Is your car fast?

[thill]

Originally Posted by fatoni

no. i am aware of that. but when you change the tires of other cars, the same thing happens. i just dont see how this is a point in relation to other cars. that happens for every car. what i am saying, is that when you do that same thing with other cars (lets say a mustang or bmw), the performance gain is smaller for the brz.

LOL, we are talking in circles.. I was responding to this statement that YOU made:

"i dont think the prius tire holds the car back as much as this forum would like to think"

So do you still stand by that via the data I published and you quoted me on?

[fatoni]

Originally Posted by thill

LOL, we are talking in circles.. I was responding to this statement that YOU made:


So do you still stand by that via the data I published and you quoted me on?

i think there are two things going on. its clear you understand what tires will do for the car. that statement youre quoting though still stands. this forum is full of posts talking about changing tires in order to put this car into another class. that statement wasnt directed at you and now i see why we are pretty much arguing for points that the other party might not even disagree with...thats the internet for you.

[KevinBRZ]

1. These aren't Prius tires, they are a different Primacy tire.

2. Keeping the car exactly the same, but with wider tires, makes almost no difference. The weight is distributed the same on any size of tire, so the contact patch will remain virtually identical, just a different shape. If you size the tire properly for the car, then yes, it can make a difference. Just slapping on a 255 tire on a stock BRZ will not help.

[Figo]

FRS MSRP: $25,255
Mustang V6 MSRP: $22,200

Mustang is faster than FR-S at Max Track Speed, 0-60 and track.

Why not buy that? FRS is really slow even with upgraded tires.

Dont tell me that MPG is the only reason.

BTW, I dont think Primacy HP is alot cheaper than Dunlop Star Spec. Primacy HP is not a worse tire. The were just made for different purpose.

Originally Posted by thill

The evidence is right there from the Road And Track link.. Did you not read it? There is a chart at the bottom of the article that has all the data collected for their test. Since you cannot seem to read here is the data for you using the same size tires (stock vs upgrade):


Primacy HP
Size: 215/45-17 87W
Lap Time: 1:29.3
Max Track Speed: 93.6mph
0-60: 6.6
Skidpad: .89g
Slalom: 67.8mph

Dunlop Star Spec:
Size: 215/45-17 87W
Lap Time: 127.0
Max Track Speed: 94mph
0-60: 6.5
Skidpad:.94g
Slalom: 70.2mph

Those are real and tangible differences. No hypothesis needed.

Here is their take:

[Suberman]

Originally Posted by KevinBRZ

1. These aren't Prius tires, they are a different Primacy tire.

2. Keeping the car exactly the same, but with wider tires, makes almost no difference. The weight is distributed the same on any size of tire, so the contact patch will remain virtually identical, just a different shape. If you size the tire properly for the car, then yes, it can make a difference. Just slapping on a 255 tire on a stock BRZ will not help.

Correct. What may help is fitting tires with better tread compound. It would be hard to find tires with a worse tread compound than stock.

Although the stock tire is the HP (high performance? Really?) version of the Primacy its still pretty much a Prius level tire. The Prius actually fits a low rolling resistance version. You definitely don't want those.

[thill]

Originally Posted by Suberman

Correct. What may help is fitting tires with better tread compound. It would be hard to find tires with a worse tread compound than stock.

Although the stock tire is the HP (high performance? Really?) version of the Primacy its still pretty much a Prius level tire. The Prius actually fits a low rolling resistance version. You definitely don't want those.

Primacy HP are considered "luxury performance touring" tires. They are not high performance tires and were never meant for the track.

[PoorMansRacing]

Originally Posted by brzninja

Twins for the wins.

Love it

[DarkSunrise]

Originally Posted by KevinBRZ

2. Keeping the car exactly the same, but with wider tires, makes almost no difference. The weight is distributed the same on any size of tire, so the contact patch will remain virtually identical, just a different shape. If you size the tire properly for the car, then yes, it can make a difference. Just slapping on a 255 tire on a stock BRZ will not help.

