouldn't the circle stay the same?

I've always viewed oversteer as a condition where the front has significantly more grip than the rear causing the car to rotate faster than desired, while understeer was the front having less grip than the rear causing less rotation than desired. Am I wrong?

I agree...you're not the brightest guy around...lol...just kidding.. There may be a technical definition that's more complicated than the one you gave, but that's how I view it, as basically an imablance between front and rear grip that changes depending on lateral g's, weight shift etc.

 

[stan0matic]

Over-steer is when you have to decrease steering angle as speed increases to maintain a line.
Under-steer is when you have to increase steering angle as speed increases to maintain a line.

So in theory, when braking, it would be the opposite, right?

Aha! Having closely re-read the OP, may I point out a slip in logic.
The assumption here is that braking is the opposite of accelerating. Not so!
As far as the tire (chassis, etc) is concerned, it is all load.
Hope that helps.

 

[CSLACR]

You're distorting the definition to suit your needs.

If steering angle remains a constant, understeer and oversteer occur based on speed alone. So in your scenario the car would 'oversteer' because at 50mph, the car is now turning a tighter radius than needed. And since you're 'over steering' you now need to 'decrease' steering angle. The definition doesn't change.

How so?

@ - The rest: I don't want to debate individuals personal definitions of over or under-steer.
The prime semantic you can't avoid there is driver error. A drivers **** up doesn't mean a car is "over-steering" and the "definitions" above this aren't so hot at distinguishing the difference. In fact, they can't do that at all.

 

[Adrenaline]

How so?

With the second part of my post that you quoted.
Your example, still follows the definitions that you provided. I'm confused as to where you think things go backwards?

 

[CSLACR]

With the second part of my post that you quoted.
Your example, still follows the definitions that you provided. I'm confused as to where you think things go backwards?

So I'm distorting it by being right?

If a car requires more steering angle to maintain a line as speed increases, would you also have to decrease the steering angle as the speed decreases?
Sounds like a simple enough question, and 100% distortion-free if you ask me...

Since that answer is a resounding and happy "yes", I'll continue...

By this "used" definition:

I've always viewed oversteer as a condition where the front has significantly more grip than the rear causing the car to rotate faster than desired, while understeer was the front having less grip than the rear causing less rotation than desired. Am I wrong?

Any car that under-steers could be defined as over-steering on entry and under-steering on exit.
Any car that over-steers could be defined as under-steering on entry and over-steering on exit.

Not only is this where I was headed, but it also points out the huge potential flaws in relating "over-steer" with "the rear slid out".
And it has to do with every tuning discussion we've ever had, any and all of us.

 

[Adrenaline]

So I'm distorting it by being right?

If a car requires more steering angle to maintain a line as speed increases, would you also have to decrease the steering angle as the speed decreases?
Sounds like a simple enough question, and 100% distortion-free if you ask me...

Since that answer is a resounding and happy "yes", I'll continue...

By this "used" definition:

Any car that under-steers could be defined as over-steering on entry and under-steering on exit.
Any car that over-steers could be defined as under-steering on entry and over-steering on exit.

Not only is this where I was headed, but it also points out the huge potential flaws in relating "over-steer" with "the rear slid out".
And it has to do with every tuning discussion we've ever had, any and all of us.

Sorry buddy... You aren't making sense.
Regardless of the scenario you give, steering angle and its relation to under or oversteer will remain constant.

Any car can understeer and oversteer at different parts of a track, but that's based, again, on steering angle, by your definition, not by whether the car is entering, exiting, accelerating or decelerating.

So, if you feel that I'm completely misunderstanding you, then please, give a detailed example, of what you're trying to portray, so that I can follow along, because at the current time, you're saying all the correct things, and then you appear (to me) to be adding a completely backward 'conclusion' at the end of it, which doesn't follow the rest of what you just said.

 

[CSLACR]

Because in an over-steering car, you steer more (turn the wheel farther) at slower speeds than higher speeds.
As you're driving into a corner, the nature of this would result in the sensation of "under-steer" by definition. You would have to steer more to achieve the same result the slower your speed dropped.

In an under-steering car, you'd have to steer into the corner, but as speed drops the same steering angle would become too much due to the lower speed, and you'd have to dial the steering back to maintain a line. Dialing the steering back to maintain a line is generally considered a characteristic of over-steer.

 

[Adrenaline]

Because in an over-steering car, you steer more (turn the wheel farther) at slower speeds than higher speeds.
As you're driving into a corner, the nature of this would result in the sensation of "under-steer" by definition. You would have to steer more to achieve the same result the slower your speed dropped.

