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Old 06-12-2011, 01:35 PM   #1
lllarrolll
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Default Tire Pressure?

Just wondering what PSI everyone uses in their tires. I have aftermarket tires and wheels. 17x7, Dunlop Direzza Star Spec. Max PSI is 51. Right now I have 36 in all four. Is that good? Can someone explain the benefits of higher or lower tire pressure? I use the car as a daily driver, a little spirited driving sometimes, and I want to start doing autox soon. Thanks!
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Old 06-12-2011, 01:52 PM   #2
razrielle
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depends, I put 40 if Im doing highway driving not in bad weather (if I know), 35ish city
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Old 06-12-2011, 02:00 PM   #3
lllarrolll
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I do about 5 minutes city and 5 minutes highway going to work, same back. Other than that I don't drive often.
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Old 06-12-2011, 02:00 PM   #4
Euclid
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Whatever is printed on my door jamb.
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Old 06-12-2011, 02:01 PM   #5
lllarrolll
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I looked there and couldnt find it!
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Old 06-13-2011, 08:35 AM   #6
buki_JB
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Quote:
Originally Posted by lllarrolll View Post
I looked there and couldnt find it!
It's on there, keep looking.

Higher pressure:
- Reduced grip
- Uneven treadwear (centerline wears faster than shoulders)
- Better rolling resistance
- Better hydroplaning performance (Due to reduced footprint area, ymmv tho)

Lower pressure:
- Uneven treadwear (shoulders wear faster than centerline)
- Worse hydroplaning performance (Increased footprint area, again, ymmv)
- Possibly slightly increased grip (there is a dropoff point here)
- Worse rolling resistance

That's all I can think of off hand...in short, run what is recommended for your vehicle. There are few reasons why you would want to increase or decrease it for daily driving.

Last edited by buki_JB; 06-13-2011 at 08:43 AM.
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Old 06-13-2011, 08:53 AM   #7
jonklein611
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Tire Rack's Technical Section has a TON of info on tire tech.



Air Pressure - Tire Inflation

Air Pressure - Correct, Underinflated and Overinflated
http://www.tirerack.com/tires/tirete...e.jsp?techid=1


Air Pressure vs. Dry Performance
http://www.tirerack.com/tires/tirete...e.jsp?techid=2


Air Pressure vs. Wet Performance
http://www.tirerack.com/tires/tirete...e.jsp?techid=3


Air Pressure, Temperature Fluctuations
http://www.tirerack.com/tires/tirete....jsp?techid=73


Air Pressure, Time Fluctuations
http://www.tirerack.com/tires/tirete....jsp?techid=74


Air Pressure/Load Adjustment for High Speed Driving
http://www.tirerack.com/tires/tirete....jsp?techid=72


Air Pressure: When and How to Set
http://www.tirerack.com/tires/tirete...jsp?techid=147


Checking Tire Inflation Pressure
http://www.tirerack.com/tires/tirete...e.jsp?techid=8


Clearing the Air About Nitrogen Tire Inflation
http://www.tirerack.com/tires/tirete...jsp?techid=191


The Influence of Altitude Changes on Tire Pressure
http://www.tirerack.com/tires/tirete...jsp?techid=167


Tire Valve Types, Components and Uses
http://www.tirerack.com/tires/tirete...jsp?techid=208


We're Checking Who's Checking Spare Tire Pressures
http://www.tirerack.com/tires/tirete...jsp?techid=185


We're Checking Who's Checking Tire Pressures
http://www.tirerack.com/tires/tirete...jsp?techid=165
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Old 06-13-2011, 11:54 AM   #8
06blksti89
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i always have all 4 at 36.
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Old 06-13-2011, 10:34 PM   #9
TheTesseract
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For me 35 front 33 back. my door sticker says 33 front and 32 back
For autocross I been running about 40 front and 33-35 back. I am still feeling it out.

36 in all four is good, as long as you're some where near what the door says your should be fine. Look for a sticker on the driver side, not on the door but on the sill. That is where it in on the '10 wrx wagons.

Also go for read the tire rack info, more than you would ever want to know and will answer every technical question you could ever want to ask.
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Old 06-14-2011, 10:25 PM   #10
575rider
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Quote:
Originally Posted by lllarrolll View Post
I do about 5 minutes city and 5 minutes highway going to work, same back. Other than that I don't drive often.
You're not even driving far enough for your tires to heat up. For you, anything above 32 is going to be fine. I believe Subaru recommends 33fr and 32rr, may be slightly diff on your vehicle, but it's on the sticker in the driver side door jamb.
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Old 06-14-2011, 11:02 PM   #11
KLZCYA
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I run 40 all around. Haters gonna hate.
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Old 06-15-2011, 12:53 PM   #12
nwegel11
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36f 34r
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Old 06-15-2011, 01:27 PM   #13
EdHilario
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36F and 35R
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Old 06-15-2011, 03:03 PM   #14
bpang1
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40 Front and 34 Rear. This is the best so far for my auto-x needs and is fine on the street. Gives me neutral handling with the ability to coax oversteer with the brake pedal and understeer with the gas pedal.
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Old 06-15-2011, 03:32 PM   #15
cmiovino
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I used to roll with 50F/47R in my Kuhmo ASXs... the outsides would wear out hardcore. Then I made the front max negative camber and it's helped considerably. The sidewalls on these are very flexible. I now run that 43/40 now that they're even again. It works for me.
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Old 06-16-2011, 11:28 AM   #16
Vew
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When we did our autox runs, we'd put white shoe polish on the edge of the tread to the edge of the sidewall, overlapping a little. After our 1st run, you can see how much contact your tire made. If there was still polish on the tread, it was overinflated. If polish was missing from the sidewall, it was under inflated.
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