Just changing the shape of the contact patch can help increase overall grip. Paul Haney explains it in his book:

For the same vertical load and internal pressure, a tire with a wider tread has a shorter, wider contact patch than a narrower tire. The area of both contact patches is the same if the internal pressure and the load are the same. . . A shorter contact patch at the same slip angle begins to slip at roughly the same distance from the leading edge as with a long contact patch. But the shorter contact patch has more of its length stuck to the road than the longer, narrower contact patch; and therefore a larger portion of its overall area is gripping.

Another explanation I thought was good:

Tires develop their side force because of slip angle (You can think of this as the tread being pulled sideways by the track surface) The contact patch shape will change under cornering, small at the front increasing in size towards the rear. As the force on the tire sideways starts to increase it reaches a point where it exceeds the friction between the tire surface and the road, and the tire beings to slip. As this slip increases, the sideways deflection builds up working the front of the contact patch increasingly hard, while the back starts to slide and lose grip. At some point during this increase you reach the level where more slip angle on the tire means less side force because you are losing more grip at the back than you gain at the front. You hear racers refer to different tires' slip angles all the time. This is what they're talking about. So how does this tie into the static shape of the contact patch between two different size tires?

The longer it is (narrow tire) the more gradually this process will occur. If you shorten it the ramp up to max slip angle will occur more abrubtly but you have more grip. Why? Because less variation in distortion between the front and back contact patches means that more of the contact patch reaches max grip and starts to slide at the same point.

http://www.autocross.us/forums/index.php?showtopic=4410

And then there's also heat dissipation.

Originally Posted by Suberman

Correct. What may help is fitting tires with better tread compound. It would be hard to find tires with a worse tread compound than stock.

Although the stock tire is the HP (high performance? Really?) version of the Primacy its still pretty much a Prius level tire. The Prius actually fits a low rolling resistance version. You definitely don't want those.

The Primacy HP's on our cars are Green X LRR.

Originally Posted by Figo

FRS MSRP: $25,255
Mustang V6 MSRP: $22,200

Mustang is faster than FR-S at Max Track Speed, 0-60 and track.

Why not buy that? FRS is really slow even with upgraded tires.

Dont tell me that MPG is the only reason.

Have you tried driving a Mustang V6? Really disappointing car. I had one for 2 days on gorgeous winding roads in Cal and I could not wait to get back into my FR-S.

[ThisIsChrisKim]

I don't run in the kind of friend circles who are auto enthusiasts (we live in DC where most people don't drive), but none of own a car that's fast. Most of my friends think it's fast when I accelerate in my car since it's faster than their/friends cars (mostly Civics, Corollas, Camrys, etc). The sound probably makes it sound faster, too. (haha)

[BRZfan]

What is "fast" anyway? Try full gallop sometime (at one horsepower). As they say, "It's all relative". Any "mustang' comment not needed.

[ame="http://www.youtube.com/watch?v=O-RzJdfrBis"]Full Speed Gallop (Bareback) - YouTube[/ame]

[uEih]

Originally Posted by doggieboy09

So, for the last 4 months since I have owned this car I have been asked this question a lot by random people. Is your car fast? Or what's the fastest you have been in this car?
How often you you guys asked this question and what is your response?

Haha where are you from exactly? I'm from Sacramento also but I don't get many people stopping me to ask much... Mostly a lot of stares and neck breakers but nobody really approaching me or asking me anything. I got a few compliments and asking how much, etc. but never about specifics. Except maybe one time, a Porsche owner parked near me and couldn't stop looking at my car so I talked to him for a bit. He never said it but he loved how it looked, asked about the engine, etc. he was all about handling, says he bet it handles great. Didn't care too much about the speed like others.

[mortachi]

back to the original topic, waiting for the next person to ask

moron asking: "man, nice car, Is it fast?"

Me: "nope, it just looks that way" deadpan, and I walk away

[Longhorn248]

My car has been slow as shit ever since I took out the flux capacitor.

[BRZfan]

I don't usually find myself around immature yahoos who ask the "fast" question.