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nolift914
I am running Goodyear 430 compound slicks for the first time in an autocross, looking for a good starting point for the cold tire pressures. I have been running Nitto NT-01's for the last few years which preform well at 40psi hot and 37psi cold. Are bias ply slicks different in the baseline psi.
SirAndy
The 430 are too hard for AX, IMHO. I'm running the 250 which are the softest GY you can get and even those never get up to temp.
In my experience, they work better with much lower pressures than one would usually run.

I've tried everything from high 30s down to 15. Depending on the surface and ambient temps, i found the sweet spot for me to be in the low 20s.
The car will feel weird with that low of a tire pressure but actually stick better. Once you get used to the odd feeling.

Try starting out in the low 30s and go down during the day and see what that does for your times ...
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nolift914
QUOTE(SirAndy @ Jun 12 2013, 11:25 AM) *

The 430 are too hard for AX, IMHO. I'm running the 250 which are the softest GY you can get and even those never get up to temp.
In my experience, they work better with much lower pressures than one would usually run.

I've tried everything from high 30s down to 15. Depending on the surface and ambient temps, i found the sweet spot for me to be in the low 20s.
The car will feel weird with that low of a tire pressure but actually stick better. Once you get used to the odd feeling.

Try starting out in the low 30s and go down during the day and see what that does for your times ...
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Thanks, the car was set up for PCA Club Racing, I plan on running the rubber which is currently on the car and then make a decision which direction to go with tires. Either stick with goodyear 250's or go with dot autox tires
URY914
Start at 28 and you'll be going down from there.
SirAndy
QUOTE(URY914 @ Jun 12 2013, 12:47 PM) *
Start at 28 and you'll be going down from there.

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And one more thing, when you change pressures, change them significantly. Otherwise you're wasting your (limited) time.

Don't go from 30 to 29 during runs, you won't be able to tell the difference.

If you go from 30 to 25, you *will* feel the difference.
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ChrisFoley
Hot pressure should be around 25-26psi.
That means you'll start around 21-22 cold for AX, and 19-20 for track time.
Randal
QUOTE(SirAndy @ Jun 12 2013, 12:25 PM) *

The 430 are too hard for AX, IMHO. I'm running the 250 which are the softest GY you can get and even those never get up to temp.
In my experience, they work better with much lower pressures than one would usually run.

I've tried everything from high 30s down to 15. Depending on the surface and ambient temps, i found the sweet spot for me to be in the low 20s.
The car will feel weird with that low of a tire pressure but actually stick better. Once you get used to the odd feeling.

Try starting out in the low 30s and go down during the day and see what that does for your times ...
popcorn[1].gif




Andy is right, although having run Goodyear for a long time, I'd even start lower.

My sweet spot was running 250's 18/20 or even 17/19 (F/R) on a 1700# car. Get them hot and they will make your day! They definitely go through a metamorphosis when they get hot, i.e., from mechanical grip to sticky grip. biggrin.gif Like lap 3 at Medford after having run through 30 corners on the way to 65 corners in a 4+ minute run.

I would guess that Paul (URY914) with his super light light weight 914, probably runs in the 20's.
grantsfo
Yep take it from guys who have ax'd these tires, me included. 430 is an awful ax compound make sure you have a co driver! I'd go with 18F/20R hot and no more. You want some flex to generate heat. Believe me you will need it with those stones! Frankly I think there are some street tires with more available grip than 430 in AX. 250s are barely passable as AX tire. 430 is going to make your car push like a pig in AX until you can get some heat up front.

What alignment setings are you going with? Your going from Radial to Bias ply. You will want to pull most of negative camber out of your current setup. no more than say -.75 camber.

My vote for long term tires are either Hoosier A6 or Avon A15 compound. I also saw very fast AX 914 running M&H drag radials - I talked to M&H and they said yep people are going with higher pressures in their radial drag slicks and doing very well in AX events. Worth looking at that option too.
nolift914
Am I wasting my time with the 430's , I have a set of Nitto NT-01's 225/45r15's on 8x15 fuchs which I run on my p3 class 944. should I forgo the slicks and run the nitto's. I figured the camber settings would be off going from a cantilevered slick to DOT R-compound. I haven't gotten the car on the alignment rack yet, I am assuming the PO has a track bias ply slick setup on the car with very little camber.

