Quote:
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.
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Just changing the shape of the contact patch can help increase overall grip. Paul Haney explains it in his book:
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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.
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Another explanation I thought was good:
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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.
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http://www.autocross.us/forums/index.php?showtopic=4410
And then there's also heat dissipation.
Quote:
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.
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The Primacy HP's on our cars are Green X LRR.
Quote:
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.
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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.