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> Tire pressures, autox
r_towle
post May 31 2008, 07:39 PM
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What is the best starting pressure for autox
205/50 15 Khumo V710

Gotta run tommorow, so please give advice.

Rich
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SirAndy
post May 31 2008, 07:49 PM
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QUOTE(r_towle @ May 31 2008, 05:39 PM) *

What is the best starting pressure for autox
205/50 15 Khumo V710

Gotta run tommorow, so please give advice.


what does khumo recommend? i'd say, start somewhere in the low/mid 30s and see how that feels and adjust accordingly ...
(IMG:style_emoticons/default/shades.gif) Andy
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r_towle
post May 31 2008, 07:52 PM
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did that last season...they get really greasy if you start at the Khumo pressures...they end up in the 40's after one run...

Just looking for a few guys that are running these to see what everyone else likes to do...we ended last year at 26lbs all around when cold...

Rich
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plas76targa
post May 31 2008, 08:21 PM
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Rich, I have Kumho's that are the 205/50's ..forgive me not sure if they are the V710's. I ran the last two AutoX's here with them in the hight 30's - 36-38. The chalk lines wore off really close to the shoulder's. I'm still a novice in the AX arena but I hope this helps.
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mskala
post May 31 2008, 09:35 PM
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I've reduced the pressure over the last few years, our cars are light and you want to have a good sized contact patch. I've gone down to ~28, keeping them there by just letting out air every run if necessary. This may be different using the 5.5" rims you have. I have 7" rims and am using 215/40/16 V710's, so my sidewalls are also smaller.
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Borderline
post May 31 2008, 10:02 PM
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Depending on your suspension setup, I've had 24/26 recommended to me and with the way my car has been lightened, I've run as low as 20/25!!!

Kumho's recommendation of low 30's is for cars that weigh 500-1000 lbs heavier than ours!

Have fun!
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PeeGreen 914
post May 31 2008, 10:22 PM
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I am running 225/50s at 27lbs. They feel good from start to finish.
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plas76targa
post Jun 2 2008, 07:00 AM
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Wow, after reading these replies I may try less than the 36-38 I've been running.

Rich - curious, what did you end up trying over the weekend and how did you do?
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Joe Ricard
post Jun 2 2008, 07:26 AM
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26 cold seems to be about right as I try to maintain 30 hot. Tire pyrometer readings over 110 are considered warming up.

I usually see pressures raise about 3 to 4 degrees per run till they stabilize at a temp.
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PeeGreen 914
post Jun 2 2008, 11:50 AM
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QUOTE(Joe Ricard @ Jun 2 2008, 06:26 AM) *

26 cold seems to be about right as I try to maintain 30 hot. Tire pyrometer readings over 110 are considered warming up.

I usually see pressures raise about 3 to 4 degrees per run till they stabilize at a temp.

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r_towle
post Jun 2 2008, 11:57 AM
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we ran 26 cold.
Never touched them...not my idea of fun.

We will go up a few pounds in the rear to allow a bit more sliding.

Rich
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PeeGreen 914
post Jun 2 2008, 12:03 PM
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You didn't get any heat in them?

You shouldn't be sliding. If you are the tires have too much or too little air.
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J P Stein
post Jun 2 2008, 12:18 PM
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QUOTE(Phoenix 914-6GT @ Jun 2 2008, 11:03 AM) *

You didn't get any heat in them?

You shouldn't be sliding. If you are the tires have too much or too little air.


If you're not sliding, you ain't tryin' hard enuff. (IMG:style_emoticons/default/biggrin.gif)
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PeeGreen 914
post Jun 2 2008, 12:23 PM
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(IMG:style_emoticons/default/av-943.gif) Maybe that's wht Britan Is faster (IMG:style_emoticons/default/blink.gif)
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PeeGreen 914
post Jun 2 2008, 05:10 PM
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So I talked with a fellow teener who AXs with me who is running the same tires you are. His car feels very nice on the track and he is running 31 and 33.
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r_towle
post Jun 2 2008, 06:07 PM
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track and autox are different animals..

Sliding the rear end in tight chicago boxes has a certain advantage...
We are close...we will tune it in over time.

Rich
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PeeGreen 914
post Jun 2 2008, 06:21 PM
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QUOTE(r_towle @ Jun 2 2008, 05:07 PM) *

track and autox are different animals..

Sliding the rear end in tight chicago boxes has a certain advantage...
We are close...we will tune it in over time.

Rich


I still disagree, but what do I knw... My times are slow. (IMG:style_emoticons/default/unsure.gif)
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r_towle
post Jun 2 2008, 06:29 PM
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tires dont heat up as much during a 1 minute autox versus a 20 track session.
The turns at an autox are much more severe versus a sweeping turn at a track....

I would prefer more tire pressure at the track and less at an autox.

The sliding can be controlled once we get the pressures perfect.
these autox setups favor the 911's typically, so there are long high speed sections, and turns that work best of you can swign the ass of the car around and then stand on the gas...like a 911.
In the 914 the car tends to bod down if you loose to much speed, so a bit of sliding helps keep the speed up.

We were less than a second behind the winner of the class, so we are close...there was a bit of push and with the whole new suspension, new tires, new steering rack, new front bar etc etc...its just fine tuning now...but we will win this year...
Rich
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PeeGreen 914
post Jun 2 2008, 06:38 PM
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You need to come out here for some good AXs. Ours are designed by a teener but still keeps it good for the momentum cars like the 914. I've never had the priveledge of taking my car to the track, but I AX regularly. So does the guy that I gave you his tire pressures. I think the part I am sidagreeing with is your term sliding. If by that you mean drift I would agree as when you are exiting a box your car with drift out a little, but you do want to avoid that as much as possible as it slows you down. If you ever find yourself out in our area and we have an AX you are always welscome to codrive my car (IMG:style_emoticons/default/biggrin.gif) I welcome all tire warmers (IMG:style_emoticons/default/wink.gif)

So on another note... my tires raise about three to four degrees on the first run... did this not happen to you? It should have unkess it was really cold out or rainy out.
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J P Stein
post Jun 2 2008, 07:06 PM
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QUOTE(Phoenix 914-6GT @ Jun 2 2008, 05:38 PM) *

If you ever find yourself out in our area and we have an AX you are always welscome to codrive my car (IMG:style_emoticons/default/biggrin.gif) I welcome all tire warmers (IMG:style_emoticons/default/wink.gif)

So on another note... my tires raise about three to four degrees on the first run... did this not happen to you? It should have unkess it was really cold out or rainy out.


Come July 5 (weather permitting) we can swap rides.....also assuming there is sufficient time. (IMG:style_emoticons/default/biggrin.gif)

My tires gain 3-6 lbs pressure every 2 runs, assuming normal ambient temps.
Usually this subsides after 3-4 of such cycles then holds constant. Brit & I drive very much the same....he just goes a little faster everywhere....about 2 sec quicker on a 60 sec course.

Booting the back end around a particular cone is acceptable practice in my book.
The LSD makes that much more controllable.
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