AutoXing an A10 GT, what gear should I run?

[CXRs]

Hey guys, as is my tradition, taking my car to its first autoX.

This is my first time in the Stang, but not first session. I'm calling all you guys with A10s and 3.15s, what works for you?

Car is stock at this point, down to the 255 Pirellis. My preliminary thoughts are to go for track mode so I'm not too hampered by TC, and leave the shifter in S so I can hold gears. I know that short tracks can really trip up track modes, so I'm plenty open to suggestions. My questions are as follows:

Should I use track mode, or sport mode? Or just go for normal so it feeds in the throttle a little smoother?

Should I go for D or S?

TC partially off, or hold it and go for broke with no stability control?

Car is a 22 with 3.15s, no suspension, stock 255s on the heavy blackout package wheels. Will be running ~39psi.

Suspension and shoes coming in the winter, this one is all about the driver mod.

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[EFI]

S and use the paddles to keep in a certain gear. If you let it be in the auto mode (whether normal or sport) it's going to keep up and downshifting at the wrong times. The right gear is going to be determined by many factors only which you can determine at the time. Generally you want to be in the lowest gear that gives you traction.

 

[Dana Pants]

At all times, the less thinking sand interfering with your driving the better. All stability control off. Manual gear selection only. You will figure out pretty fast what gear is appropriate for you.

 

[Cory S]

39psi cold is too much. 32-33 COLD as a starting point. You will see about a 1psi increase for every 10°F increase internal air temperature in the tire.

 

[CXRs]

39psi cold is too much. 32-33 COLD as a starting point. You will see about a 1psi increase for every 10°F increase internal air temperature in the tire.

I don't wanna roll over the tires and burn off the edges too bad. I typically run about 34-35psi cold on the street and have remarkably good wear characteristics as-is, so I'm thinking a couple extra pounds ought to do. When I'm out looking for trouble I usually bring it down to ~26-28 but that's about it so far.

I'm still on 255s so will likely need to reduce all of those numbers by a few lbs when I step up to 285+

 

[EFI]

I typically run about 34-35psi cold on the street and have remarkably good wear characteristics as-is, so I'm thinking a couple extra pounds ought to do.

A couple extra pounds will do yes, but it's usually down not up. If you're running 35 on the street, you take that down 3 to 32 for the track (not up 3 to 38). Track driving heats up the tires much more than street driving, so you want to compensate for that by running less pressure to start with.

 

[CXRs]

A couple extra pounds will do yes, but it's usually down not up. If you're running 35 on the street, you take that down 3 to 32 for the track (not up 3 to 38). Track driving heats up the tires much more than street driving, so you want to compensate for that by running less pressure to start with.

I'm talking about autocross, not drag strip. Airing the tires down gets you more sidewall flex, and puts you on the outer edges of the tire. Since you're taking corners harder than you would on an open track, you load the tires up far more than you ever would on the street, and need to maintain your contact patch shape with the leading tires.

I didn't realize it, but tirerack has a decent article on it: https://www.tirerack.com/upgrade-garage/what-tire-air-pressure-do-i-use-for-track-and-autocross

 

[Dana Pants]

I have run as high as 39 psi front in FS class at autocross.

 

[EFI]

I'm talking about autocross, not drag strip. Airing the tires down gets you more sidewall flex, and puts you on the outer edges of the tire. Since you're taking corners harder than you would on an open track, you load the tires up far more than you ever would on the street, and need to maintain your contact patch shape with the leading tires.

I'm talking about roadcourse driving, not dragstrip. You're gonna have a helluva time with traction on 40+psi street tires on a slow autox course, but hey at least it will be fun going sideways around every cone.

The point we are trying to make is that driving hard like this puts more air into the tire, so whatever pressure you have on the street you need to lower it on a road course or autox in order to compensate for that. Starting with 39psi cold is way way way too much, heck 39psi hot is too much for most tires. You should be aiming for ~36 hot, meaning you should be starting in the low 30s cold.

