Tire pressure for winter storage
Team Owner
Joined: May 2001
Posts: 25,060
Likes: 1,265
From: Virginia
St. Jude Donor '11
Well I guess you are consistant in trying to find "inconsistency" in everything ET says ...many CF members including myself have followed what Bill has said over and over about tire pressure and benefitted greatly in our Vette performance, gas mileage and tire wear. Can't imagine why a bunch of numnuts here keep disagreeing with an engineer who actually helped develop some of the systems in the C5 and had first hand knowledge of the rest of the systems of the C5 Corvette...it amazes me that some shade tree wannabe mechanics in here would even want to argue with him...
anyway...carry on ET...
p.s....air molecules can and do escape through tire rubber...whoever disagrees is a flogging moron
Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
Personally in the North east where I live now , most roads are concrete,, and the road temps never get to 140 F... I adjust my temps to accommodate where I live.. trying to keep my tires at 30/31 psi Hot. I was giving an extreme case to which I did a study , while at Georgia Tech and found on many Georgia Highways that are black topped, which can be 30 degrees hotter then the same area with a concrete roadway..
Race Director
Joined: Mar 2003
Posts: 10,789
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From: Northern Illinois
Oldtimer
Drifting
Joined: Feb 2005
Posts: 1,643
Likes: 167
As I said in an earlier post, my tire pressure usually increases 3-4 psi when it's cold outside. My Cruze displays tire pressure for each tire when I check it. I typically see more of a pressure increase (4-7 psi) during the summer months. I'm no scientist, but it does seem that my tire pressure increases more when it's hot.
Last edited by thisMSGgood4me; Dec 2, 2014 at 11:36 PM.
Race Director
Joined: Mar 2003
Posts: 10,789
Likes: 894
From: Northern Illinois
Oldtimer
Drifting
Joined: Sep 2013
Posts: 1,320
Likes: 204
From: Calabash, NC
I've explained this hundreds of times in the last 13 years here. Cold air is dense, meaning the molecules are closer together. Spacing between the molecules shrinks in cold weather, and expands in hot weather.. as these molecules become closer together and the volume of total air decreases. That's why tire pressure increases when its hot and decreases whe its cold.
Consider a cubic foot of air... in that cubic foot of air, are millions of Oxygen and Nitrogen atoms.. some argon and hydrogen which makes moisture... ( H2O ) when the ambient temp is cold, the space between the molecule shrinks.. allowing more Nitrogen and Oxygen atoms to occupy the same space... this Cold ambient temp condition is mother natures super charger... it compresses the volume so the more oxygen can be added to the fuel misture withing the same volume. this is why you lose HP in hot weather, and get an increase in HP when its cold... Corrected dyno numbers use a correction factor od 1.8 Hp per ten degrees. so a decrease in temp from 90 degrees F to 20 degrees F. can yield a 12.5 hp gain in the winter over the summer at 90 F.
Back to the tires... I have said for many years you test your tire pressure when they are hot ( at operating temp ). this is the pressure they see when actually working.. this actual temp effects how the foot print reacts to driving conditions.. Its what NASCAR and Most Road course pit crews use to set their tire pressure.. IN a 500 mile race, track temps can vary by as much as 80 degrees.
IN a garage in Georgia on a cool cement floor in the morning ambient temps inside a tire at rest could be 50 degrees... now take that car out on a hot Georgia Blacktop on a 95+ day and the road temp can see 140 F at the surface.. that's a 90 degree variation.. a 30 PSI cold temp in the garage can easily see 38 psi when hot. that's too much pressure.
this is why you get poor performance and center wear on a tire that is overinflated.
I set my pressure for summer driving and for winter driving... in the winter in the North east. I set my in garage pressure to 32/34 psi so when they get out on a 20 degree roadway they are at 30 PSI
IN the summer when temps on the road can see 140.. I set my cold garage temps to 27/28 so they see 30 psi when they are actually performing.. Pit crews adjust tire pressure for actual performance and not for cold static non use.
BTW as I said, cold weather is Mother Natures supercharger compressing the air so more oxygen can get into the mix.. this is why your car seems to run better in the cold weather..
AS the air compresses that cubic foot of air increases its molecular structure because more air can occupy that same space, because its compressed. air is also compressed in cold weather in your tires that why you loose pressure in your tire, ( it doesn't leave the tire ) its just compressed.. when you add that 2 extra lbs of air to bring it back to 30 psi. that the amount of extra air you can add to the same space., More air in the fuel mix under the same flow rate will increase HP. ( the same principle used in a supercharger.
IM just offering a little automotive 101 here.. I really don't want to hear any more mentally challenge people dispute this fact. Take it or leave it.
I hope this will help some people understand the relationship between temperature and air pressure.. the ones that don't get it or don't believe it, I'm sorry.
