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Old 06-11-2013, 08:25 PM   #1
HAL1
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Default New 2013 delivered at 40 psi tire pressure

My car came new from the dealer at about 40 front and 40 rear. I know that's a bit high but I have been comfortable with it's driving characteristics.

Is this TOO high? I'm most concerned about handling and stiffness even at the expense of excessive wear. Summer in Phoenix is above 105 every day if that means anything
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Old 06-11-2013, 08:28 PM   #2
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just dial it down then
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Old 06-11-2013, 08:28 PM   #3
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Why don't you try lower it, and see if the handling changes to the point that you don't like it?
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Old 06-11-2013, 09:24 PM   #4
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Originally Posted by subaru3169 View Post
just dial it down then
I meant I like the current handling but was wondering if there are compelling reasons that this 40/40 might be too high.
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Old 06-11-2013, 09:59 PM   #5
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there is NOTHING AT ALL wrong with running 40 psi in tires unless you determin through experimentation that 40psi is too much

tires are aired up at the factory for shipping so they dont flat spot in transit and so the car is 'firmer' and doesnt bounce so much

bloody hell
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Old 06-12-2013, 05:32 PM   #6
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Quote:
Originally Posted by Uncle Scotty View Post


there is NOTHING AT ALL wrong with running 40 psi in tires unless you determin through experimentation that 40psi is too muchl
More tire wear in the center?

The door card says 33/32
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Old 06-12-2013, 05:41 PM   #7
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Quote:
Originally Posted by dmk0210 View Post
More tire wear in the center?
This is 100% specific to the tire being used.

Quote:
The door card says 33/32
Right, for stock sizing and tires that came with the car. Again, its subjective and all comes down to the exact setup one uses.
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Old 06-12-2013, 07:41 PM   #8
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Quote:
Originally Posted by dmk0210 View Post
More tire wear in the center?

The door card says 33/32
OOOhhhhh...you are one of those who don't know what you are talking about

OK....got it
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Old 06-13-2013, 01:43 PM   #9
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Quote:
Originally Posted by sc00by4life View Post
This is 100% specific to the tire being used.



Right, for stock sizing and tires that came with the car. Again, its subjective and all comes down to the exact setup one uses.
The OP said the car was new from the dealer. OEM tires.

I agree that for my aftermarket wheels and tires, that info may no longer be valid.
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Old 06-13-2013, 01:43 PM   #10
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Quote:
Originally Posted by Uncle Scotty View Post
OOOhhhhh...you are one of those who don't know what you are talking about

OK....got it
Nice.

What I said is what it says in the owners manual.

So what is wrong with the information the OEM provides?

I mean seriously, I'm asking.

Last edited by dmk0210; 06-13-2013 at 02:05 PM.
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Old 06-13-2013, 02:04 PM   #11
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The OEM "recommended" pressure on the plate by the door is the minimum pressure they think most of their customers will like the best in terms of ride, handling. As long as you do not exceed the tire manufacturers MAXIMUM pressure ( which is on the sidewall) you should be safe though your ride may be a little harder at very high pressures but its all different strokes for different folks.
Better 5 over than 5 under for any tire pressure! Unless you want to be like the Ford Explorer and Firestone tire affair.

One thing which has always puzzled me is that while they always say its the cold pressure which is important. What if you do wake up in the mountains of AZ say and the pressure is just below the tire manufacturers max and then the temp rises say 4o deg F (which should be a 4psi change) over the course of the day say . Should you adjust for that?
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Old 06-13-2013, 02:06 PM   #12
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I've been running mine around 36-42psi for a while. Higher pressure leads to a firmer ride and slightly better wear characteristics. I found that going higher than 46 or so makes it wear the center of the tread more but again it will depend on what tire you have.

Nothing wrong at all with 40psi.
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Old 06-13-2013, 02:08 PM   #13
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Quote:
Originally Posted by dmk0210 View Post
The OP said the car was new from the dealer. OEM tires.

I agree that for my aftermarket wheels and tires, that info may no longer be valid.
its also based on subaru's fuel economy/comfort targets.

there is no reason you can't play around with tire pressures. 40psi in that tire might not necessarily be "over filled" which would cause excessive center wear.
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Old 06-13-2013, 02:53 PM   #14
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Thanks for the intelligent answers guys.

I've always been worried about going higher than 38 or so, figuring it's going to heat and raise pressure as you drive.

Quote:
One thing which has always puzzled me is that while they always say its the cold pressure which is important. What if you do wake up in the mountains of AZ say and the pressure is just below the tire manufacturers max and then the temp rises say 4o deg F (which should be a 4psi change) over the course of the day say . Should you adjust for that?
My understanding is that the OEM pressures are at something like 60-70deg f. ("room temperature"). Since tires warm up as you drive, I'd think the 40deg outside air temp would be negligible.


Everything I've read says check it in the morning, but what if it's minus 10deg in the middle of the winter? I suppose you are supposed to add a few lbs if it is under room temp?
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Old 06-13-2013, 09:47 PM   #15
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Quote:
Originally Posted by cptplt View Post
The OEM "recommended" pressure on the plate by the door is the minimum pressure they think most of their customers will like the best in terms of ride, handling. As long as you do not exceed the tire manufacturers MAXIMUM pressure ( which is on the sidewall) you should be safe though your ride may be a little harder at very high pressures but its all different strokes for different folks.
Better 5 over than 5 under for any tire pressure! Unless you want to be like the Ford Explorer and Firestone tire affair.

One thing which has always puzzled me is that while they always say its the cold pressure which is important. What if you do wake up in the mountains of AZ say and the pressure is just below the tire manufacturers max and then the temp rises say 4o deg F (which should be a 4psi change) over the course of the day say . Should you adjust for that?

you shouldn't adjust tire pressures like that or for that...and there is no reason to be anywhere near max inflation, cold
That can be VERY bad as it can cause loss of control...for many reasons

depending on the tire, the MAX inflation should be 44-51psi.....if you start at 36psi...you wont get anywhere near that
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Old 06-17-2013, 02:26 PM   #16
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I enjoy my STI best with 38-40 PSI of air in them.
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