The Ford Barn

Bob Bidonde · 11-12-2023, 07:39 AM

The temperature on Long Island dropped into the low 40s over this past weekend. While preparing my Victoria for a Veteran's Day Parade, I noticed the its tires looked low. Due to the dropping temperatures, the tire pressure on my "A" dropped from 32PSIG to 26PSIG, so this post is a heads-up. If the temperature has dropped in your locale, check your tire pressure.
By the way, I run Universal Tires and the label on their sidewalls indicate their maximum load rating requires 32 PSIG, not Ford's 35 PSIG. I follow the tire tire's designated pressure.

jrelliott · 11-12-2023, 11:14 AM

It is Boyles law. P=VxT Pressure equals Volume times temperature. We live in the mountains and the temps between night and day can be over 40 degrees. Tire pressure low in the mornings and high in the afternoon. Thanks again for the heads up about tire pressure to those that do not notice.

Big hammer · 11-12-2023, 11:34 AM

Cold tire pressure vs hot tire pressure, on one of my modern car’s the door sticker for tire pressure had a cold pressure 35# and a hot tire pressure 39#. I’ve needed to check my A’s tire pressure while out and about last week I finally had a chance to check the pressure. This was after 70 mile drive, the hot pressure of 35# I added air to 39#, driving back on the same roads the car rode much softer? I believe the hard tire pressure now allowed the springs and shocks to work as they were designed !

nkaminar · 11-13-2023, 08:35 AM

Actually Boyle's Law is an extension of PV=nRT where P is absolute pressure, V is volume, n is the number of molecules in moles, R is the gas constant, and T is the absolute temperature.

Absolute zero is -460 degrees Fahrenheit. So the temperatures to compare are 75 F (535 absolute) to 32 F (492 absolute). So the absolute tire pressure would be 492/535=92.5% of the pressure at the higher temperature when it is freezing.

A flat tire still has an absolute pressure of 14.7 psi at sea level. Gage pressure is the absolute pressure minus the atmospheric pressure. A tire that reads 35 psi at sea level would read 49.7 psi in space.

This formula is what powers the car. The temperature increases during ignition.

There will be a pop quiz at 3 PM.

old31 · 11-13-2023, 09:12 AM

NK you made my head hurt

Oldbluoval · 11-13-2023, 09:15 AM

Sponsored Links (Register now to hide all advertisements)

Did A’’s not come with tire pressure indicator on the dash?
Maybe on deluxe models?? Lol

Benson · 11-13-2023, 09:43 AM

.....

Ruth · 11-13-2023, 10:00 AM

Quote:

Originally Posted by Bob Bidonde

The temperature on Long Island dropped into the low 40s over this past weekend. While preparing my Victoria for a Veteran's Day Parade, I noticed the its tires looked low.Due to the dropping temperatures, the tire pressure on my "A" dropped from 32F to 26F, so this post is a heads-up. If the temperature has dropped in your locale, check your tire pressure.
By the way, I run Universal Tires and the label on their sidewalls indicate their maximum load rating requires 32 PSIG, not Ford's 35 PSIG. I follow the tire tire's designated pressure.

How does tire pressure drop in degrees Fahrenheit??

katy · 11-13-2023, 10:20 AM

Quote:

Originally Posted by nkaminar

There will be a pop quiz at 3 PM.

Sorry, can't make it, that's my nap time.

nkaminar · 11-14-2023, 07:59 AM

Ruth, You have to convert to absolute temperature by adding 460 to the degrees in Fahrenheit and then find the ratio by dividing one by the other. The absolute temperature scale using Fahrenheit intervals is called the Rankine scale. Here at my house it is really cold this morning, 497 degrees Rankine.

Bob Bidonde · 11-14-2023, 08:06 AM

Oops! I goofed re temps in degrees F. Should be PSIG. Thanks for catching my error. I fixed the original post. You all are sharp!

updraught · 11-14-2023, 08:14 PM

https://www.coopertires.com.au/tyres...old%20pressure.

The 4 PSI rule is a thing here for radials. From cold they should raise 4 PSI when hot.
Interesting the warning about tyre placards that have pressures of less than 30 PSI from factory.
My wife's Subaru came with a sheet saying to ignore the factory pressures and use 34 PSI.

katy · 11-14-2023, 08:53 PM

What temperature is cold? Here it can be anywhere from -40°C to 0°C

updraught · 11-14-2023, 08:58 PM

Quote:

Originally Posted by katy

What temperature is cold? Here it can be anywhere from -40°C to 0°C

I think you need to move to a warmer climate and then check your pressures.

