tire pressure

Assuming all things being equal, if it's 34 degrees and all four tires read
25 psi what approx. was the tire pressure when the temperature was 68
degrees? Is there a simple way to judge the accuracy of one's tire gauge?
I've asked my town's weights and measures person when I happened to see him
checking the fuel pumps at a gas station and he said he didn't have any way
to check pressure gauges. The one I carry with me in my trunk has a flexible
braided hose and a brass gauge with a bleeder.

mark_

"mark_digital©" <976XXX@nospam.net> wrote in message
news:1a2dnbhjrY8bwZXZRVn-qA@comcast.com...[color=blue]
> Assuming all things being equal, if it's 34 degrees and all four tires
> read 25 psi what approx. was the tire pressure when the temperature was 68
> degrees? Is there a simple way to judge the accuracy of one's tire gauge?
> I've asked my town's weights and measures person when I happened to see
> him checking the fuel pumps at a gas station and he said he didn't have
> any way to check pressure gauges. The one I carry with me in my trunk has
> a flexible braided hose and a brass gauge with a bleeder.
>
> mark_[/color]

Well, when Mark gets serious, he REALLY gets serious!!

Seems to me I recall something about 4 PSI, but then, I saw little green
Martians, too...

I think BGM posted something about this in the spring last year, and there
are tables on the Interenet to help calculate this, if not an actual
calculator somewhere.

As Tegger used to say "google is your friend!"

"mark_digital©" <976XXX@nospam.net> wrote in message
news:1a2dnbhjrY8bwZXZRVn-qA@comcast.com...[color=blue]
> Assuming all things being equal, if it's 34 degrees and all four tires
> read 25 psi what approx. was the tire pressure when the temperature was 68
> degrees? Is there a simple way to judge the accuracy of one's tire gauge?
> I've asked my town's weights and measures person when I happened to see
> him checking the fuel pumps at a gas station and he said he didn't have
> any way to check pressure gauges. The one I carry with me in my trunk has
> a flexible braided hose and a brass gauge with a bleeder.
>
> mark_[/color]

25 psi is way too low no matter what the ambient temperature is. There is
no simple way to judge the accuracy of one's gauge, but the outlet pressure
gauge on my compressor matches the gauge on my Wilton tire inflator, which
matches the gauge on my pencil-type tire pressure gauge. That being the
case, I just use the gauge on my tire inflator.

For street use, 1 or 2 psi does not make a huge difference. The trick is to
make sure that all 4 tires are inflated evenly, or if the vehicle
manufacturer calls for higher pressure for the rear tires, that the
difference between the front and the rears are correct. For most passenger
cars, I recommend 3 or 4 psi higher than factory recommended for longer tire
life and fuel economy.
--

Ray O
(correct punctuation to reply)

mark_digital© wrote:[color=blue]
> Assuming all things being equal, if it's 34 degrees and all four tires read
> 25 psi what approx. was the tire pressure when the temperature was 68
> degrees? Is there a simple way to judge the accuracy of one's tire gauge?
> I've asked my town's weights and measures person when I happened to see him
> checking the fuel pumps at a gas station and he said he didn't have any way
> to check pressure gauges. The one I carry with me in my trunk has a flexible
> braided hose and a brass gauge with a bleeder.
>
> mark_[/color]

I can't think of any practical way to check the accuracy of your gauge,
but I can answer your first question.

At typical tire pressures and outdoor temperatures we can assume that
air will behave as an ideal gas. As such at constant volume, P2/P1 =
T2/T1, where T is the absolute temperature measured in Rankine (F+460).

In your case, (P2)/(25 psi) = (68+460)/(34+460) => P2 = 26.7 psi

<bcattwood@gmail.com> wrote in message
news:1141405085.454531.257200@t39g2000cwt.googlegroups.com...
mark_digital© wrote:[color=blue]
> Assuming all things being equal, if it's 34 degrees and all four tires
> read
> 25 psi what approx. was the tire pressure when the temperature was 68
> degrees? Is there a simple way to judge the accuracy of one's tire gauge?
> I've asked my town's weights and measures person when I happened to see
> him
> checking the fuel pumps at a gas station and he said he didn't have any
> way
> to check pressure gauges. The one I carry with me in my trunk has a
> flexible
> braided hose and a brass gauge with a bleeder.
>
> mark_[/color]

I can't think of any practical way to check the accuracy of your gauge,
but I can answer your first question.

At typical tire pressures and outdoor temperatures we can assume that
air will behave as an ideal gas. As such at constant volume, P2/P1 =
T2/T1, where T is the absolute temperature measured in Rankine (F+460).

In your case, (P2)/(25 psi) = (68+460)/(34+460) => P2 = 26.7 psi



Yeah! What he said! ;)

Hachiroku wrote:
[color=blue]
>
> I can't think of any practical way to check the accuracy of your gauge,
> but I can answer your first question.[/color]

The following web site claims that good tire dealers have a "master
gauge," whatever that is, and can check your tire gauge....