 

[CXRs]

I'm talking about roadcourse driving, not dragstrip. You're gonna have a helluva time with traction on 40+psi street tires on a slow autox course, but hey at least it will be fun going sideways around every cone.

The point we are trying to make is that driving hard like this puts more air into the tire, so whatever pressure you have on the street you need to lower it on a road course or autox in order to compensate for that. Starting with 39psi cold is way way way too much, heck 39psi hot is too much for most tires. You should be aiming for ~36 hot, meaning you should be starting in the low 30s cold.

Thank you for the idea, and I'll try it in a couple days when I take it out again. I skipped over 36psi when I did my test runs on the roads I drive, so I'll try it and see if it helps.

 

[Trophy Hunter]

I thought that I would chime in due to the prior posts.
In my opinion, you are correct and in reading your post, it sounds like you've autocrossed before - with a street tire and specifically to autocross, we are making quick, abrupt changes, much different then other type of car racing. Like you alluded to, sidewall flex is the issue and with a true street tire there is usually a little more ....... even with a P-0 (if that's what you have). The big question is - is cold truly cold, of are you driving up on the same tire and do you have an "autocross alignment" or is it stock/street ?
I have not used the P-0 myself in autocross (so keep that in mind) but they do have a treadwear of 220 (ie pretty sticky for a street tire). If you drive up to the event, I would try 34 psi rear and 36 front (for an autocross alignment) and markt the tires (chalk/shoe polish). Run at about 85% effort (on your part) on your first run to get a feel of the tire (and to not over cook them with blowing a corner and plowing) and go from there. Again, I have not run the P-0 but I think at the end of the day you'll probably find comfort at those temps for heated tires but its better to be safe to start.

Best of luck and have fun !
Side note - for a street alignment, I would suggest adding a few psi to the front to start.

 

[CXRs]

I thought that I would chime in due to the prior posts.
In my opinion, you are correct and in reading your post, it sounds like you've autocrossed before - with a street tire and specifically to autocross, we are making quick, abrupt changes, much different then other type of car racing. Like you alluded to, sidewall flex is the issue and with a true street tire there is usually a little more ....... even with a P-0 (if that's what you have). The big question is - is cold truly cold, of are you driving up on the same tire and do you have an "autocross alignment" or is it stock/street ?
I have not used the P-0 myself in autocross (so keep that in mind) but they do have a treadwear of 220 (ie pretty sticky for a street tire). If you drive up to the event, I would try 34 psi rear and 36 front (for an autocross alignment) and markt the tires (chalk/shoe polish). Run at about 85% effort (on your part) on your first run to get a feel of the tire (and to not over cook them with blowing a corner and plowing) and go from there. Again, I have not run the P-0 but I think at the end of the day you'll probably find comfort at those temps for heated tires but its better to be safe to start.

Best of luck and have fun !
Side note - for a street alignment, I would suggest adding a few psi to the front to start.

It's been a blur of work the past few weeks, but I'm finally getting out tomorrow.

And yes, I've run a number of events the past few years. It's something I try to do when I have time to keep my skills sharp and to learn a new car.

Right now I'm stock as can be on alignment specs. I'm gonna get it dialed before I put it away for winter, and make some changes to the suspension. I'm finding the stock 255s to be not nearly as grippy as I'd like, but they're getting changed when I find a wheel/tire combo I like. It's tricky finding something light, wide, and not 1k/ea

 

[RagmopInKona]

I'm talking about autocross, not drag strip. Airing the tires down gets you more sidewall flex, and puts you on the outer edges of the tire. Since you're taking corners harder than you would on an open track, you load the tires up far more than you ever would on the street, and need to maintain your contact patch shape with the leading tires.

I didn't realize it, but tirerack has a decent article on it: https://www.tirerack.com/upgrade-garage/what-tire-air-pressure-do-i-use-for-track-and-autocross

39psl cold is to high. Unless you really want 42 psi at mid run. I would not want that psi . Surd you won't burn off the sides you'll burn down the center of the tread and have less contact patch. BRING A TEMP GUN AND RECORD readings inner , center, outer of the tread. Use that as your guide.

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