In an under-steering car, you'd have to steer into the corner, but as speed drops the same steering angle would become too much due to the lower speed, and you'd have to dial the steering back to maintain a line. Dialing the steering back to maintain a line is generally considered a characteristic of over-steer.

You're distorting comparison speeds.

So, I'm going to isolate the actual question, without speeds taken into account, because speed is irrelevant, the car either needs more or less steering angle, period. If it needs more, it's understeer, if it needs less, it's oversteer.

Because in an over-steering car, you steer more (turn the wheel farther) at slower speeds than higher speeds.

First: No. In an oversteering car, you steer less. (turn the wheel the opposite direction)
Second: Speed here is irrelevant, at any given speed, the car either requires more or less steering angle. If you're going slower, it requires less steering angle, than if you were going faster, but you can't compare 2 separate speed scenarios, because that's not how the over or understeer is decided. It's decided by your current speed, and current need.

Counter arguement.
Car at 50mph requires 18* of steering angle
Car at 60mph requires 20* of steering angle.

Based on the above, you can NOT accurately say that the car at 60mph is 'understeering' simply because it requires more steering angle.

You can only compare 2 steering angles at the same rate of speed.
Does that make sense?

In an under-steering car, you'd have to steer into the corner, but as speed drops the same steering angle would become too much due to the lower speed, and you'd have to dial the steering back to maintain a line. Dialing the steering back to maintain a line is generally considered a characteristic of over-steer.

In a scenario where you require LESS steering angle, (whether due to decreasing speed or otherwise) the car is no longer classified as understeering.

You can't universally say a car is understeering, and then say that if it oversteers at any speed, the definition of understeer is backwards.

 

[CSLACR]

I'm not questioning the definition, I'm talking about the impression it can leave off. I'm also talking about how the two can be misconstrued.

I'm also not sure you're completely understanding my point, which isn't that over-steering cars must under-steer on entry, but that the nature of under-steer and how it works can lead to a false impression.
People taking into account their own interpretations to generally define over-steer as any time the rear steps out just opens another big can of worms. Most notably that one drivers "over-steer" is another drivers "under-steer", which leaves a blank on how the car actually behaves.

 

[Adrenaline]

I'm also not sure you're completely understanding my point, which isn't that over-steering cars must under-steer on entry, but that the nature of under-steer and how it works can lead to a false impression.
People taking into account their own interpretations to generally define over-steer as any time the rear steps out just opens another big can of worms. Most notably that one drivers "over-steer" is another drivers "under-steer", which leaves a blank on how the car actually behaves.

Whether due to a lack of comprehension or not, I must sadly say I disagree with you on this.
Can you give me an example of the rear of the car 'stepping out' that can be construed as anything but oversteer? I'm sure there might be an example, but I can't think of any right now, nor can I think of any situation where one mans oversteer, is anyone elses understeer.

 

[CSLACR]

Whether due to a lack of comprehension or not, I must sadly say I disagree with you on this.
Can you give me an example of the rear of the car 'stepping out' that can be construed as anything but oversteer? I'm sure there might be an example, but I can't think of any right now

It would be most likely under-steer causing the sensation of over-steer, if anything.

I find it most ironic that 99.9% of tunes made for cars in GT5 "over-steer" on entry and "under-steer" on exit too.
To call me crazy for saying they're related would be a reach imo.

nor can I think of any situation where one mans oversteer, is anyone elses understeer.

Really?
You can't think of a single car/tune that's too "loose" for some drivers yet too tight for others? I suppose it could be that you haven't been around drivers that tune with alien speed enough to see exactly how loose of a car can be called "an under-steering pig".

 

[MrGrado]

There are tunes that would generally understeer but could have the rear step out over a gentle crest in a high speed corner for example. As the rear step out, the car is oversteering for sure, but not because the car has any natural tendancy to oversteer.

And yeah, some people tune a car and claim it is crazy oversteery and will kill the driver, but when I drive it, I'm faster than the tuner and I do not have to counter steer anywhere. Rather the opposite, I'm wanting more grip at the front of the car so I can go even faster. Definitely one mans oversteer is someone elses understeer.

 

[Adrenaline]

It would be most likely under-steer causing the sensation of over-steer, if anything.

I find it most ironic that 99.9% of tunes made for cars in GT5 "over-steer" on entry and "under-steer" on exit too.
To call me crazy for saying they're related would be a reach imo.


Really?
You can't think of a single car/tune that's too "loose" for some drivers yet too tight for others? I suppose it could be that you haven't been around drivers that tune with alien speed enough to see exactly how loose of a car can be called "an under-steering pig".

If you're defining a 'snap-oversteer' caused by an excess understeer, then a sudden grip in the front tires which cases the rear to 'snap' as classified, then I still classify that as understeer, to the extreme of causing a false oversteer condition.