11-12-2023, 07:39 AM	#1
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,466	Jack Frost & The Cold Affect Tire Pressure The temperature on Long Island dropped into the low 40s over this past weekend. While preparing my Victoria for a Veteran's Day Parade, I noticed the its tires looked low. Due to the dropping temperatures, the tire pressure on my "A" dropped from 32PSIG to 26PSIG, so this post is a heads-up. If the temperature has dropped in your locale, check your tire pressure. By the way, I run Universal Tires and the label on their sidewalls indicate their maximum load rating requires 32 PSIG, not Ford's 35 PSIG. I follow the tire tire's designated pressure. __________________ Bob Bidonde Last edited by Bob Bidonde; 11-14-2023 at 08:06 AM.

11-12-2023, 11:14 AM	#2
jrelliott Senior Member Join Date: May 2010 Location: Pine, AZ Posts: 794	Re: Jack Frost & The Cold Affect Tire Pressure It is Boyles law. P=VxT Pressure equals Volume times temperature. We live in the mountains and the temps between night and day can be over 40 degrees. Tire pressure low in the mornings and high in the afternoon. Thanks again for the heads up about tire pressure to those that do not notice.

11-12-2023, 11:34 AM	#3
Big hammer Senior Member Join Date: Jun 2014 Location: Land of Lincoln Posts: 3,131	Re: Jack Frost & The Cold Affect Tire Pressure Cold tire pressure vs hot tire pressure, on one of my modern car’s the door sticker for tire pressure had a cold pressure 35# and a hot tire pressure 39#. I’ve needed to check my A’s tire pressure while out and about last week I finally had a chance to check the pressure. This was after 70 mile drive, the hot pressure of 35# I added air to 39#, driving back on the same roads the car rode much softer? I believe the hard tire pressure now allowed the springs and shocks to work as they were designed ! __________________ Don't force it with a little hammer tap, tap, tap get a bigger hammer tap done

11-13-2023, 08:35 AM	#4
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Jack Frost & The Cold Affect Tire Pressure Actually Boyle's Law is an extension of PV=nRT where P is absolute pressure, V is volume, n is the number of molecules in moles, R is the gas constant, and T is the absolute temperature. Absolute zero is -460 degrees Fahrenheit. So the temperatures to compare are 75 F (535 absolute) to 32 F (492 absolute). So the absolute tire pressure would be 492/535=92.5% of the pressure at the higher temperature when it is freezing. A flat tire still has an absolute pressure of 14.7 psi at sea level. Gage pressure is the absolute pressure minus the atmospheric pressure. A tire that reads 35 psi at sea level would read 49.7 psi in space. This formula is what powers the car. The temperature increases during ignition. There will be a pop quiz at 3 PM. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past. Last edited by nkaminar; 11-13-2023 at 09:04 AM.

11-13-2023, 09:12 AM	#5
old31 Senior Member Join Date: Jan 2016 Posts: 2,098	Re: Jack Frost & The Cold Affect Tire Pressure NK you made my head hurt

11-13-2023, 09:15 AM	#6
Oldbluoval Senior Member Join Date: Jun 2015 Location: Signal Mtn, TN (SE TN) Posts: 2,371	Re: Jack Frost & The Cold Affect Tire Pressure Sponsored Links (Register now to hide all advertisements) Did A’’s not come with tire pressure indicator on the dash? Maybe on deluxe models?? Lol

11-13-2023, 09:43 AM	#7
Benson Senior Member Join Date: May 2010 Posts: 2,597	Re: Jack Frost & The Cold Affect Tire Pressure ..... Last edited by Benson; 11-17-2023 at 01:53 AM.

11-14-2023, 07:59 AM	#10
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Jack Frost & The Cold Affect Tire Pressure Ruth, You have to convert to absolute temperature by adding 460 to the degrees in Fahrenheit and then find the ratio by dividing one by the other. The absolute temperature scale using Fahrenheit intervals is called the Rankine scale. Here at my house it is really cold this morning, 497 degrees Rankine. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

11-14-2023, 08:06 AM	#11
Bob Bidonde Senior Member Join Date: May 2010 Location: Long Island, NY Posts: 3,466	Re: Jack Frost & The Cold Affect Tire Pressure Oops! I goofed re temps in degrees F. Should be PSIG. Thanks for catching my error. I fixed the original post. You all are sharp! __________________ Bob Bidonde

11-14-2023, 08:14 PM	#12
updraught Senior Member Join Date: Feb 2015 Location: Australia Posts: 1,970	Re: Jack Frost & The Cold Affect Tire Pressure https://www.coopertires.com.au/tyres...old%20pressure. The 4 PSI rule is a thing here for radials. From cold they should raise 4 PSI when hot. Interesting the warning about tyre placards that have pressures of less than 30 PSI from factory. My wife's Subaru came with a sheet saying to ignore the factory pressures and use 34 PSI.

11-14-2023, 08:53 PM	#13
katy Senior Member Join Date: Jun 2015 Location: Red Deer, Alberta Posts: 5,044	Re: Jack Frost & The Cold Affect Tire Pressure What temperature is cold? Here it can be anywhere from -40°C to 0°C __________________ If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn!