The Different between "Gain Grip by Width" & "Gain Grip by Compound"?

[Figo]

I would like to ask everyone here a question.

It's about tire size. Sorry if I bother others.

The question is:

Why people always claim that "a 200hp car do not need meaty tires" or "do not go too wide tires if you do not have enough power";

however, few people claims that"do not go too good tires" or "do not use slick/semi-slick tire because they have too much grip".


So my real question will be: what is the different between "gaining grip by using wide tire" and "gaining grip by using good tire"?


Rolling resistance, that's one of the most frequent words i'v heard when people talked about meaty tires. IMO, the rolling resistance and grip depends on coefficient of friction of tire correct?

Coefficient of friction depends on not only width but also on the tire itself (brand, model) are they?


I know people will talk about weight, but it is an FR-S or a BRZ, not F1. There will not be a day and night difference in 1-2 lb weight.


------------------------------------------------------
let's make an example.

AD08 is a better tire than Hankook V12.
RE11 is also better than Hankook V12.
But V12 is lighter.

18X9.5 good rims: 18lb
255/35R18 V12: 22lb
---->
255 V12 setup: 40lb

18X8.5 good rim: 16lb
225/40R18 AD08: 23lb
---->
225 AD08 setup: 39lb

18X8.5 good rim: 16lb
225/40R18 RE11: 25lb
---->
225 RE11 setup: 41lb



So if people can use a 225 AD08 or RE11 setup for PERFORMANCE, why not 255 V12 setup????

I will have to agree that I'v try meaty tires and they feels slower at 1st and 2nd gear at straight line.

But how about the example above??

They are almost same weight, and similar grip(225 even has more grip than 255).


So I actually made two type of setup above.

1. 255 good tires
2. 225 very good tires.

Let's assume that these two setup has almost the same grip and same weight(as the example shows), will there be any different?

Setup 1 gain grip by width, and setup 2 gain grip by compound.




---------------------------------------------------------------------------------------------------------


If someone say "I am running 225 AD08/RE11 setup", people might think "Thats a nice setup for performance. And good rubber!"

If someone say "I am running 255 V12 setup", people might think "OMG that's too wide, you don have enough power!"





Also, 215(stock size) slick/semi-slick tires should be more gripy than 255 street tires.

Why no one complain about slick/semi-slick tires?


Hope everyone understand my question.

Thank you!


.

[tomkozski]

Don't have any specific facts or figures to back this up, but I'm assuming aerodynamics may be at play here too. Wider tires = more air resistance, especially if they poke out from the fenders (ie, going "flush" with a lower offset). Probably the only time this would have any effect would be during highway driving or high-speed racing (more drag, more fuel burn as engine has to fight more aerodynamic resistance).

Small things like that (ie extra 40mm in tire width) affect the airflow around the twins. For example, on the BRZ, adding the factory spoiler (premium vs. limited model) decreases the coefficient of drag slightly. We have those small vanes on the taillights to improve airflow and decrease drag. Even though the main reason the roof is sculpted is to increase the roof's strength, it's shaped to help airflow. I'm assuming adding wider tires, particularly if they poke out (low offset), will affect the aerodynamics a bit.

[jvincent]

Lots of variable at play, but see if the following makes sense.

- You want your tire to handle the maximum lateral force you are going to apply in turn so that you don't slide and lose speed in the corners. This is a function of tire compound and width. All things being equal, wider is better for grip. Caveat, I'm assuming here that you can get both the wide and skinny tire to their optimal grip temperature.

- At the same time you want the tire to provide the lowest straight line resistance to give you the maximum speed. I'm assuming here that the grip in a straight line is sufficient that you aren't spinning your tires. This is the reverse of the above, i.e. all things being equal, wider is going to be slower.

So, extra tire width is helping you in the corners and hurting you in the straights. Depending on where you drive there will be an optimal width/compound. Unless you are a really, really, good driver, it's more likely that there are a couple of tires that will give you the same performance.