Bill aka ET
Consider a cubic foot of air... in that cubic foot of air, are millions of Oxygen and Nitrogen atoms.. some argon and hydrogen which makes moisture... ( H2O ) when the ambient temp is cold, the space between the molecule shrinks.. allowing more Nitrogen and Oxygen atoms to occupy the same space... this Cold ambient temp condition is mother natures super charger... it compresses the volume so the more oxygen can be added to the fuel misture withing the same volume. this is why you lose HP in hot weather, and get an increase in HP when its cold... Corrected dyno numbers use a correction factor od 1.8 Hp per ten degrees. so a decrease in temp from 90 degrees F to 20 degrees F. can yield a 12.5 hp gain in the winter over the summer at 90 F.
Back to the tires... I have said for many years you test your tire pressure when they are hot ( at operating temp ). this is the pressure they see when actually working.. this actual temp effects how the foot print reacts to driving conditions.. Its what NASCAR and Most Road course pit crews use to set their tire pressure.. IN a 500 mile race, track temps can vary by as much as 80 degrees.
IN a garage in Georgia on a cool cement floor in the morning ambient temps inside a tire at rest could be 50 degrees... now take that car out on a hot Georgia Blacktop on a 95+ day and the road temp can see 140 F at the surface.. that's a 90 degree variation.. a 30 PSI cold temp in the garage can easily see 38 psi when hot. that's too much pressure.
this is why you get poor performance and center wear on a tire that is overinflated.
I set my pressure for summer driving and for winter driving... in the winter in the North east. I set my in garage pressure to 32/34 psi so when they get out on a 20 degree roadway they are at 30 PSI
IN the summer when temps on the road can see 140.. I set my cold garage temps to 27/28 so they see 30 psi when they are actually performing.. Pit crews adjust tire pressure for actual performance and not for cold static non use.
BTW as I said, cold weather is Mother Natures supercharger compressing the air so more oxygen can get into the mix.. this is why your car seems to run better in the cold weather..
AS the air compresses that cubic foot of air increases its molecular structure because more air can occupy that same space, because its compressed. air is also compressed in cold weather in your tires that why you loose pressure in your tire, ( it doesn't leave the tire ) its just compressed.. when you add that 2 extra lbs of air to bring it back to 30 psi. that the amount of extra air you can add to the same space., More air in the fuel mix under the same flow rate will increase HP. ( the same principle used in a supercharger.
IM just offering a little automotive 101 here.. I really don't want to hear any more mentally challenge people dispute this fact. Take it or leave it.
I hope this will help some people understand the relationship between temperature and air pressure.. the ones that don't get it or don't believe it, I'm sorry.
Bill aka ET
Looks like its time for a basic physics refresher:
PV=nRT
where:
P is the pressure of the gas
V is the volume of the gas
n is the amount of substance of gas (also known as number of moles)
R is the ideal, or universal, gas constant, equal to the product of the Boltzmann constant and the Avogadro constant.
T is the temperature of the gas
In out case with tires, V, n and R are constants so it does not matter. Simply speaking, what remains are Temperature and Pressure.
Temperature and pressure are directly proportional to each other with nR being the scaling factor.
The only variable is the real leakage (valve stem, rims, etc) and the microscopic leakage (which scientifically does occur but is not really measurable).
Bottom line is that one should keep an eye on their car when in storage and give it the same TLC as if it were the summer months.
Drifting
Joined: Sep 2013
Posts: 1,320
Likes: 204
From: Calabash, NC
About to head off to storage
I decided to keep the tires at 30psi. I measured the pressure with a swanky new gauge with a round dial and it told me that I had only 25psi. So I got out my new Slime kit and ran the compressor only (no slime) until it told me I had 30psi. But at the outset it told me I had 28 or so, and I only added about 2 psi. Unsure of all of this, I went to the store that sold me the Hankooks and they measured the pressure using one of those stick-style gauges. It said I was right at 30 psi. That was fine until the next morning when, just starting on my trip to the storage unit, I check the TPMs using the gauges on the dash, and it said my tires were at 28psi. What gauge should I believe? By the time I got to the storage unit my wife was in a big hurry to turn around and get home, so there was no chance to put more air in the tires. So there are there for 4 months at either 28 or 30 psi. I'll let you know in April if it survived.
Sorry about all that white stuff but the car looks pretty sweet against the backdrop.
Le Mans Master
Joined: Aug 2009
Posts: 5,197
Likes: 190
From: ALL governments are legalized mobsters, so doesn't matter where I live :(
I think someone needs to be the voice of reason. The OP asked a simple question which now seems to require a PhD to decipher the answer. What everyone said makes sense, but simply put, adding a couple of extra pounds to a tire before storage makes sense. Have a good day
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Drifting
Joined: Feb 2005
Posts: 1,643
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Team Owner
Joined: Mar 2001
Posts: 21,325
Likes: 3,841
From: small town in S.E Pa. PA
St. Jude Donor '03-'04
That's why I try to explain things in simple terms so people can understand it...posting formulas and technical jargon does not serve the average car enthusiast... that why I explain things the way I do... .. IM only here to help people understand things. Not to fluff my own bloomers.
Melting Slicks
Joined: Nov 2014
Posts: 3,399
Likes: 1,339
From: Havre de Grace Maryland
Simple is best
Welcome to the forum rrwirsi.. IM 70 years old, Please do not put my name in the same sentence with that poor misguided, clueless member.
