45 psi in tires on Forester from factory?

[Frank Logullo]

My Forester is 3 months old and going in for free first oil change Wed.
In checking wife's tires today I checked mine and found the G900 Yokohoma
Geolanders to all be at 45 psi.
Thought gauge was defective and checked with 2 others and got same reading -
wife's tires were 32 lb as expected on her Nissan. Dealer says maybe all
three of my guages defective! No harm anyway since only result would be
higher mileage.
I'm not letting air out until I see him Wed. and have a little tete-a-tete

Frank

 

[Edward Hayes]

Typically tires when first mounted and shipped are pressurized to 45-50
psig. It was the dealer prepping the vehicle who is expected to set tires to
the correct pressure. You do check then overnight cold? as expect a one
pound increase for every ten degree in tire temperature. If you check after
a high speed run they can be up 10 psi easy. Eddie

 

[someone]

My Forester is 3 months old and going in for free first oil change Wed.
In checking wife's tires today I checked mine and found the G900 Yokohoma
Geolanders to all be at 45 psi.
Thought gauge was defective and checked with 2 others and got same reading -
wife's tires were 32 lb as expected on her Nissan. Dealer says maybe all
three of my guages defective! No harm anyway since only result would be
higher mileage.
I'm not letting air out until I see him Wed. and have a little tete-a-tete

Frank

I used to work at a Subaru dealership a couple years ago. It was very
common for the cars coming from the factory to have 45+ PSI. Part of the
"pre-delivery inspection" is checking/setting tire pressure. Don't know if
they still do or not, but when I was working in the dealership, the tires
even have BRIGHT green stickers on them stating something to the effect of
"Dealer set tire pressure" Sounds like whoever did the PDI on your vehicle
didn't do a very good job of it.

 

[Frank Logullo]

I used to work at a Subaru dealership a couple years ago. It was very
common for the cars coming from the factory to have 45+ PSI. Part of the
"pre-delivery inspection" is checking/setting tire pressure. Don't know if
they still do or not, but when I was working in the dealership, the tires
even have BRIGHT green stickers on them stating something to the effect of
"Dealer set tire pressure" Sounds like whoever did the PDI on your vehicle
didn't do a very good job of it.

Thanks for the comments. Don't know who I spoke to at the dealership but it
was not the service manager.
I'll set them straight tomorrow and have them reset pressures. Car has been
fine. It replaced '98 Forester that was totaled in an accident, but ride
not any smoother than '98. Maybe this will improve it.
Frank

 

[Richard Chang]

My Forester is 3 months old and going in for free first oil change Wed.
In checking wife's tires today I checked mine and found the G900 Yokohoma
Geolanders to all be at 45 psi.

Checked my '03 Forester after the first week at home and all four
tires were at 38psi, which is about 10psi higher than they should be.
(Yes, I checked the tires cold.) I don't think changes in ambient
temperature could account for this much difference in tire pressuer. I
suppose they could have filled it to 29psi when it's way below freezing.

-R.

 

[Ken Gilbert]

Thanks for the comments. Don't know who I spoke to at the dealership but it

was not the service manager.
I'll set them straight tomorrow and have them reset pressures. Car has been
fine. It replaced '98 Forester that was totaled in an accident, but ride
not any smoother than '98. Maybe this will improve it.
Frank

oh yeah, it will be smoother, no doubt, but expect to wallow around a
bit more too as you get reintroduced to sidewall flex!

i run 42 psi (cold) in all 4 corners of my wrx. treadwear is BETTER
than at stock suggested numbers, which are ridiculously low imho.

jm2c
ken

 

[Edward Hayes]

I presume you used P1XT1=P2XT2 where T = the absolute temperature??? Please
recheck calculation. Eddie

 

[David or Jo Anne Ryeburn]

I presume you used P1XT1=P2XT2 where T = the absolute temperature??? Please
recheck calculation. Eddie

P1/T1 = P2/T2 is more like it. Your formula would have the pressure
*decreasing* as the temperature increases.

If you assume a pressure of 29.3 lb/in^2 at a temperature of +20 C (+68
F), his calculation of 1 lb/in^2 increase for every 10 degrees C increase
is right on. And it agrees very nicely with my experience in checking tire
pressures at various temperatures (front tire pressure for my 1997 Legacy
Outback is 29 lb/in^2).

David

 

[Frank Logullo]

I presume you used P1XT1=P2XT2 where T = the absolute temperature??? Please
recheck calculation. Eddie

No, I start with gas law which is PV=nRT. I never remeber the
differences between Boyles and Charles law (which is which). T of
course is in degrees Kelvin (-273 deg. C). Since the volume of the
tire is essentially constant, and n and R are constants for the same
gas the ratios of temperature and pressure reduce to: P1/T1=P2/T2
Frank

 

[Edward Hayes]

I stand corrected and thank you. It has been a few years. Eddie