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

Go Back   Keystone RV Forums > Keystone Tech Forums > Tires, Tires, Tires!
Click Here to Login

Reply
 
Thread Tools Display Modes
 
Old 09-30-2021, 04:56 PM   #41
jasin1
Senior Member
 
jasin1's Avatar
 
Join Date: Aug 2020
Location: Upper Chesapeake Bay
Posts: 4,412
Quote:
Originally Posted by Javi View Post
I got a TS something or 'other 507 something and I turn it on to see if my tires are somewhere between 105 psi and 115 psi... yep... I'm good

Heck.. it's 96 degrees and one side says 102 and the shady side says it's 94.. but the spare says it's 89 degreesand107 psi...

Now what the heck do I do...��
Rotate them every 50 miles
__________________
2020 Cougar 315 RLS
2020 Ram 3500 6.7HO 4.10 Dually Aisin
jasin1 is offline   Reply With Quote
Old 09-30-2021, 05:02 PM   #42
Gunny Mike
Senior Member
 
Join Date: Apr 2019
Location: Peru
Posts: 128
VIAIR 46 000 Tire Inflation Gun, 160 Psi, 2.5" Mechanical Gauge, 1 Pack
Visit the VIAIR Store
4.7 out of 5 stars 26 ratings
Gunny Mike is offline   Reply With Quote
Old 09-30-2021, 05:09 PM   #43
flybouy
Site Team
 
Join Date: Oct 2011
Location: Joppa, MD
Posts: 11,082
Quote:
Originally Posted by Javi View Post
I got a TS something or 'other 507 something and I turn it on to see if my tires are somewhere between 105 psi and 115 psi... yep... I'm good

Heck.. it's 96 degrees and one side says 102 and the shady side says it's 94.. but the spare says it's 89 degrees and107 psi...

Now what the heck do I do...��
A ≤ + B≤ = ...oooops that's dat geometry I took in muddle skool. I guess add'rm snd divide by 3bto get the average?
__________________
Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
flybouy is offline   Reply With Quote
Old 09-30-2021, 05:42 PM   #44
wegone
Senior Member
 
Join Date: Jun 2020
Posts: 499
Since we are on the subject....
When you see the name sourdough participating in the discussion, now be honest here...
Do you think of hot buttered buns?
wegone is offline   Reply With Quote
Old 09-30-2021, 05:43 PM   #45
wegone
Senior Member
 
Join Date: Jun 2020
Posts: 499
Quote:
Originally Posted by Javi View Post
I got a TS something or 'other 507 something and I turn it on to see if my tires are somewhere between 105 psi and 115 psi... yep... I'm good

Heck.. it's 96 degrees and one side says 102 and the shady side says it's 94.. but the spare says it's 89 degrees and107 psi...

Now what the heck do I do...��
Didn't the Tinman answer this in the Wizard of Oz?
wegone is offline   Reply With Quote
Old 09-30-2021, 05:49 PM   #46
sourdough
Site Team
 
Join Date: Feb 2014
Location: W. Texas
Posts: 16,181
Quote:
Originally Posted by Island Eddie View Post
Since we are on the subject....
When you see the name sourdough participating in the discussion, now be honest here...
Do you think of hot buttered buns?

I think most folks I know think of the first 4 letters......
__________________
Danny and Susan, wife of 55 years
2019 Ram 3500 Laramie CC SB 6.4 4x4 4.10
2020 Montana High Country 331RL
sourdough is offline   Reply With Quote
Old 09-30-2021, 06:17 PM   #47
wegone
Senior Member
 
Join Date: Jun 2020
Posts: 499
Quote:
Originally Posted by sourdough View Post
I think most folks I know think of the first 4 letters......
Sweet has 5 letters

My wife bakes a lot....one of the most wonderful aromas is bread baking in the oven.

When it comes out of the oven all piping hot, you can barely hold it to slice, then lather on some cold butter...

OH MY.....

It's better than sex...er, I think, I don' remember
wegone is offline   Reply With Quote
Old 09-30-2021, 06:59 PM   #48
jasin1
Senior Member
 
jasin1's Avatar
 
Join Date: Aug 2020
Location: Upper Chesapeake Bay
Posts: 4,412
Quote:
Originally Posted by Tireman9 View Post
Not sure if I agree that an external TPMS is reporting the temp of the air inside the tire.

