Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 10-25-2021, 04:06 PM   #85
Senior Member
 
RoadTrip2084's Avatar
 
Monaco Owners Club
RV Trip Wizard
Join Date: Sep 2021
Location: Airdrie, AB
Posts: 201
Quote:
Originally Posted by BigBillSD View Post
I have, but so far only Michelin mentions it. And now that I look on their site for a few minutes, I have not found it. Michelin gave us a handout during an escapees seminar, and theirs said tire pressures should be corrected to 68 degrees on what I remember was an official glossy Michelin handout. Its too bad that this last year I was so bored the first couple months I started purging the house of unneeded crap. All that old paperwork went into the recycle bin. I don't use Michelin's anyway.

I only top up my tires when its around 70 degrees in the morning. They have about 50k miles now, and will be aging out in the next couple years. -Bill
The Caterpillar reference I included back in https://www.irv2.com/forums/f258/adj...ml#post5956845 mentions

"The table shows the correct pressures for tires that are inflated in an area with a temperature
of 18 to 21C (64 to 70F)." So that would be considered the default temp. range for cold tire inflation.
RoadTrip2084 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 10-25-2021, 04:44 PM   #86
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 1,073
Quote:
Originally Posted by RoadTrip2084 View Post
The Caterpillar reference I included back in https://www.irv2.com/forums/f258/adj...ml#post5956845 mentions

"The table shows the correct pressures for tires that are inflated in an area with a temperature
of 18 to 21C (64 to 70F)." So that would be considered the default temp. range for cold tire inflation.
Im sorry - I do not see an interpretation there that implies that you should then adjust the pressures in the tires at colder temperatures so that if the tires were to hit those "reference" temperatures then their pressures would correspond to the pressures they used at those temperatures.. sorry - it does not make sense (physically and mechanically) that at much colder temperatures you would inflate the tires to a LOWER pressure - which would then be unable to support the load (which has not changed with temperature) without overly flexing. sorry .... but to me that is a totally incorrect, and dangerous, interpretation of what they are saying in that publication.
__________________
- 2017 Newmar London Aire -
MN_Traveler is offline   Reply With Quote
Old 10-25-2021, 05:39 PM   #87
Senior Member
 
BigBillSD's Avatar
 
Join Date: Oct 2016
Location: San Diego
Posts: 739
Quote:
Originally Posted by Kid Gloves View Post
Perhaps Michelin punted on the idea of a temperature correction factor after realizing that a large percentage of owners cant figure out how to properly inflate their tires when give the simplest of instructions.

Good Point! It says 120 lbs on my tires, that's the pressure I should run.. Right. -Bill
__________________
2006 Allegro Bus 40 QDP 8.9L 1.5kw roof Solar, 2@ Victron 50amp MPPT, 712BMV, SBS, CerboGX, Vmspec, 8.7kw Renogy LiFePo4, 19' GE RR, MS2812, 400w Suitcase & Victron 100/30 MPPT
BigBillSD is offline   Reply With Quote
Old 10-25-2021, 05:58 PM   #88
Senior Member
 
Ford Super Duty Owner
Join Date: Nov 2018
Location: Frisco, Tx.
Posts: 312
"All tire manufactures state that you should check your tire pressure in the morning before the vehicle has moved more than a mile."

+++++

That said, colder air is more dense. A tire that is carrying thousands of pounds needs adequate pressure to perform as designed.

If you are too lazy to fill them or just ignorant , it is at your own peril.

__________________
2021 Newmar BS3014
2X Ebikes on the back
Almost enough solar
Jacjetlag is offline   Reply With Quote
Old 10-25-2021, 06:05 PM   #89
Member
 
Join Date: Jan 2015
Posts: 65
Quote:
Originally Posted by Domo View Post
No, you don't adjust your pressure during the day. Overinflation changes the profile of your tires and affects performance - at least according to the Michelin folks I've spoken to on three occasions - but some folks don't seem to believe them.

Here's a good read about tires from a manufacturer;
I am surprised that it took so long for your comment's arrival to address the issue of PHYSICS. It seems the prevailing opinions are to forget physics and stick to the number. That air pressure in tires decrease about 1 psi per 10 degrees; and that the recommended pressure is at 20 deg C/68 F means that seeing a tire pressure that was at 65 when the temperature was 68 in the morning and rose to 71 when the out of the sun ambient was at 90 is quite normal. Similarly they will drop from 65 to 62 around freezing. Reinflating them to 65 is over inflating them.

There is a consensus that irrespective of the temperature there is a pressure below which you should not run the tire in order to retain bead integrity and that is recommended by Michelin and Continental ( the only OEMs that I have seen this discussed ) at 75% of the rated temperature.

