Re: What Tire Pressure do you run?
[Re: challenger70]
#2643878
04/10/19 10:02 PM
04/10/19 10:02 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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Curious to see the responses but I suspect the right answer for each car will vary quite drastically between setups, intended use, driving styles, tire compounds, and tire load ratings.
For me, I run 34 front/ 32 rear, just a spirited street car, no competition.
Last edited by GoodysGotaCuda; 04/10/19 10:03 PM.
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Re: What Tire Pressure do you run?
[Re: MuuMuu101]
#2643896
04/10/19 10:45 PM
04/10/19 10:45 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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It really depends. If you have some grocery getter with tall side walls upping the tire pressure can help some. But it'll still be a pig and always will.
With short sidewall tires, I tend to use the same method as the drag racers but on all four corners. Drive thru a shallow puddle and note the tracks left. narrow, center stripe lower pressure a bit. no center stripe up the pressure. track width pretty much matches the tread that's where you start. If the rear feels wiggly you're too low, if the front feels mushy your too low.
Get a different set of tire, do it all over again.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: What Tire Pressure do you run?
[Re: challenger70]
#2643911
04/11/19 12:17 AM
04/11/19 12:17 AM
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Joined: Aug 2004
Posts: 3,310 Walnut Creek, CA
blown340
master
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master
Joined: Aug 2004
Posts: 3,310
Walnut Creek, CA
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Get some shoe polish and stripe it from the sidewall down onto the tread. Adjust pressures until when you run hard you wear it evenly off the tread but not off the sidewall. I've always done it this way on my autoX and track cars and its worked really well. For a generic recommendation I usually end up at about 42psi front and 38psi rear for lower profile tires on heavyish front engine rear wheel drive cars.
Obviously for significant street miles you might want to go with a lower pressure and then just increase it for the track/autoX. This is what I do and I generally run 32 to 36 on the street depending on the car and tire.
-Jon
70 challenger convertible. 340/5 speed. blown, intercooled, efi, blah blah blah
71 valiant scamp 318/A833OD/AC/PS
00 dakota RC 4.7L 5 spd autoX'r. SRT10/T56 swap in process
73 W200 Power wagon, PTO winch, 4 spd
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Re: What Tire Pressure do you run?
[Re: blown340]
#2643935
04/11/19 08:04 AM
04/11/19 08:04 AM
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Joined: Jan 2003
Posts: 7,545 Albany, NY
67SATisfaction
The member whose name is actually Art
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The member whose name is actually Art
Joined: Jan 2003
Posts: 7,545
Albany, NY
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Results vary, but I start with 34psi cold, with a target of 41psi hot..
..which I verify and tweak each track day by measuring and comparing the temperature of the tire surface at three places across the width the tire: Inside, Center and Outside. I make a little chart each time for each tire. You can use an inexpensive IR 'laser' temperature reader, or an expensive needle gauge. The goal is an even temperature across the width of each tire. Hotter in center is too high pressure. Cooler in center is too low pressure.
For the drive home I go with car Mfr's recommendations.
Last edited by 67SATisfaction; 04/11/19 08:08 AM.
65 Satellite hardtop 361/4bbl console 727 2.76 67 Satellite convert 383/2bbl column 727 3.23 67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd 67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd 71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd 82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle 75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF 77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF 07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
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Re: What Tire Pressure do you run?