1. Air is a good insulator so why / how would that small column of air inside the stem override the temperature of the Brass stem that is conducting heat directly from the rim to the metal base of the sensor?

2. My test of running both an internal and external sensor shows the external sensors run 20F to 30F cooler than the internal sensors
3 Tire pressure with change by about 2% for each change in temperature of 10įF. I posted the mathematical proof on my blog.
Well I would think that the overall volume of air is constantly moving inside the tire..as the tire rotates it compresses along different points constantly as the tire hits the ground and momentarily changes shape..thousands of times over and over…a tire isn’t a steel tank that is holding air sitting on a shelf ( or would centrifugal force override that?)

So I think the air in the valve stem would have a fair representation of the air temp inside the tire ( close enough).and the heat of the wheel/rim would either be somewhat lost to the cooler air inside or to the atmosphere but don’t think one will have a relationship without the other being proportionally affected.
My point being as a laymen and not an engineeer is that the tpms sensor will have a fair sense of air temperature whether it’s an internal or external because the actual temp sensor is in direct contact with the air inside, whether it’s inside the wheel or 1.5 inches up the stem….

and yes I know I’m spending too much time on this issue lol


I have the tpms just for peace of mind to make sure all the tires are around the same temp and pressure ..nothing more
__________________
2020 Cougar 315 RLS
2020 Ram 3500 6.7HO 4.10 Dually Aisin
jasin1 is offline   Reply With Quote
Old 09-30-2021, 07:09 PM   #49
wiredgeorge
Senior Member
 
wiredgeorge's Avatar
 
Join Date: Nov 2017
Location: Mico, TX
Posts: 6,405
Quote:
Originally Posted by P&DZ View Post
Mikelff
You mentioned you use a high end accurate tire gauge. Can you please provide the details on that gauge. I have two dial tire gauges and neither read the same or correspond to the GMC TPMS.

Slime makes pretty accurate digital tire gauges; they have a low (up to 60 PSI) and a higher PSI gauge. They are less than $10 or so as I recall. I have several.
__________________
wiredgeorge Mico TX
2006 F350 CC 4WD 6.0L
2002 Keystone Cougar 278
2006 GL1800 Roadsmith Trike
wiredgeorge is offline   Reply With Quote
Old 09-30-2021, 07:28 PM   #50
sourdough
Site Team
 
Join Date: Feb 2014
Location: W. Texas
Posts: 16,181
Quote:
Originally Posted by jasin1 View Post
Well I would think that the overall volume of air is constantly moving inside the tire..as the tire rotates it compresses along different points constantly as the tire hits the ground and momentarily changes shape..thousands of times over and overÖa tire isnít a steel tank that is holding air sitting on a shelf
So I think the air in the valve stem would have a fair representation of the air temp inside the tire..and the heat of the wheel/rim would either be somewhat lost to the cooler air inside or to the atmosphere but donít think one will have a relationship without the other being proportionally affected. (or would centrifugal force override that?)
My point being as a laymen and not an engineeer is that the tpms sensor will have a fair sense of air temperature whether itís an internal or external because the actual temp sensor is in direct contact with the air inside, whether itís inside the wheel or 1.5 inches up the stemÖ.

and yes I know Iím spending too much time on this issue lol


I have the tpms just for peace of mind to make sure all the tires are around the same temp and pressure ..nothing more


And there you have it....
__________________
Danny and Susan, wife of 55 years
2019 Ram 3500 Laramie CC SB 6.4 4x4 4.10
2020 Montana High Country 331RL
sourdough is offline   Reply With Quote
Old 09-30-2021, 11:35 PM   #51
jadatis
Senior Member
 
Join Date: May 2013
Location: Holland ( Europe)
Posts: 165
Quote:
Originally Posted by jasin1 View Post
Huh??ÖÖthatís a lot of numbers
.
.refrigeration uses a pressure temp relationship because a particular gas has a specific pressure at a specific temperatureÖyou can figure out what kind of refrigerant is in a system based on that( as long as it isnít multiple types thrown in.