However this is not an exact science and also one where most of the science is retained by the OEMs to avoid liability. But it does raise the question as to how impaired a tire becomes if the pressure is 5% over or under the tire maximum at maximum weight? I do not think anyone knows, not even the OEMs. So for some this will be a holier than thou life's work to maintain the "perfect" pressure while for others, if it will take a good kick, its ok.
vlamgat is offline   Reply With Quote
Old 10-25-2021, 07:06 PM   #90
Senior Member
 
RoadTrip2084's Avatar
 
Monaco Owners Club
RV Trip Wizard
Join Date: Sep 2021
Location: Airdrie, AB
Posts: 201
Quote:
Originally Posted by MN_Traveler View Post
Im sorry - I do not see an interpretation there that implies that you should then adjust the pressures in the tires at colder temperatures so that if the tires were to hit those "reference" temperatures then their pressures would correspond to the pressures they used at those temperatures.. sorry - it does not make sense (physically and mechanically) that at much colder temperatures you would inflate the tires to a LOWER pressure - which would then be unable to support the load (which has not changed with temperature) without overly flexing. sorry .... but to me that is a totally incorrect, and dangerous, interpretation of what they are saying in that publication.
I think you're confused. The chart below the text shows the adjusted cold temp. tire pressure you should use for the equiv. normal cold tire pressure if you're dealing with COLD temps (32f and below). In each case the recommended pressure is higher than the default pressure.
RoadTrip2084 is offline   Reply With Quote
Old 10-25-2021, 07:28 PM   #91
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 1,073
Quote:
Originally Posted by RoadTrip2084 View Post
I think you're confused. The chart below the text shows the adjusted cold temp. tire pressure you should use for the equiv. normal cold tire pressure if you're dealing with COLD temps (32f and below). In each case the recommended pressure is higher than the default pressure.
Ok - apologies. What the manual is saying (and this is a quote) is "tires inflated in a warm shop will be underinflated in cold temperatures". This is correct and makes sense. again - apologies.

What others are saying is exactly the opposite of what the linked manual is saying. THEY are saying that you should always maintain an inflation equivalent to what the tire contents would be (pressure wise) if they were shifted in temperature to some reference temp (like 68F). That is invalid, unsafe, and actually exactly opposite of what the linked manual is saying.
__________________
- 2017 Newmar London Aire -
MN_Traveler is offline   Reply With Quote
Old 10-25-2021, 07:37 PM   #92
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 1,073
Quote:
Originally Posted by vlamgat View Post
I Similarly they will drop from 65 to 62 around freezing. Reinflating them to 65 is over inflating them.

.
I am not quite positive what you are trying to say .... but if you are saying, as I think you are, that when the temperature is low, that you should NOT reinflate the tires to (as in your example) to, say, 65 .... that is just plain wrong and dangerous. See my just previous posting (where I apologized for misinterpreting what the poster was saying), then go read the quote I give in that posting, then go read the manual that for which that poster gave a link. it explicitly says that tires inflated in a warm shop (say 68F) will be underinflated when taken out into cold/freezing conditions. So ... if you are saying that if you actually have the tires out in freezing conditions, and you are reading a pressure that is below the minimum inflation for the load, that you should NOT reinflate the tires .... That is incorrect.

And to say that the manufacturers do not have any idea of what pressures cause damage to the tires (it is that damage, NOT unseating the bead as you apparently incorrectly claim) - that is also very sorely incorrect.

It is called engineering "testing".

This time I am truly and completely done with this thread.
__________________
- 2017 Newmar London Aire -
MN_Traveler is offline   Reply With Quote
Old 10-25-2021, 08:04 PM   #93
Junior Member
 
Fleetwood Owners Club
Join Date: Oct 2021
Posts: 3
Typically how many years can you get out of a tire even if the tread is still good?
Cactusbu11 is offline   Reply With Quote
Old 10-25-2021, 08:39 PM   #94
Senior Member
 
Join Date: Jan 2021
Posts: 1,905
Quote:
Originally Posted by BigBillSD View Post
Good Point! It says 120 lbs on my tires, that's the pressure I should run.. Right. -Bill
Well heck, if it says 120 right there on the tire, that must be the correct pressure, for you, and everyone else who puts that tire on their vehicle.

Brilliant!
Kid Gloves is offline   Reply With Quote
Old 10-25-2021, 10:04 PM   #95
NXR
Senior Member
 
NXR's Avatar
 
Join Date: Mar 2019
Posts: 3,433
Adjust tire pressure for cold weather??

But...when air gets colder it gets more dense and can support more weight. That's the concept of Density Altitude in aviation and why aircraft can take off in a shorter distance when it's cold than what it's hot.

https://www.faasafety.gov/files/gsla...%20branded.pdf

So if colder air is more dense why do we need to add pressure to tires when it gets colder? If the air in a tire truly is what supports the weight, shouldn't more dense air (cold air) be able to support more weight and not less?