I'll ask next time I'm in my local shop, which is usually once every
couple of months...

timb...@mailcity.com wrote:[color=blue]
> Hachiroku wrote:
>[color=green]
> >
> > I can't think of any practical way to check the accuracy of your gauge,
> > but I can answer your first question.[/color]
>
> The following web site claims that good tire dealers have a "master
> gauge," whatever that is, and can check your tire gauge....
>
> I'll ask next time I'm in my local shop, which is usually once every
> couple of months...[/color]

OPPS, forgot the URL:

[url]http://www.retread.org/Inflation/index.cfm/ID/179.htm[/url]

"Hachiroku" <Trueno@ae86.GTS> wrote in message
news:RiZNf.2$ci1.0@trndny08...[color=blue]
> Well, when Mark gets serious, he REALLY gets serious!![/color]

Really? I'm much more relaxed now than ever.

What happened to a retired truck driver who went by the name Philip? and was
a regular in this group? Did he change his name or just doesn't frequent
this group?

"mark_digital©" <976XXX@nospam.net> wrote in message
news:ueKdnYgJK_GCQJXZRVn-pg@comcast.com...[color=blue]
>
> "Hachiroku" <Trueno@ae86.GTS> wrote in message
> news:RiZNf.2$ci1.0@trndny08...[color=green]
>> Well, when Mark gets serious, he REALLY gets serious!![/color]
>
> Really? I'm much more relaxed now than ever.
>
> What happened to a retired truck driver who went by the name Philip? and
> was a regular in this group? Did he change his name or just doesn't
> frequent this group?[/color]

I get occasional e-mails from him but I don't know whether he is lurking or
not frequenting this group.
--

Ray O
(correct punctuation to reply)

On 3 Mar 2006 09:45:53 -0800, [email]timbirr@mailcity.com[/email] wrote:
[color=blue]
>
>timb...@mailcity.com wrote:[color=green]
>> Hachiroku wrote:
>>[color=darkred]
>> >
>> > I can't think of any practical way to check the accuracy of your gauge,
>> > but I can answer your first question.[/color]
>>
>> The following web site claims that good tire dealers have a "master
>> gauge," whatever that is, and can check your tire gauge....
>>
>> I'll ask next time I'm in my local shop, which is usually once every
>> couple of months...[/color]
>
>OPPS, forgot the URL:
>
>[url]http://www.retread.org/Inflation/index.cfm/ID/179.htm[/url][/color]

And if you want to get totally paranoid about how accurate your
pencil gauge is, you can make a calibrator for yourself and you can
use it anytime the mood strikes you.

You can order a +/- 1% pressure gauge with a NIST traceable
calibration certificate for under $40 (McMaster-Carr 3543K21 2-1/2"
dial bottom connection)

After that, all you need is a 1/4" pipe tee, a male Schrader to male
pipe thread adapter, and a male disconnect plug that fits your shop
air piping system (or the output of a portable compressor) after the
regulator, a reducing bushing or two (the Schrader's are usually 1/8"
NPT and the gauges and air plug 1/4" NPT) and a little Teflon tape to
put it all together with.

You set the compressed air source regulator to 10, 20, 30, 50 pounds
on the calibrated gauge, plug the pencil gauge under test onto the
Schrader, and compare the two readings. Bada-Bing.

You can make little labels for the pencil gauges saying "Reads 5 PSI
High" if you can't remember.

And every 5 or 10 years you pack your calibration set securely in a
box and send the whole thing off to a Metrology Lab with a ($20) bill,
and they check it for accuracy (adjust as needed) and give you another
(X)-year calibration certificate.

(If you make friends at the lab, just put a Six-pack or two of their
favorite libation in the box.)

I'll build myself one, but I'll scrounge for a Mil-Surplus 6" gauge
that you can see a flea sneeze on - the calibration fee would be
nothing compared to what they want for a new one... ($400 and up.)

--<< Bruce >>--

--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
5737 Kanan Rd. #359, Agoura CA 91301 (818) 889-9545
Spamtrapped address: Remove the python and the invalid, and use a net.