But I believe the tpms on the valve stems use an internal temp sensor that measures the inside wheel air temp itselfÖ.I have multiple different hvac instruments that do that ..or it converts it in its reading displayed

This is from my faq questions for my tpms monitor..it states the temp is from within the tire not external
In that document the question was misunderstood.
They assumed the questioner thougt the sensor gave temp of rubber of tire, but its the temp of air in tire. But they oversaw the real question, if it gave the temp of air inside tire.
And external sensors dont.
Even profesionals can make mistakes.

But temp in tire is not that important to know,but when people have tmps they want to know, because they can read it.

That is why I made the list to comfort their mind.
And the complete list from 20 psi to 179 psi.
You only need to search in that for your used pressures, and remember the degrF/psi forvyour pressures. Even grooped them to make the list shorter. And rounded to 0.5 degrF, because acurate enaugh for the purpose, and that purpose is that you can play with it on the road.

But also for cold filling of the pressure it can be used.
Some profesionals dont agree with my idea , but here it is.

Example , you determined needed pressure to be 80 psi.
From 78psi to 86psi the temp changes 5.5 degr/psi in the list.
Then if you fill or check at ambiŽnt temp of 95 degrF, so also tire inside , then 95-70= 25degr hotter, 25 /5.5= roughly 4, so 4 times 1psi higher pressure so 84 psi needed to fill or measure .
If you then use 80 psi, overheating of tire is possible in extremer situations.

When fi 40 degr ambiŽnt temperature is 30 degr colder then 70 degr, 30/5.5=5 to 6psi lower eaugh for safety of tire, so 74psi , but difference then is that you may use 80 psi for riding quality or fuesaving reasons.

This saves you a lot of changing pressure every trip.
jadatis is offline   Reply With Quote
Old 10-01-2021, 11:41 AM   #52
Tireman9
Senior Member
 
Join Date: Sep 2018
Location: Akron
Posts: 439
Quote:
Originally Posted by jadatis View Post
In that document the question was misunderstood.
They assumed the questioner thougt the sensor gave temp of rubber of tire, but its the temp of air in tire. But they oversaw the real question, if it gave the temp of air inside tire.
And external sensors dont.
Even profesionals can make mistakes.

But temp in tire is not that important to know,but when people have tmps they want to know, because they can read it.

That is why I made the list to comfort their mind.
And the complete list from 20 psi to 179 psi.
You only need to search in that for your used pressures, and remember the degrF/psi forvyour pressures. Even grooped them to make the list shorter. And rounded to 0.5 degrF, because acurate enaugh for the purpose, and that purpose is that you can play with it on the road.

But also for cold filling of the pressure it can be used.
Some profesionals dont agree with my idea , but here it is.

Example , you determined needed pressure to be 80 psi.
From 78psi to 86psi the temp changes 5.5 degr/psi in the list.
Then if you fill or check at ambiŽnt temp of 95 degrF, so also tire inside , then 95-70= 25degr hotter, 25 /5.5= roughly 4, so 4 times 1psi higher pressure so 84 psi needed to fill or measure .
If you then use 80 psi, overheating of tire is possible in extremer situations.

When fi 40 degr ambiŽnt temperature is 30 degr colder then 70 degr, 30/5.5=5 to 6psi lower eaugh for safety of tire, so 74psi , but difference then is that you may use 80 psi for riding quality or fuesaving reasons.

This saves you a lot of changing pressure every trip.



Sorry but you went off the deep end and probably confused everyone.


There is no adjustment or calculation needed when inflating your tires. Assuming you know the MINIMUM inflation needed to support the measured load on your tires, I and other actual tire engineers recommend you set the tires to no lower than that pressure when the tire is at Ambient temperature (That means not warmed from being in the sun or from being driven on in the previous 2 hours.)
I suggest you add 10% to that "minimum" inflation number so you don't have to adjust tire pressure every day because the Ambient temperature changed. Since pressure only changes about 2% for every change in Ambient of 10įF that means you would need something like a 50F change in ambient before you need to change your "set pressure".


I see no need for the table of temperature vs pressure as using a 2% for 10F figure is close enough.