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URY914
I started last weekend at 24 and went down to 20 by my forth run.
ThePaintedMan
Yeah... how did that go Paul?? T.C. let me know a little too late, otherwise I would have come to watch! Let a guy know next time will ya? poke.gif
Randal
QUOTE(nolift914 @ Jun 12 2013, 01:59 PM) *

Am I wasting my time with the 430's , I have a set of Nitto NT-01's 225/45r15's on 8x15 fuchs which I run on my p3 class 944. should I forgo the slicks and run the nitto's. I figured the camber settings would be off going from a cantilevered slick to DOT R-compound. I haven't gotten the car on the alignment rack yet, I am assuming the PO has a track bias ply slick setup on the car with very little camber.

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AHHHH. Your the guy who bought John's car. OK.

Yea throw the 430 compound tires away or keep them for the track. They work fine on the track but don't work in AX. Running 430 compound for AX would be like running street tires, i.e., they are really hard.

Also knowing that car I'd get a set of GY 250 compound take offs and run them for awhile, get used to the car then buy a new set. And for the second step: You might want to look at a staggered setup and Avons. Unfortunately the Avon's aren't cheap, but I used Goodyear takeoffs for years and wanted to go faster. Avon's are way better for AX than the Goodyears. It's a shame the old (240 or whatever) compound that Goodyear offered went away. They worked much better than the 250 compound.
9146racing
i start (pending on weather) @ 19 1/2 and end up around 24, works on the track, dont know how they heat up at autocross though. but they like 24!
ChrisFoley
Since the car is already set up and you have the tires, I say take them to the autocross for a first hand experience.
I set FTD once on Hoosier R45s on my third run of the day.
The tires were useless on the first run, felt better on the second run, and were coming into their own halfway thru the third.
A second driver would help warm up the tires.
Randal
QUOTE(Racer Chris @ Jun 13 2013, 08:37 AM) *

Since the car is already set up and you have the tires, I say take them to the autocross for a first hand experience.
I set FTD once on Hoosier R45s on my third run of the day.
The tires were useless on the first run, felt better on the second run, and were coming into their own halfway thru the third.
A second driver would help warm up the tires.



Do they allow 3 drivers? biggrin.gif

If you want to run the 430's, no question lower pressures will help to get them warm.

And if allowed run a skid pad, both ways, right before you take them out.
mskala
I have nothing relevant to add here, but consider bringing that thing to pca zone1 autocross in august piratenanner.gif
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nolift914
QUOTE(mskala @ Jun 13 2013, 09:46 AM) *

I have nothing relevant to add here, but consider bringing that thing to pca zone1 autocross in august piratenanner.gif
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For the last few years I have run my P3 944 at the Zone 1 Auto X, which I won the P3 class at the Savannah Parade.

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This year may be different piratenanner.gif

In the 90's this was my Zone 1 ride

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nolift914
QUOTE(Racer Chris @ Jun 13 2013, 07:37 AM) *

Since the car is already set up and you have the tires, I say take them to the autocross for a first hand experience.
I set FTD once on Hoosier R45s on my third run of the day.
The tires were useless on the first run, felt better on the second run, and were coming into their own halfway thru the third.
A second driver would help warm up the tires.


Chris thank you for your advice, I think I am going to run the car as I bought it so I can set a baseline.

To all thank you for all the input and advice
nolift914
Thank You all for the help,

I ran the 430 slicks at my first AutoX with the 914 at the NYR SCCA event at Nassau Coliseum this past Sunday. I started the tires at 20psi which is what the PO had them set at. The amount of grip was a big step up from what I have been use to, running a stock 944 with Nitto NT-1's.

I found the turn in on the slicks a bit slower than the radials but the level of grip was impressive, I can only imagine what a GY 250 or Avon a15 is like.

I quickly realized how much more physical it is running a 914 is compared to a car with power steering, been spoiled these last 15 years.

I am looking forward to re-learning how to drive a 914 at speed. smilie_pokal.gif
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