Ray
__________________
2020 Forest River Georgetown GT5 34H5
NXR is offline   Reply With Quote
Old 10-25-2021, 10:59 PM   #96
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 1,073
Quote:
Originally Posted by NXR View Post
But...when air gets colder it gets more dense and can support more weight. That's the concept of Density Altitude in aviation and why aircraft can take off in a shorter distance when it's cold than what it's hot.

https://www.faasafety.gov/files/gsla...%20branded.pdf

So if colder air is more dense why do we need to add pressure to tires when it gets colder? If the air in a tire truly is what supports the weight, shouldn't more dense air (cold air) be able to support more weight and not less?

Ray
Ok .... for a clearly serious, and actually very insightful question, I will try to answer .... because it might help cut through some of the misinformation on this thread.

Ray - this is actually a really good question - and the answer is that this is really mixing two very different aspects of physics.

A plane wing flies because of two things: the curved top of the wing which produces lower pressure on the top of the wing than on the bottom (the Bernoulli effect - which is is a pressure thing and has nothing to do with density), and the angle of attack of the wing (where, when the front of the wing is tilted upward and the wing pushed forward, air hitting the bottom of the wing is deflected downward, which exerts an upward force on the wing (newtons third law - when an object exerts a force on another object, the second object exerts an equal and opposit force on the first - strictly a density/mass thing, and has nothing to do with pressure).

Your density altitude thing is mostly a result of the angle of attack of a wing allowing it to "push" downward on the air - the denser (colder) the air, the stronger the upward force (because the air molecules are closer together, and the wing pushes more molecules downward for a given amount of forward motion .... kind of like throwing downward two baseballs versus one ... it takes more force to throw down two of them.

Inside a tire, there is no such "pushing" of air, and so its density becomes a non-issue. The ONLY thing acting inside a tire is the pressure the air exerts on the tread, walls, and rim of the tire. This works because a given pressure pushing on the tire "stiffens" the tire, and limits how much the sidewalls of the tire will deflect for a given load. If the pressure is lower, the tire sidewalls are not held stiffly in place, and can deflect more (very much like a very underinflated balloon is easy to squeeze and deform, but a highly inflated balloon is very stiff, and difficult to deform - it can support more weight without deforming.

To understand pressure - you really need to understand statistical thermodynamics .... but the simple explanation is that pressure is the result of lots and lots of gas molecules hitting the inside of the tire .... it is nothing more than that. It is the summation over time of many, many small "balls" (molecules) each with very very small mass and momentum hitting a wall. So .... the fewer the number of molecules inside the tire (like letting air out of the tire), the fewer will be hitting the wall in a given time, and the pressure is lower (the opposite is true when you add air to the tire.

As for temperature - it turns out that the speed a gas molecule flies through space is directly dependent on the temperature (the maxwell-boltzmann distribution). So for a tire with a certain amount of air in it, if the temperature goes down, the speed that the gas molecules are moving at goes down, and they each hit the inside of the tire with less momentum - and the pressure (and thus stiffness of the tire) goes down - for a given amount of weight on the tire, the tire deforms more. The tire may technically be supporting the weight, but upon each revolution it deforms more than if it were supported by a higher pressure - and it is this ongoing increased amount of deformation that causes increased stress and damage to the tire.
__________________
- 2017 Newmar London Aire -
MN_Traveler is offline   Reply With Quote
Old 10-26-2021, 06:40 AM   #97
Senior Member
 
Join Date: Jan 2021
Posts: 1,905
Thanks for coming back. Again.

So, would an airplane be able to take off in an even shorter distance, if it were inside a tire filled with compressed air?
Kid Gloves is offline   Reply With Quote
Old 10-26-2021, 07:54 AM   #98
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 1,073
Quote:
Originally Posted by Kid Gloves View Post
Thanks for coming back. Again.



So, would an airplane be able to take off in an even shorter distance, if it were inside a tire filled with compressed air?


Lol. I guess. Would take a pretty big tire though
__________________
- 2017 Newmar London Aire -
MN_Traveler is offline   Reply With Quote
Reply

Tags
cold weather, tire, tire pressure



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Cold cold cold RVific Newmar Owner's Forum 10 12-24-2020 06:44 PM
Tire extension to adjust air in rear outer tire jarata Class A Motorhome Discussions 9 02-01-2020 10:23 AM
Bounder: Cold (Really Cold) Weather RV'ing Bounderoo Fleetwood Owner's Forum 15 10-31-2018 02:02 PM
Cold weather tire pressure Roscott Newmar Owner's Forum 31 12-18-2014 05:08 AM
Cold Weather Camping.....No, Really Cold Weather Camping arkaussie Winnebago Industries Owner's Forum 14 03-08-2007 01:44 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 11:38 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2022, vBulletin Solutions, Inc.