Personally I would be just as happy if there was no temperature reading from TPMS as it concerns tires. The only value to a temperature reading is when there is a mechanical problem such as dragging brakes or bad bearings which will heat up the metal parts which will be reported as a temperature increase with most TPM Sensors.
__________________
Retired Tire Design Engineer (40 years). Serve on FMCA Tech Advisory Committee. Write a blog RV Tire Safety. Read THIS post on Why Tires Fail.
Tireman9 is offline   Reply With Quote
Old 10-01-2021, 12:34 PM   #53
travelin texans
Senior Member
 
travelin texans's Avatar
 
Join Date: Nov 2017
Location: Picacho, Az
Posts: 6,639
Adjusting tire pressures & torquing the lug nuts everyday every stop every temperature or elevation change is not happening in my world, it's not necessary for either unless there's a problem.
Tire pressures get checked probably monthly depending on the information provided by the TPMS. The lugs get checked at the 1st nightly stop after the wheels have been removed & not again til the wheels have been removed the next time. BTW, there is a proper procedure to follow when torquing the lug nuts & it's not just give them a couple clicks with the torque wrench everyday. Never had an issue with this procedure towing 10 years fulltiming or any of the 30+ years towing prior to that. YMMV!
Also it really didn't make a difference to me whether the TPMS was reading internal tire temps, I was interested in the tire temperature. If the TPMS is reading a 100 then the tire is most likely a 100 degrees to the touch which will make an increase to the internal temperature to 100+/-, so whatever the reading, temp or pressure, was close enough for me as long as all were close to the same on either side.
__________________
Full-timed 10+ years
Sold '13 Redwood FB
Traded '13 GMC Denali DRW D/A
Replacement undetermined
travelin texans is offline   Reply With Quote
Old 10-01-2021, 12:44 PM   #54
jadatis
Senior Member
 
Join Date: May 2013
Location: Holland ( Europe)
Posts: 165
Answer to post #52 above.

I wrote" But also for cold filling of the pressure it can be used.
Some profesionals dont agree with my idea , but here it is.

When I calculate pressure, I calc it for 10% more for reserve, to cover R/L unbalance, inacuracies in weigt and pressure determination, gives highest reserve with still acceptable comfort and gripp.
That little more lesser deflection by higher pressure at higher temperature then wont give discomfort. But my reserves are not meanth for those temperature changes.

Goal is to never overheat any part of tire.
Once overheated internal crackes are made, but it can take 3 years before they crack that much further, that tire blows, and then the real cource is long forgotten.
So this may only happen ZERO times in tires use.

But the ambiŽnt temperature change is solved automatically, higher pressure gives lesser deflection so heatproduction at same speed, cooling down is also lesser at that ambiŽnt temp.

So if you then lower the pressure to advice, balance between heating up and cooling down shifts to a higher temperature of rubber.

But again, tmps system brings new worries, and possible wrong reactions that can lead to tire failure. Then if you choose tmps, I give the things that can give wrong handling, so you are warned.

My list is one part of it, made several in the past, but to complicated. This one is yust as simple as tmps is worth.

Once set the right pressure, checking is OK, but dont mess with it.
I wonder if disturbing the valve every trip wont give valve-failure in time.
jadatis is offline   Reply With Quote
Old 10-01-2021, 03:04 PM   #55
NMRandy
Member
 
Join Date: Mar 2020
Location: Rio Rancho
Posts: 70
I run a GUTA TPMS that I bought cheap on Amazon. It works good. (well, the second one does! LOL). I set at 95 PSI at ambient temp. After about 15 min of driving I am over 100 PSI, and get as high as 110 PSI after an hour. Will this hurt the tire?
NMRandy is offline   Reply With Quote
Old 10-01-2021, 04:18 PM   #56
flybouy
Site Team
 
