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Tire Pressure Discussion?

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Old Dec 1, 2008 | 06:49 PM
  #1  
chrisok5's Avatar
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From: San Jose, CA
Car Info: 2003 Impreza OBS
Tire Pressure Discussion?

Can someone post a link of a good tire pressure discussion?

I'm trying to get better mileage and wear out of my tires. I just had the Goodyear EagleResponse Edges mounted on my all stock 2003 Outback Impreza.

For the life of my car, I've ran the recommended tire pressure but the they always seem to wear faster on the inside fronts (25K average). The front passenger more than the others.

I rotate the tires religiously and my alignment is checked regularly.

Correct me if I'm wrong but the tire wear indicates running the PSI too low.

My mechanic highly recommends the tire pressure as advised by Subaru because any adjustments may cause negative affects on the differential and transfer case.

Could I run a higher pressure at the same front to back ratio and be safe?

BTW - I ran the OEM tires twice and the Pzero Nero's most recently. Same tread wear and life.

Thanks in advance.

Chris
Old Dec 14, 2008 | 01:51 PM
  #2  
subie OCD's Avatar
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Wear on the inside fronts is probably due to the toe specs on the alignment. Did you get a print out of the alignment specs? You want to have zero toe all around and a bit of negative camber up front (make sure the negative camber is even for the left and right).

Also, make sure the back tire pressure is 2-4psi lower than the front (for drivetrain safety).

On my Impreza WRX STi, I have -1.0 degree camber up front (left and right) and zero toe all around. Dont worry about castor or rear camber as they aren't really adjustable unless you buy aftermarket parts. My setup is semi aggressive for spirited driving and I have very even tire wear...I use Sumitomo HTR Z III tires with tire pressure 37F and 34R. For a daily driver like an outback I would recommend -0.6 camber up front and maybe try increasing the tire pressure and see what you like best. Tire pressure is more of a personal preference.....I think Subaru tire pressure specs are more for comfort so you could get away with increasing it safely.

Hope this helps.

Last edited by subie OCD; Dec 14, 2008 at 01:55 PM.
Old Dec 15, 2008 | 12:41 AM
  #3  
chrisok5's Avatar
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From: San Jose, CA
Car Info: 2003 Impreza OBS
great. Thanks for the break down.

Do tire shops do good enough alignment jobs or wohrisuld it be best go to a performance shop?

Also, how often do you have your car realigned.

Thanks again,

Chris
Old Dec 15, 2008 | 10:34 AM
  #4  
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Car Info: 04 wrx, 05 Elise, 14 Impreza, 17 brz coming soon
Originally Posted by chrisok5

Could I run a higher pressure at the same front to back ratio and be safe?

Chris
yes,

to maintain good mileage per gallon, just make sure tires are inflated to spec+. zero toe is very important for tire wear, as well as minimizing camber. for daily driving -.8 or -1 up front is a great place to start. make sure the alignment tech is adjusting camber before he or she adjusts toe, but im 99.9% sure they already know that.

re-check/adjust alignment anytime you adjust or move around the geometry of the suspension, but naturally over time alignment will move around just a bit by itself, so it wont hurt to check it at least every 6 months or so..
Old Dec 16, 2008 | 06:50 PM
  #5  
subie OCD's Avatar
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Originally Posted by chrisok5
great. Thanks for the break down.

Do tire shops do good enough alignment jobs or wohrisuld it be best go to a performance shop?

Also, how often do you have your car realigned.

Thanks again,

Chris
Im sure any reputable alignment shop could do it, just make sure to tell them the specs and they give you a printout. If they dont want to do that, take it elsewhere. Not sure where you're located but there are lots of community subforums you can search.

As for how often, that most likely depends on each person ...I just watch the tire wear and how straight the car drives. It would probably be good to check once or twice a year if you have harsh bumpy roads or do off-roading.

Last edited by subie OCD; Dec 16, 2008 at 06:53 PM.
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