"Bruce L. Bergman" <blPYTHONbergman@earthlink.invalid> wrote in message
news:a0di025i9i26pk30b5kr41ieqm35j4hhr8@4ax.com...[color=blue]
> On 3 Mar 2006 09:45:53 -0800, [email]timbirr@mailcity.com[/email] wrote:
>[color=green]
>>
>>timb...@mailcity.com wrote:[color=darkred]
>>> Hachiroku wrote:
>>>
>>> >
>>> > I can't think of any practical way to check the accuracy of your
>>> > gauge,
>>> > but I can answer your first question.
>>>
>>> The following web site claims that good tire dealers have a "master
>>> gauge," whatever that is, and can check your tire gauge....
>>>
>>> I'll ask next time I'm in my local shop, which is usually once every
>>> couple of months...[/color]
>>
>>OPPS, forgot the URL:
>>
>>[url]http://www.retread.org/Inflation/index.cfm/ID/179.htm[/url][/color]
>
> And if you want to get totally paranoid about how accurate your
> pencil gauge is, you can make a calibrator for yourself and you can
> use it anytime the mood strikes you.
>
> You can order a +/- 1% pressure gauge with a NIST traceable
> calibration certificate for under $40 (McMaster-Carr 3543K21 2-1/2"
> dial bottom connection)
>
> After that, all you need is a 1/4" pipe tee, a male Schrader to male
> pipe thread adapter, and a male disconnect plug that fits your shop
> air piping system (or the output of a portable compressor) after the
> regulator, a reducing bushing or two (the Schrader's are usually 1/8"
> NPT and the gauges and air plug 1/4" NPT) and a little Teflon tape to
> put it all together with.
>
> You set the compressed air source regulator to 10, 20, 30, 50 pounds
> on the calibrated gauge, plug the pencil gauge under test onto the
> Schrader, and compare the two readings. Bada-Bing.
>
> You can make little labels for the pencil gauges saying "Reads 5 PSI
> High" if you can't remember.
>
> And every 5 or 10 years you pack your calibration set securely in a
> box and send the whole thing off to a Metrology Lab with a ($20) bill,
> and they check it for accuracy (adjust as needed) and give you another
> (X)-year calibration certificate.
>
> (If you make friends at the lab, just put a Six-pack or two of their
> favorite libation in the box.)
>
> I'll build myself one, but I'll scrounge for a Mil-Surplus 6" gauge
> that you can see a flea sneeze on - the calibration fee would be
> nothing compared to what they want for a new one... ($400 and up.)
>
> --<< Bruce >>--
>
>[/color]
Since my pencil gauge, compressor regulator, and Milton gauge all agree, I
think I'll take the really cheap way out and continue to trust the Milton
gauge and just overfill by 5 PSI. ;-)
--

Ray O
(correct punctuation to reply)

Does tigger not say this anymore?? is he alright???


--
Stephen W. Hansen
ASE Certified Master Automobile Technician
ASE Automobile Advanced Engine Performance
ASE Undercar Specialist

[url]http://autorepair.about.com/cs/troubleshooting/l/bl_obd_main.htm[/url]
[url]http://www.troublecodes.net/technical/[/url]

"Hachiroku" <Trueno@ae86.GTS> wrote in message
news:RiZNf.2$ci1.0@trndny08...[color=blue]
>
> "mark_digital©" <976XXX@nospam.net> wrote in message
> news:1a2dnbhjrY8bwZXZRVn-qA@comcast.com...[color=green]
>> Assuming all things being equal, if it's 34 degrees and all four tires
>> read 25 psi what approx. was the tire pressure when the temperature was
>> 68 degrees? Is there a simple way to judge the accuracy of one's tire
>> gauge? I've asked my town's weights and measures person when I happened
>> to see him checking the fuel pumps at a gas station and he said he didn't
>> have any way to check pressure gauges. The one I carry with me in my
>> trunk has a flexible braided hose and a brass gauge with a bleeder.
>>
>> mark_[/color]
>
> Well, when Mark gets serious, he REALLY gets serious!!
>
> Seems to me I recall something about 4 PSI, but then, I saw little green
> Martians, too...
>
> I think BGM posted something about this in the spring last year, and there
> are tables on the Interenet to help calculate this, if not an actual
> calculator somewhere.
>
> As Tegger used to say "google is your friend!"
>
>
>[/color]

On Sat, 04 Mar 2006 16:33:17 GMT, "Stephen H" <hansensw@hotmail.com>
wrote:
[color=blue]
>Does tigger not say this anymore?? is he alright???[/color]

He is fine....

and it is Tegger

--

Scott in Florida

somione movid my i and e on thi kiyboard

Stivi


"Scott in Florida" <MoveOn@outa.here> wrote in message
news:oltj021joivlpc9nedak2l35g6e71lcrfq@4ax.com...[color=blue]
> On Sat, 04 Mar 2006 16:33:17 GMT, "Stephen H" <hansensw@hotmail.com>
> wrote:
>[color=green]
>>Does tigger not say this anymore?? is he alright???[/color]
>
> He is fine....
>
> and it is Tegger
>
> --
>
> Scott in Florida[/color]

On Fri, 3 Mar 2006 10:10:53 -0500, mark_digital© <976XXX@nospam.net>
wrote:
[color=blue]
>Assuming all things being equal, if it's 34 degrees and all four tires read
>25 psi what approx. was the tire pressure when the temperature was 68
>degrees? Is there a simple way to judge the accuracy of one's tire gauge?
>I've asked my town's weights and measures person when I happened to see him
>checking the fuel pumps at a gas station and he said he didn't have any way
>to check pressure gauges. The one I carry with me in my trunk has a flexible
>braided hose and a brass gauge with a bleeder.
>
>mark_[/color]

whatever it is, 25 psi is way too low. Keep it at 35 psi cold and
you're always good. Right now you are using more gas, and wearing out
the tires faster.