[Re: DynoDave]
#2644393
04/12/19 11:56 AM
04/12/19 11:56 AM
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Joined: Jan 2010
Posts: 1,442 NW Chicago suburban area
Mopar Mitch
pro stock
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pro stock
Joined: Jan 2010
Posts: 1,442
NW Chicago suburban area
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So many variables... and the final PSI can change with different vehicles, tires/wheels (different tires of same size can run different psi), daytime temperatures, weather conditions ... the main decision is per event... street, highway, pylon autocross, hi-speed lapping (HSAX/HPDE). For performance driving (AX.HSAX, etc)... always increase a little vs daily driving. Where the heavier weight is (front engine)... run 2-4-6 psi higher than rear. Example street/hwy... front 34, rear 32..... AX/HSAX front 40, rear 36.. (some cars/tires etc... f 45, r 40, etc). You can also dial in understeer/oversteer/nuetrality.. experience and multiple events will tell you that.l Look at TIRE RACK web site as they offer some recommendations. For competition events, the chalk or shoe polish is a good practice, as well as temp measurements. NOTE: www.mcscc.org MIDWESTERN COUNCIL OF SPORTS CAR CLUBS will have 5 season HSAX events this year 2019... Blackhawk Farms Raceway (HSAX School April April 27, HSAX race #1 May 27, HSAX race #2 July 5, HSAX race #3 July 6 (that's my club's race weekend!.. www.nsscc.org hope to see you there!). Joliet Autobahn HSAX race #4 July 20. BHF HSAX race #5 August 24. All these events are on www.motorsportreg.com for pre-registration (cost savings to pre-reg!). Also, all these events are HPDE (lapping sessions) morning and competition HSAX afternoon.
Last edited by Mopar Mitch; 04/12/19 12:02 PM.
Mopar Mitch
"Road racers and autocrossers go in deeper and come out harder!"... and rain never stops us from having fun with our cars... in fact, it makes us better drivers!
Check out MOPAR ACTION MAGAZINE, August 2006 issue for feature article and specs on my autocross T/A!
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Re: What Tire Pressure do you run?
[Re: Mopar Mitch]
#2645965
04/17/19 09:54 AM
04/17/19 09:54 AM
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Joined: Mar 2003
Posts: 3,358 Berwyn, IL
challenger70
OP
master
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OP
master
Joined: Mar 2003
Posts: 3,358
Berwyn, IL
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Definitely going to try to make what I can So many variables... and the final PSI can change with different vehicles, tires/wheels (different tires of same size can run different psi), daytime temperatures, weather conditions ... the main decision is per event... street, highway, pylon autocross, hi-speed lapping (HSAX/HPDE). For performance driving (AX.HSAX, etc)... always increase a little vs daily driving. Where the heavier weight is (front engine)... run 2-4-6 psi higher than rear. Example street/hwy... front 34, rear 32..... AX/HSAX front 40, rear 36.. (some cars/tires etc... f 45, r 40, etc). You can also dial in understeer/oversteer/nuetrality.. experience and multiple events will tell you that.l Look at TIRE RACK web site as they offer some recommendations. For competition events, the chalk or shoe polish is a good practice, as well as temp measurements. NOTE: www.mcscc.org MIDWESTERN COUNCIL OF SPORTS CAR CLUBS will have 5 season HSAX events this year 2019... Blackhawk Farms Raceway (HSAX School April April 27, HSAX race #1 May 27, HSAX race #2 July 5, HSAX race #3 July 6 (that's my club's race weekend!.. www.nsscc.org hope to see you there!). Joliet Autobahn HSAX race #4 July 20. BHF HSAX race #5 August 24. All these events are on www.motorsportreg.com for pre-registration (cost savings to pre-reg!). Also, all these events are HPDE (lapping sessions) morning and competition HSAX afternoon.
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Re: What Tire Pressure do you run?
[Re: challenger70]
#2716060
11/15/19 11:12 AM
11/15/19 11:12 AM
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Joined: Jan 2003
Posts: 7,545 Albany, NY
67SATisfaction
The member whose name is actually Art
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The member whose name is actually Art
Joined: Jan 2003
Posts: 7,545
Albany, NY
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Definitely going to try to make what I can So many variables... and the final PSI can change with different vehicles, tires/wheels (different tires of same size can run different psi), daytime temperatures, weather conditions ... the main decision is per event... street, highway, pylon autocross, hi-speed lapping (HSAX/HPDE). For performance driving (AX.HSAX, etc)... always increase a little vs daily driving. Where the heavier weight is (front engine)... run 2-4-6 psi higher than rear. Example street/hwy... front 34, rear 32..... AX/HSAX front 40, rear 36.. (some cars/tires etc... f 45, r 40, etc). You can also dial in understeer/oversteer/nuetrality.. experience and multiple events will tell you that.l
Look at TIRE RACK web site as they offer some recommendations.