If we're defining a car, that has different characteristics in different parts of a corner, then I have no argument that a car can understeer and oversteer, but not at the same time, and it doesn't change, and I don't think that's what you were initially speaking of.

If what you meant was that one mans 'understeering tune' is another mans 'oversteering car' then I can agree with that. But understeer, the actual act of understeering, is never someone elses oversteer(by definition). It's one or the other, is what I was getting at.

 

[hhhaaa]

Hi, I have just finished reading the first page of this forum and no one did mention about the weight balance has an effect on under or over steer too, In my opinion I think there are more issues involve to get a perfect balanced car for an easy and smooth turning without loosing maximum speed, I use to have more than few cars in my garage before all this recent up-dates, but now honestly I don't even have one 👎

 

[Motor City Hami]

Like Adrenaline, I too do not fully understand what CSLACR is trying to describe. If I am comprehending correctly, he’s saying that oversteer and understeer are all defined and directly related to steering angle input? I can think of plenty of real world and in-game situations where the car has understeer at a certain speed and no more or no less steering input is going to make the car turn more. If you are to the point of the front tires losing grip, then you have two choices; slow down until the front tires are back to within their grip limit or change the car setup to rebalance front/rear grip. If already past the grip limit of the front tires, more steering input will just lead to more plowing of the front wheels. I’ve been in real world situations during my more rookie seasons and all this does is overheat front tires, causing them to grain and wear out faster. In the game this can be seen when using a wheel and the outside front tire starts to turn red. More steering input just turns it redder and produces tire smoke. Carrying trail braking a bit further can help a little, but beyond that, there is little more that the driver can do to get that car through the corner more quickly – a setup change is required.

I can’t subscribe to redefining oversteer and understeer. Yes, some drivers will describe a car differently, but I believe that has more to do with their ability and driving style than the car. The car’s setup can produce the same front/rear grip with each driver. I don’t have my own definition of oversteer and understeer. I use the definition from the master, Carol Smith. From Tune to Win, chapter 11, Understeer, Oversteer, Stability and Response, “Understeer and oversteer can be explained in terms of relative front and rear tire slip angles, in terms of tire thrusts about the vehicle’s center of gravity and/or in terms of tire force vectors with respect to turn centers.” Or a more simplified description, “… it becomes a very simple question of whether the front tires reach their limit of cornering traction before or after the rear tires do.” Understeer, “The driver has to slow the car in order to regain steering control and, should he succeed in doing so before he hits something, will come in and complain about excessive understeer.” Oversteer, “… if the rears break loose first, the car tries to spin and the driver applies opposite steering lock and either backs off the throttle or adds power depending on circumstances and driver characteristics. He then bitches about oversteer…”

CSLACR, I think your thoughts on steering angle can be a symptom or a potential solution to oversteer/understeer, but it doesn’t compute to me that it is the definition of each.

 

[CSLACR]

If you're defining a 'snap-oversteer' caused by an excess understeer, then a sudden grip in the front tires which cases the rear to 'snap' as classified, then I still classify that as understeer, to the extreme of causing a false oversteer condition.

If we're defining a car, that has different characteristics in different parts of a corner, then I have no argument that a car can understeer and oversteer, but not at the same time, and it doesn't change, and I don't think that's what you were initially speaking of.

If what you meant was that one mans 'understeering tune' is another mans 'oversteering car' then I can agree with that. But understeer, the actual act of understeering, is never someone elses oversteer(by definition). It's one or the other, is what I was getting at.

If you're looking for an exact purpose of creating the thread, it's this discussion in general, nothing more.

I have a theory that under-steer and over-steer can and do get mixed up based on many things, most notably driver input.
Another would be under-steering cars giving an impression of being neutral or even loose on entry.


As said, 2 drivers in the same car with the same tune will experience different worlds.
How can we agree what spring rate changes do if we're using different definitions or preferences for descriptions?

“… it becomes a very simple question of whether the front tires reach their limit of cornering traction before or after the rear tires do.”

In real life you don't have drivers 5 seconds a lap back on a 1.5 mile tracks spinning out like tops, while others complain about under-steer. (from an identical car/tune)

If I had a nickel for every car that under-steered on exit I tested in a shootout... And yet they over-steer for other drivers.

So are they under-steering or over-steering?

The variables this all throws into tuning discussions about what changes do what, absolutely blows my mind. I could go into specifics I guess...

 

[XDesperado67]

I think a lot of your issue here CSLACR is actually with the drivers and their relative skill levels and not with the cars so much.

