Autocross Tire Pressures, books
#11
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Originally Posted by Orthonormal,Aug 5 2010, 05:51 AM
One thing I don't do any more is use a pyrometer. The last time I used it, it showed the center of the tire as being cooler than the edges even after adding over 10psi to the tires and slowing down my times about 2 seconds!
Josh - I wouldn't worry too much about trying to get the "perfect" tire pressure. Andy Hollis, for all his GRM(and personal) tire testing, puts his tires at a base pressure in grid, and doesn't touch them the rest of the heat. Everyone obsessing over 1-2 psi is well into the realm of diminishing returns IMO. If you are going to make a tire pressure change, make it a big one(5psi min). I ran everywhere from 40psi to 33psi on my Hankooks, and it wasn't until I got down to 33psi that I actually noticed a difference in feel or speed.
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Originally Posted by alvanderp,Aug 5 2010, 10:57 AM
Pyrometers(even probe style ones) are barely useful after a drive back to your grid spot. They can give you an idea of how the tire is being used, but it's a vague idea. Unless you have someone sticking the probe in right after you come through the lights, the data can be dubious.
Josh - I wouldn't worry too much about trying to get the "perfect" tire pressure. Andy Hollis, for all his GRM(and personal) tire testing, puts his tires at a base pressure in grid, and doesn't touch them the rest of the heat. Everyone obsessing over 1-2 psi is well into the realm of diminishing returns IMO. If you are going to make a tire pressure change, make it a big one(5psi min). I ran everywhere from 40psi to 33psi on my Hankooks, and it wasn't until I got down to 33psi that I actually noticed a difference in feel or speed.
Josh - I wouldn't worry too much about trying to get the "perfect" tire pressure. Andy Hollis, for all his GRM(and personal) tire testing, puts his tires at a base pressure in grid, and doesn't touch them the rest of the heat. Everyone obsessing over 1-2 psi is well into the realm of diminishing returns IMO. If you are going to make a tire pressure change, make it a big one(5psi min). I ran everywhere from 40psi to 33psi on my Hankooks, and it wasn't until I got down to 33psi that I actually noticed a difference in feel or speed.
#13
I really like 33psi with the Kooks and notice a difference in rear bite from 36psi. The problem is that uneven wear start to occur when you dip into the mid-lower 30psi range. All this is on my B-Stock setup. Im sure suspensions changes will help.
-Marc
-Marc
#14
I would also read this...
Autocross to Win eBook (online free)
This book is a must and is similar to what is emphasized in the Evolution School Phase 2 (visualization). It's great for everything from conditioning reactions for a mis-shift to steering techniques to driving/improving during a race.
Inner Speed Secrets: Mental Strategies to Maximize Your Racing Performance by Ross Bently
Currently running 38 F and 35 R on the Kooks. The wear has been good and the temperatures reasonably (within 10 deg) even across the tire (-2.2 deg camber front and -2.3 deg rear). The pyrometer is really good for maintaining the temperature of the tires which seem to be happiest between 150-160F.
Autocross to Win eBook (online free)
This book is a must and is similar to what is emphasized in the Evolution School Phase 2 (visualization). It's great for everything from conditioning reactions for a mis-shift to steering techniques to driving/improving during a race.
Inner Speed Secrets: Mental Strategies to Maximize Your Racing Performance by Ross Bently
Currently running 38 F and 35 R on the Kooks. The wear has been good and the temperatures reasonably (within 10 deg) even across the tire (-2.2 deg camber front and -2.3 deg rear). The pyrometer is really good for maintaining the temperature of the tires which seem to be happiest between 150-160F.
#15
But I was told by some SCCA old timers that the chalk technique doesn't really work well for today's low profile street tires because the sidewalls are so stiff, tire pressure changes don't make much of a difference in rollover onto the sidewall. Also, that tires are so different in terms of wear the "tread" stops on the edge as well.
#16
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Originally Posted by davidc1,Aug 15 2010, 08:38 AM
I was told by some SCCA old timers that the chalk technique doesn't really work well for today's low profile street tires
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Originally Posted by davidc1,Aug 15 2010, 10:38 AM
But I was told by some SCCA old timers that the chalk technique doesn't really work well for today's low profile street tires because the sidewalls are so stiff, tire pressure changes don't make much of a difference in rollover onto the sidewall. Also, that tires are so different in terms of wear the "tread" stops on the edge as well.
#18
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Originally Posted by josh7owens,Aug 15 2010, 06:27 PM
then whats your method? even pressures across tire?
I ass-u-me you mean temps...
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Originally Posted by jguerdat,Aug 16 2010, 07:59 AM
I sure hope so. Uneven pressures across the tire would be a REAL problem.
I ass-u-me you mean temps...
I ass-u-me you mean temps...
#20
Originally Posted by josh7owens,Aug 15 2010, 03:27 PM
then whats your method? even pressures across tire?
Mainly, I try to keep the rears lower than the front to decrease my chances of looping the car, but towards the end of the day, in these real hot SoCal temps, my fronts start getting too hot and I get understeer.
Someone said I should get a CR front sway bar...?
Any advice?