F-Type ( X152 ) 2014 - Onwards
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RWD Owners - how do you go fast but keep straight line wheel spin down?

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  #21  
Old 01-25-2017, 09:54 AM
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Originally Posted by FtypeRRR
i'm sure PSS tires would improve things...would be fun to have slicks to see what that could do. oddly, it does not seem that the AWD improves the 0-60 times much in the magazines (thought it would).
Idk why you say that. The AWD is easily a few tenths better than RWD variants from everything I've done/seen. Not too many people pulling 3.3 zero to 60 in RWDs on the stock tires.
 
  #22  
Old 01-25-2017, 10:44 AM
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Just ordered a set of PSS...
 
  #23  
Old 01-25-2017, 07:52 PM
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Originally Posted by Stohlen
Keep in mind a wider tire does not help the vehicle hook up. But the stickier compound does.
Many of us are curvilinear drivers, and wider tires serve us better.
 
  #24  
Old 01-25-2017, 10:23 PM
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Unfortunately, you won't be able to go nuts with the throttle in a RWD car like this. If you do it controllably - you will just spin rear tires and wag your tail a bit. If you don't do a good job, you will end up on youtube as a part of 'super car wrecks' video.
 
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Old 01-25-2017, 10:25 PM
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Originally Posted by Unhingd
Many of us are curvilinear drivers.
I had it once, doc prescribed an ointment and it eventually went away.
 
  #26  
Old 01-26-2017, 05:01 AM
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Originally Posted by SinF
I had it once, doc prescribed an ointment and it eventually went away.
In my case it's a genetic ailment.
 
  #27  
Old 01-26-2017, 10:08 AM
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Originally Posted by SinF
Unfortunately, you won't be able to go nuts with the throttle in a RWD car like this. If you do it controllably - you will just spin rear tires and wag your tail a bit. If you don't do a good job, you will end up on youtube as a part of 'super car wrecks' video.
Lol.. I'm hooked on those videos..

I've found the ftype to be one of the most controllable high HP RWD cars I've driven. It's very point and shoot, especially when jumping on it going straight. Its always a fun feeling when the back end is still wiggling around and I realize how fast the car is going.

The point being, I never feel out of control in a straight line, just looking for the fastest way to get 0-60 and find that sub 12 sec 1/4.
 
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  #28  
Old 01-26-2017, 10:09 AM
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Originally Posted by Stohlen
Keep in mind a wider tire does not help the vehicle hook up.
Actually, as long as you adjust the tire pressure properly a wider tire absolutely does help the vehicle hook up. ;-)

Dave
 
  #29  
Old 01-26-2017, 02:06 PM
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Originally Posted by DirtyAir
Lol.. I'm hooked on those videos..

I've found the ftype to be one of the most controllable high HP RWD cars I've driven. It's very point and shoot, especially when jumping on it going straight. Its always a fun feeling when the back end is still wiggling around and I realize how fast the car is going.

The point being, I never feel out of control in a straight line, just looking for the fastest way to get 0-60 and find that sub 12 sec 1/4.
I watch those videos as well. I've seen a lot of Corvette and Mustang fails. Most of the videos are guys leaving Cars & Coffee and trying to show out for the crowd. Seeing those videos makes me extra cautious.
 
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Old 01-26-2017, 02:10 PM
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Originally Posted by DPelletier
Actually, as long as you adjust the tire pressure properly a wider tire absolutely does help the vehicle hook up. ;-)

Dave
Not compared to the skinner tire at the same air pressure. Lowering air pressure to increase contact patch applies to all tires, not just wider ones. All factors being equal, a taller tire hooks up better than a wider tire. That's why ice racers have motorcycle sized tires on them.
 
  #31  
Old 01-26-2017, 02:26 PM
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I just saw this F-type tail wagging video on Instagram. I wonder if traction control was off. https://instagram.com/p/BPvCyPyltgj/
 
  #32  
Old 01-26-2017, 02:40 PM
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Originally Posted by HalcyonDays
Did you keep the stock size? Thanks.
I stayed with the stock size for no particular reason.
 
  #33  
Old 01-26-2017, 02:41 PM
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Originally Posted by Stohlen
Not compared to the skinner tire at the same air pressure. Lowering air pressure to increase contact patch applies to all tires, not just wider ones. All factors being equal, a taller tire hooks up better than a wider tire. That's why ice racers have motorcycle sized tires on them.
There is no reason to run the same air pressure though! As long as you have the proper tire pressure for the setup, the wider the tire, the larger the contact patch. period. ....and yes the larger the circumference the larger the contact patch too. That's why drag racers have big azzed tires on them. ;-)

FWIW, the PSS in the stock 295 size has a rim range in the 10" - 11" range and the PSS in 305mm wide has the rim range in the 10.5" - 11.5" range.....as our rims at 10.5" wide, the inference is that the 305 will operate properly (including contact patch) on a 10.5 rim at tire pressures considered in the normal range.

At the end of the day, a 305mm wide tire on an F type WILL have more traction than a 295mm tire as long as the tire pressures have both been optimized for the tire/rim sizes.


Dave
 
  #34  
Old 01-26-2017, 02:44 PM
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Originally Posted by Stohlen
Lowering air pressure to increase contact patch applies to all tires, not just wider ones. .
only to a point, it's possible to lower the tire pressure to the point where you lose traction too.


 
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Old 01-26-2017, 02:45 PM
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  #36  
Old 01-26-2017, 02:48 PM
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the idea is to have the right tire pressure for the tire/rim combo. We used to use chalk to set it up on our 4x4's
 
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Old 01-26-2017, 03:06 PM
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Originally Posted by DPelletier
There is no reason to run the same air pressure though!

Dave
Yes there is, because physics. When you change the width of the tires you aren't affecting the weight of the vehicle or the force of gravity acting on it, so the ideal tire pressure remains largely the same. There are minor factors such as sidewall flex and heat exchange change that make a minor difference, but not more than a small percentage. You can't just drop PSI significantly because you've added 10 mm and call it optimized. By that definition of you went from a 225 at 35 PSI stock tire to a 285 tire, you'd be at 15 psi in the tire and have dreadful traction. The reason airing down tires over factory recommendations works is because they over-inflate for fuel economy purposes and set air pressure for street driving where tires are cooler than when you're on the race track.

Dragsters absolutely have huge meaty tires. But if you look at those, they are almost square... meaning there is as much sidewall height (top and bottom) as there is tread width. The reason for large width in these situations is more for surface inconsistency than anything.

This is the most commonly misunderstood subject in all of the automotive world.
 
  #38  
Old 01-26-2017, 03:06 PM
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This may (or may not) help with the physics question pitting friction vs. grip;

Re: If friction forces don't vary with surf. area, why are race car tires wide?

Cheers,
Dave
 
  #39  
Old 01-26-2017, 03:09 PM
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Originally Posted by Stohlen
Yes there is, because physics. When you change the width of the tires you aren't affecting the weight of the vehicle or the force of gravity acting on it, so the ideal tire pressure remains largely the same. .
No; you need far less pressure the larger the tire gets to carry the same load.

The minor difference between a 295 and 305mm tire on an F type would require only a modest tire pressure adjustment.

Dave
 
  #40  
Old 01-26-2017, 03:18 PM
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.....I will concede that if you are talking about two tires that have the same contact patch, a taller one with a longer contact patch will have more longitudinal grip than a shorter wider one.

I get the physics, I took physics in University too but there is the theory and then there is the practical application. I'd suggest there is a reason that the top automotive engineers keep putting wider and larger tires on their high hp cars to maintain traction.

Dave
 



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