I've tuned a number of cars that I felt had good handling and for me felt like they were about as loose and oversteering as I could manage. Yet handed over to more skilled drivers such as yourself and mike_gt3 was told they were a bit tight and tended to understeer. Conversely I have had cars others complained about being understeering pigs that when driven correctly handled just fine. The Enzo is a good example of the later situation. A lot of people complain it has horrible understeer, but for most of them it's a case of bad driving and not the car. Take any car into a corner to hot and your liable to get understeer, brake appropriately and enter corners at reasonable speed and the car will be fine. The better the driver the more consistent they will be in hitting those perfect brake points, turn in points and speeds to get the most from a car.

 

[CSLACR]

I think a lot of your issue here CSLACR is actually with the drivers and their relative skill levels and not with the cars so much.

I've tuned a number of cars that I felt had good handling and for me felt like they were about as loose and oversteering as I could manage. Yet handed over to more skilled drivers such as yourself and mike_gt3 was told they were a bit tight and tended to understeer. Conversely I have had cars others complained about being understeering pigs that when driven correctly handled just fine. The Enzo is a good example of the later situation. A lot of people complain it has horrible understeer, but for most of them it's a case of bad driving and not the car. Take any car into a corner to hot and your liable to get understeer, brake appropriately and enter corners at reasonable speed and the car will be fine. The better the driver the more consistent they will be in hitting those perfect brake points, turn in points and speeds to get the most from a car.

I can change the example to GTAcademy finalist R1600Turbo and GTAcademy almost-finalist outlaw4rc.

R1600Turbo prefers tighter more under-steery cars than pretty much any D1 driver I know.
outlaw4rc prefers looser cars than most non-D1G drivers I know.

But it's not about preference, it's about definition, so when R1600 drops a comment on a car being too "loose" it actually translates to "great" for the rest of us.

Surely we can see how this leaves a blank on how the car actually performs, yet the drivers are relatively identical in terms of both pace and consistency.

 

[Motor City Hami]

@CSLACR - One flaw in your logic. Our tunes are NOT the exact same car for two different drivers. Same settings on the screen, yes, but each of us is using a different input device. R1600 uses a DFGT with bungies on the brake pedal. His FFB settings are also a factor. DS3 users like different levels of controller sensativity and many use custom button settings. I have added stick extenders to my DS3 which changes the feel of the normal DS3 sticks. My G27 has a Nixim brake mod and I like FFB set really low (because I think the programming is really artificial).

Just because people have different driving styles and use different input devices does not mean that we need to redefine the meaning of understeer and oversteer.

Real world is no different. I like a semi-loose car. Many of the other regional level competors will say that my car is too loose. Yet, many of the national level racers will say that my set up is a little conservative.

 

[CSLACR]

@CSLACR - One flaw in your logic. Our tunes are NOT the exact same car for two different drivers. Same settings on the screen, yes, but each of us is using a different input device. R1600 uses a DFGT with bungies on the brake pedal. His FFB settings are also a factor. DS3 users like different levels of controller sensativity and many use custom button settings. I have added stick extenders to my DS3 which changes the feel of the normal DS3 sticks. My G27 has a Nixim brake mod and I like FFB set really low (because I think the programming is really artificial).

Just because people have different driving styles and use different input devices does not mean that we need to redefine the meaning of understeer and oversteer.

Real world is no different. I like a semi-loose car. Many of the other regional level competors will say that my car is too loose. Yet, many of the national level racers will say that my set up is a little conservative.

Oh, redefining it would be not my method.

The actual definition I posted in the OP. Anything else is slang and driver-dependent.

You can skip the rest if you like, I've come to the determination that everyone really prefers to base it on their own preference rather than the actual characteristics of the vehicle. 👍

Just keep a mental note if CSLACR says "over-steer" or "under-steer" he means the car, not "for him".



I went from DS3, to DFGT to DFGT w bungees to the Fanatec GT3RS +CSR Elites.
Didn't change a thing. None of them. Every time I test a tune to this day with a DS3, my preference is exactly the same as it is with the wheel(s).
And I would strongly disagree that FFB levels change under-over-steer for drivers.
I tried the following settings for FFB, none of which affected over or under-steer in any way:
Unplugged - 1,2,3,4,5,6,7,8,9,10 - DFGT
1,2,3,4,5,6,7,8,9,10 + 1-10 on the Fanatec (a lot of combos) + the constant FFB on the Fanatec(not on other wheels)

I could also point to the GTAcademy finalists, such as R1600Turbo (yeah he did it with a DS3) and I recall a "Spud" something in the WRS that was D1G with a DS3. Dholland, and pretty much everyone who was an alien before GT5 is also just as good on the DS3. Remy_K was the WSGTC 2 winner using a DS3, and Litchi drives without ABS regularly with a DS3.

Long story short I don't actually think controller choice has much effect at all.