That said, the guys who track heavily have looked at this and concluded that for them the optimum size for the fastest laps is 225 IIRC. Autox may be different.

[Figo]

Originally Posted by tomkozski

Don't have any specific facts or figures to back this up, but I'm assuming aerodynamics may be at play here too. Wider tires = more air resistance, especially if they poke out from the fenders (ie, going "flush" with a lower offset). Probably the only time this would have any effect would be during highway driving or high-speed racing (more drag, more fuel burn as engine has to fight more aerodynamic resistance).

Small things like that (ie extra 40mm in tire width) affect the airflow around the twins. For example, on the BRZ, adding the factory spoiler (premium vs. limited model) decreases the coefficient of drag slightly. We have those small vanes on the taillights to improve airflow and decrease drag. Even though the main reason the roof is sculpted is to increase the roof's strength, it's shaped to help airflow. I'm assuming adding wider tires, particularly if they poke out (low offset), will affect the aerodynamics a bit.

aerodynamics and wide tire……That's the first time I'v heard this.

Probability I am going to make another "225 tire with +30 offset rim" and "255 tire with +40 offset rim setup" example hah.

Anyway thank you, but I dont think that will be the reason...



.

[Figo]

Originally Posted by jvincent

Lots of variable at play, but see if the following makes sense.

- You want your tire to handle the maximum lateral force you are going to apply in turn so that you don't slide and lose speed in the corners. This is a function of tire compound and width. All things being equal, wider is better for grip. Caveat, I'm assuming here that you can get both the wide and skinny tire to their optimal grip temperature.

- At the same time you want the tire to provide the lowest straight line resistance to give you the maximum speed. I'm assuming here that the grip in a straight line is sufficient that you aren't spinning your tires. This is the reverse of the above, i.e. all things being equal, wider is going to be slower.

So, extra tire width is helping you in the corners and hurting you in the straights. Depending on where you drive there will be an optimal width/compound. Unless you are a really, really, good driver, it's more likely that there are a couple of tires that will give you the same performance.

That said, the guys who track heavily have looked at this and concluded that for them the optimum size for the fastest laps is 225 IIRC. Autox may be different.

Thank You.

As you said:

- At corner. Wide tire OR good tire will be better. That's known.

- At straight line, as you said, "extra tire width is helping you in the corners and hurting you in the straights", how about good tire? They will also hurt correct? as you said there is an optimal width/compound. So if you take a look at the example I made above, I actually made two type of setup.

1. 255 good tires
2. 225 very good tires.

Let's assume that these two setup has almost the same grip and same weight(as the example shows), will there be any different? Setup 1 gain grip by width, and setup 2 gain grip by compound.




.

[jvincent]

Originally Posted by Figo

I actually made two type of setup.

1. 255 good tires
2. 225 very good tires.

Let's assume that these two setup has almost the same grip and same weight(as the example shows), will there be any different? Setup 1 gain grip by width, and setup 2 gain grip by compound.

I can really only answer with "it depends".

As an example, you say "almost the same grip". Do you mean cornering grip or rolling resistance? Depending on how hard you are pushing the car can make a big difference.

Also, don't underestimate the importance of temperature when it comes to grip. If you can't get the wider tires warm enough then they probably won't provide their best grip so you could be in a situation where the wider tire is not only slowing you down in the straights but also in the turns.

The only real way to compare the two setups is to actually run them.

[8R6]

why do you say a 255 V12 tire provides similar grip to a 225 RE11? i highly doubt that.

better compound > unnecessary width

but you forgot to factor in tire wear. RE11's (and similar tires) wont last very long on a daily driver. it's overkill and you'll be spending a lot of money on tires for minimal return. running a 225 RE11 will most likely have more grip than a 255 V12 street tire, but the V12 will at least last way longer. and running a 255 V12 will also help provide more grip than a 225 V12. so running a wider "street tire" can get you increased grip (from stock tires), without having to get more race-oriented tires, but still have way better treadlife than running a race-oriented tire.

