HPDE Street Tire Pressures

[Budwise]

I've seen a pretty big range of recommendations, some saying 28-29 psi cold and some all the way up to 38 psi cold or so. In the past I've usually started around 32 and tried to keep it below 40 hot. I know the tire compound has some to do with this and I'm running a stickier tire now than I have in the past (RE11's vs MPSS's and S04's).

I'd like to hear from others on what they've tried and what has worked best. Did you actually take temp measurements across the tread or did you just "feel" it as you went?

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[Anthony@HTM]

Im running Hankook RS3s and start them off at 27F/28R

At full temp they get up to 35 psi all around and they are good to go.

Every tire has a sweet spot as far psi, in my opinion 40psi is too high at full temp. But for RE11s that might work well.

 

[Trackaholic]

Saw that the GT350 recommends 28 psi cold for track use. Not sure what the standard street recommendation is.

I definitely would not start at more than the street setting unless you want to stop after a couple laps to let air out.

On my 350Z I'll start at 35 (which is the street setting), and let air out after the first session to try any maintain a hot pressure of 39-40. Usually this means letting out roughly 7-8 PSI over the course of a couple sessions, which could correlate to Ford's recommendation of 28 PSI cold (assuming 35 PSI is the street recommendation).

Anything much over 40 PSI on track and I can feel the tires losing grip.

I also found that when I put my r-comps on for some street use, and forgot to pump them back up, they were @ maybe 22 PSI cold. That was WAAAYYY too low. The car felt like crap. Put them up to 35 for street use and things settled back down nicely.

-T

 

[Norm Peterson]

I try to keep "not quite hot" pressures to no more than about 37 (front) and 34 (rear). "Not quite hot" meaning after driving around paddock or on the access road a bit to cool the brakes before letting the car sit still for any appreciable length of time. An IRS car might want a slightly different amount of pressure stagger, but I doubt it'd be a whole lot different.


Norm

 

[Budwise]

So Anthony and Norm, one of you uses more pressure in the rear and the other in the front. Can you explain?

 

[Norm Peterson]

I use a little more in the front for responsiveness, and a little less in the rear for slightly larger slip angles back there (reduced understeer) and for a little more mechanical grip (cushion against oversteer if I add just a little too much throttle on cornere exit). I do have to be able to drive it home, so it's probably a little on the conservative side.

When I autocrossed a FWD car, ISTR that the pressure stagger eventually ended up being something like 37f/47r. Slightly undersize tires and a willingness to throw rear grip away for better rotation.


Norm

 

[Anthony@HTM]

So Anthony and Norm, one of you uses more pressure in the rear and the other in the front. Can you explain?

I found that the front tires on this car heat up more than the rears. So I found starting at 27/28 got me to 35 all around after a few laps.

 

[Brent Dalton]

Agree with Anthony. For the new mustang, it understeers. One small measure to help counter this is to have slightly less tire pressure in the front than the rear. Also of note, my TPMS reads 2psi higher than my actual gauge.

 

[apex15stangPP]

My goal is to never let my tires get above 35 PSI hot. The tires most people are running have a stiff sidewall belt package. Not to mention modern day "HOT" tires are basically race tires from 10 years ago. I'm currently running the RE-71R and I try to keep them around 140-155 across the tire and hot 35 psi. Cold isn't always has important because there are so many different set ups and driver styles.

 

[Anthony@HTM]

Agree with Anthony. For the new mustang, it understeers. One small measure to help counter this is to have slightly less tire pressure in the front than the rear. Also of note, my TPMS reads 2psi higher than my actual gauge.

That's strange, mine was dead accurate. We're these on the stock wheels?

I know that it did take sometime for it to show an adjustment for when I would lower the pressure at the track.

 

[Brent Dalton]

Yep, stock wheels. I used 2 different calibrated pressure gauges to confirm. Just good to know as a baseline. I'm sure there is a variance! You are absolutely right on it taking a about 15-30 seconds to show the pressure change on the dash gauge. I was trying to adjust the pressure with my dad watching the dash the first time I did it.

 

[Anthony@HTM]

Yep, stock wheels. I used 2 different calibrated pressure gauges to confirm. Just good to know as a baseline. I'm sure there is a variance! You are absolutely right on it taking a about 15-30 seconds to show the pressure change on the dash gauge. I was trying to adjust the pressure with my dad watching the dash the first time I did it.

Absolutely haha

My current set of wheels don't have them due to ford being out of stock for quite sometime now. Having it on the dash is a luxury, especially when you see everyone else running out of their cars after a session to check temps.

 

[Budwise]

Odd, my on-dash is spot on to my tire gauges.

 

[Impulsed7]

For anyone interested, stock PP pirelli's like ~37 psi indicated on the dash. Anything over starts to get greasy. On my calibrated tire pressure gauge (get it done at work), thats 36psi. NT-01's like 36psi exactly, and I will be going back to those once I get some wheel options in the garage.

 

[Grim12]

Was the FWD car the Maxima? Feel like I remember you from Maxima.org

I use a little more in the front for responsiveness, and a little less in the rear for slightly larger slip angles back there (reduced understeer) and for a little more mechanical grip (cushion against oversteer if I add just a little too much throttle on cornere exit). I do have to be able to drive it home, so it's probably a little on the conservative side.

When I autocrossed a FWD car, ISTR that the pressure stagger eventually ended up being something like 37f/47r. Slightly undersize tires and a willingness to throw rear grip away for better rotation.


Norm

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