As I've said for 13 years here on the Forum since retiring from GM
" Be careful who you listen too about a C5, on this forum "... Even stupid has an opinion.
Bill aka ET
As I've said for 13 years here on the Forum since retiring from GM
" Be careful who you listen too about a C5, on this forum "... Even stupid has an opinion.
Bill aka ET
Former Law Dawg Moderator
Joined: Jan 2005
Posts: 29,434
Likes: 96
From: Eads, Tennessee
CF St. Jude Co-Organizer
St. Jude Donor '05 thru '24
Enough of the back and forth bickering. If you find your posts removed it means your posts are violating the rules of the forum:
https://www.corvetteforum.com/forums...conflicts.html
https://www.corvetteforum.com/forums...conflicts.html
Burning Brakes
Joined: Mar 2014
Posts: 807
Likes: 239
Enough of the back and forth bickering. If you find your posts removed it means your posts are violating the rules of the forum:
https://www.corvetteforum.com/forums...conflicts.html
https://www.corvetteforum.com/forums...conflicts.html
Former Law Dawg Moderator
Joined: Jan 2005
Posts: 29,434
Likes: 96
From: Eads, Tennessee
CF St. Jude Co-Organizer
St. Jude Donor '05 thru '24
Your rules got violated 43 posts ago. Where you been? Give your rules some teeth and maybe folks will adhere. It didn't take me long to figure out the one constant in most of the the threads I have seen locked in the past. I wonder if you have picked up on it too. Just sayin.
For the time being this thread has gotten off track and is now closed for the time being.
Former Law Dawg Moderator
Joined: Jan 2005
Posts: 29,434
Likes: 96
From: Eads, Tennessee
CF St. Jude Co-Organizer
St. Jude Donor '05 thru '24
I'm reopening this thread and I have deleted posts that are in conflict with the rules regarding personal attack and online conflicts. Members are welcome to debate, but when it gets to the point of name calling, personal attacks, etc., it's just time to move on to another thread or topic.
Maybe giving vacations would be a better choice?
Maybe giving vacations would be a better choice?
Race Director
Joined: Mar 2003
Posts: 10,789
Likes: 894
From: Northern Illinois
Oldtimer
I've been on this forum almost 12 years and it never ceases to amaze me at how such simple topics can go sideways so quickly. I'll be the first to admit that I love to bust people's chops and have probably irritated a few people over the years. My goodness, we're talking tire pressure here. We're talking about cars. Nothing more. Nothing less. If the worst thing that happens to me today is having to worry about tire pressure, I consider myself an extremely fortunate man. I know a number of people who would give anything to be alive and on this this forum to debate tire air pressure, wax, oil or many of the other countless debates we get into here. We don't always agree on everything here, but let's keep things in prospective. There are more much serious things going on in this world and we're so blessed to have awesome cars that take us away from those things for a little while. Let's not be so hard on one another. After all, we share the same passion.
Team Owner
Joined: Mar 2001
Posts: 21,325
Likes: 3,841
From: small town in S.E Pa. PA
St. Jude Donor '03-'04
I've been on this forum almost 12 years and it never ceases to amaze me at how such simple topics can go sideways so quickly. I'll be the first to admit that I love to bust people's chops and have probably irritated a few people over the years. My goodness, we're talking tire pressure here. We're talking about cars. Nothing more. Nothing less. If the worst thing that happens to me today is having to worry about tire pressure, I consider myself an extremely fortunate man. I know a number of people who would give anything to be alive and on this this forum to debate tire air pressure, wax, oil or many of the other countless debates we get into here. We don't always agree on everything here, but let's keep things in prospective. There are more much serious things going on in this world and we're so blessed to have awesome cars that take us away from those things for a little while. Let's not be so hard on one another. After all, we share the same passion.
As far as being too serious and health issues.. well, many of my close friends here know how sick I am, and because I am so sick, I spend a lot of time here to take my mind off my very serious health issues.. Last year I was expected Not to be here this year... last years I spent 31 days in critical care, after surgery, being diagnosed with Cancer. IM not trying to create drama, here believe me, but as you can see IM here to help people,., and not be disrespected. So its the disrespect that drives the back and Forth.. Jim Willis ( savewave )knows of my health issues and told me that the moderators would be sensitive to personal attacks because with so many post , there are bound to be problems.. when the mods don't step in when people disrespect me.,.. I have to defend myself, and I will... so sorry for the drama...but I've invested thousands of hours here offering insider information on how this car was built.. things that you wont find in any book...and offering many hours of answering thousands and thousands of private message and open forum help questions.
Last edited by Evil-Twin; Dec 5, 2014 at 12:26 PM.
Thread Starter
Drifting
Joined: Feb 2014
Posts: 1,657
Likes: 195
From: Boxford Massachusetts
As a newcomer here, ET, i respect your experience, advice and opinions. I'm sure others here do as well. Don't be thrown off your horse by skeptics. Ignore them. By now the great weight of the advice that you have provided here gives you credibility that is not going to be eroded by the occasional doubter. Just don't get your blood pressure up or feel the need to defend yourself against all shots taken. People here know who's who . . . you don't have to remind us.