For competition events, the chalk or shoe polish is a good practice, as well as temp measurements.
What Mitch and I are saying is, if you are in competition, you can't be satisfied with a "Oh, it's AX day and I'll run 4psi more than Mfr's recommendation... or "it's Track Day so I'll run 6psi more". That's just pure guessing. For competition - You want as even temperatures as possible because this implies your tires are contacting the pavement with equal traction. Uneven temperatures means the hotter areas of your tires are working harder than the cooler, and you're not getting full grip from the cooler parts of your tires. My temps range from 102F to 125F measured in the 'valley' of each tire's tread (which is a good location to measure because the 'valley' holds a temperature better than the contact surface which is affected by the pavement your car drove over after coming off the track). Either way, map your temp measurements from the same spots consistently each time you come off the track. I'm usually able to get within 5F, and on a good day within a 2F temperature spread, and I know from years of tracking my ideal temps are always near 41psi HOT right off the track, plus or minus 2psi. So, try a baseline pressure, get out on the track, and AS SOON AS PRACTICAL when you come off the track, make a chart of the tire temperatures across the face of each tire and take your tires pressures. Gather the data first and read it afterwards. You want a "map" of your tires' temperatures and pressures so you can read what the data tells you to do about it. What do you read? Something like 105-118-109 = High in the middle = Needs less pressure. Something like 120-111-122 = Low in the middle = Needs more pressure. Try 2-3psi increments. After you're confident mapping and adjusting tire temperatures, you can look at side to side temperatures to read what your alignment needs to be: Something like 105-109-114 = Clearly hot to one side = Adjust camber to put more weight on the cooler temperature. With a car aligned perfectly "symmetrically" driving on a left turning track, you'll often find the right side temperatures to be hot on the tires. So reduce camber on the driver's side tires and increase camber on the passenger side. What you want out of it will dictate how much time and effort you put into tire pressures. If you are just starting out, I'm guessing you could gain 0.2 - 0.5 seconds per 60 seconds of lap time. Tweaking alignment will bring gains too, but means scheduling with a shop or bringing dedicated equipment, which is another level. Cheers, - Art
Last edited by 67SATisfaction; 11/15/19 11:16 AM.
65 Satellite hardtop 361/4bbl console 727 2.76 67 Satellite convert 383/2bbl column 727 3.23 67 Lancia Fulvia Sport 1.3 Zagato. Alloy body, 1.3L V4 DOHC 4-spd 67 Lancia Fulvia Rallye 1.3. Alloy panel, 1.3L V4 DOHC 4-spd 71 Alfa Romeo GT Junior 1300 Zagato, 1.3L 4cyl DOHC hemi 5-spd 82 Alfa Romeo GTV6 2.5L SOHC hemi V6 5-spd transaxle 75 Maserati Bora US spec 4.9L DOHC hemi V8 5-spd ZF 77 Maserati Khamsin Euro spec 4.9L DOHC hemi V8 5-spd ZF 07 Aston Martin DB9 6.0L DOHC V12 6spd transaxle
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Re: What Tire Pressure do you run?
[Re: TC@HP2]
#2717409
11/19/19 04:49 AM
11/19/19 04:49 AM
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Joined: Aug 2005
Posts: 6,017 Salem
Grizzly
Moparts Proctologist
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Moparts Proctologist
Joined: Aug 2005
Posts: 6,017
Salem
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As low as I can get away with on the backs and +4 psig on the front. On BF's it's 32 and 36 for my E-bodies.
The paint/drive through a puddle method are good for starting points at 2 mph, but a tire changes shape when you are doing 50 mph.
Mo' Farts
Moderated by "tbagger".
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