[Figo]

Originally Posted by jvincent

I can really only answer with "it depends".

As an example, you say "almost the same grip". Do you mean cornering grip or rolling resistance? Depending on how hard you are pushing the car can make a big difference.

Also, don't underestimate the importance of temperature when it comes to grip. If you can't get the wider tires warm enough then they probably won't provide their best grip so you could be in a situation where the wider tire is not only slowing you down in the straights but also in the turns.

The only real way to compare the two setups is to actually run them.

So the more corner grip, the more rolling resistance correct? Cuz rolling resistance is because of the grip of tire.

If the wide tire does not warm up enough it might has less corner grip, but also less resistance correct? So it does not change the question above.. "Is not warm up enough 255 tire = 225/215 good tire?"

So complicated………………

.

[Figo]

Originally Posted by BRGT86

why do you say a 255 V12 tire provides similar grip to a 225 RE11? i highly doubt that.

better compound > unnecessary width

but you forgot to factor in tire wear. RE11's (and similar tires) wont last very long on a daily driver. it's overkill and you'll be spending a lot of money on tires for minimal return. running a 225 RE11 will most likely have more grip than a 255 V12 street tire, but the V12 will at least last way longer. and running a 255 V12 will also help provide more grip than a 225 V12. so running a wider "street tire" can get you increased grip (from stock tires), without having to get more race-oriented tires, but still have way better treadlife than running a race-oriented tire.

better compound > unnecessary width

I agree.

However, that is not the point of the example or of this thread. ALso, it does not change the meaning of my question.

people claim that wide tire is not good because they grip too well and has too much rolling resistance, but never complain about good tires.

SO I was asking why.


As you said 225 RE11 is better than 255 V12.

Then, why no body claim that "Do not run 225 or 215 RE11 (or good tires) because you have only 200hp" instead of "Do not run 255 tires because you have only 200hp"?



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[jvincent]

Originally Posted by Figo

So the more corner grip, the more rolling resistance correct? Cuz rolling resistance is because of the grip of tire.

As you say, it's complicated.

Tread pattern will have an impact on the difference between rolling resistance and lateral grip. Also, the ratio of down to side force is different as well and will have an impact.

I'll still come back and say that the only real way to compare the two setups is to try them.

[rice_classic]

Assuming equal tires and weights and rolling diameters.. A 255 wide tire in an R-Comp is only too much tire if you can't get it hot enough to operate in it's intended heat range.

A 200hp car changing from a 225 to a 255 width tire will have a recordable difference in speed at the end of the longest straight. It might be 1mph, it might be 5 but depending on the layout of the track, the braking will be later (or less), entry speed higher, apex speed and exit speed higher and such the overall lap will *most likely* be lower.

If it was the difference between 205 and 225 then the delta becomes so narrow you'll have to be a damn fine consistent driver with lots of data to see the difference.

Once you start comparing different wheel sizes, heights, compounds, tread blocks, slicks... It all becomes WAY too convoluted to even attempt an answer.

[evolution_sfv]

http://www.tuneruniversity.com/blog/...-size-matters/

A great article

[tahdizzle]

You can get a good look at a steak by sticking your head up a butcher's ass, but wouldn't you rather take the cow's word for it?


Application. application. application.

tire set X vs tire set Y.

In one application, tire set X will out perform Y. But in another application, tire set Y will out perform tire set X.

There is not one combination that will outperform everything in every condition.

[BRZZZZZZZZZZ]

For me, if I hear someone say 225 wide RE-11s and another person say 255 wide V12s side by side with no other info, in my head I think V12 guy wants ok tires with a meaty tread/wheel/look setup, whereas RE-11 guy wants max performance for the width he has chosen.

I am running RS-3s and RE-11s in 225 now and have considered stepping up to 245 or 255 RS-3/RE-11/Z11/PSS but I have a nagging feeling that on stock power I will be disappointed with the extra weight associated of having to go up to a wider 17" wheel plus larger sized tire.