Join Date: Oct 2011
Location: Joppa, MD
Posts: 11,082
Quote:
Originally Posted by NMRandy View Post
I run a GUTA TPMS that I bought cheap on Amazon. It works good. (well, the second one does! LOL). I set at 95 PSI at ambient temp. After about 15 min of driving I am over 100 PSI, and get as high as 110 PSI after an hour. Will this hurt the tire?
Is 95 psi the correct cold inflation pressure? Are all the tires the same pressure? An increase in tire pressure after driving is normal, that's why it's a cold inflation number that you set the initial pressure to. As for the amount of indrease after driving there's several variables that effect that including road surface temps, road surface, ajount of breaking, turning, even direct sunlight vs shade.
__________________
Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
flybouy is offline   Reply With Quote
Old 10-01-2021, 11:57 PM   #57
jadatis
Senior Member
 
Join Date: May 2013
Location: Holland ( Europe)
Posts: 165
Quote:
Originally Posted by NMRandy View Post
I run a GUTA TPMS that I bought cheap on Amazon. It works good. (well, the second one does! LOL). I set at 95 PSI at ambient temp. After about 15 min of driving I am over 100 PSI, and get as high as 110 PSI after an hour. Will this hurt the tire?
Asuming the ambiŽnt temp when filled 95 psi, was 70 degrF, my list gives 5degrF/ psi.
100psi then 5x5degr higher is 95 degrF, wich is not bad.
110psi is 15psi higher so 15x5= 75degr+70=145 degr temp in tire.
And that is , if no external factors like fi high ambiŽnt temp, a bit to hot.

I determined 140 degr max at 70 degr F ambiŽnt temp, even at higher speed.

Can be because of high speed, high ambiŽnt temp, but most likely , as written already, that cold filled 95 psi is to low for the speed and load on tires.

If you give the needed data, I will calculate advice with maximum reserve with still acceptable comfort and gripp.

Tire data : maxload or loadindex, loadrange to determine reference-pressure and if ST, then also sises.

Of TT or whatever: best weighed axle( end) loads, but if not available, GAWR's and GVWR, and if Tt or 5thwh to determine expected % towbar(plate) .

To get back on the original question:

When driving 50-55 mph constant at ambiŽnt temp of 70 degrF , with pressure with comfortable reserve, temp of air in tire rises to about 110-115 degrF , wich would give for 95psi cold 8.5 psi rise, lets say 10% rising of pressure( speed most likely higher).
Max temp of inside tire air already given 140 degrF. Calc yourselfes the pressure rising it gives.

But external factors can rise the inside tire aire more, and dont need to be a problem for the tire always.

One example: when descending from the mountains and using the brakes to often, the heat of the brakes transported trough the rimm , can rise the air inside tire to boiling point of water ( at 14.7psi) is 212 degrF.

212-70= 142 degr hotter, would give /5 = 28psi rise +95 = 123psi pressure!!!!.

But then you better worry about the brake-oil boiling, the tires can have that pressure, and gives lesser deflection so lesser heatproduction a cycle, and because of low speed lesser cycles a second, so heatproduction a second lesser, so most likely the rubber of tire still dont come above a critical temp, at wich it hardens and crackes are made.

So then dont lower the pressure or overheating of tire will happen. Try to brake on the motor, so you dont use the brakes, and use a verry low speed fi 25mph. Anoying for those behind you.

This is one of the troubles you create with tmps, if you dont know the temps and pressures, you dont worry about it, but now you know not to worry.
jadatis is offline   Reply With Quote
Old 10-02-2021, 04:40 AM   #58
xrated
Senior Member
 
xrated's Avatar
 
Join Date: Oct 2016
Location: "Murvil, TN
Posts: 2,135
Good Grief........This thread went completely off the rails and into a seemingly bottomless pit. Maybe I missed something here, but I thought the discussion was about tire pressure monitors....maybe which ones were reliable and performed as they were designed to do....NOT the the physics of tire pressure/temperature relationships, heat calculations, and such. I am planning on getting rid of my Tireminder system sometime between now and next spring and was hoping for information about brands that provide reliability, longevity, and consistent performance. IS THERE ANY HOPE for that........vs. the college level physics discussion that is currently going on? Someone please just let me know so that I can either come back to this thread or just move on to something that is going to provide the info that was being discussed in the beginning!
__________________
2016 F350 King Ranch Crew Cab Dually Diesel 4x4
2018 Grand Design Momentum 394M
2019 Can Am Spyder RT Limited (Phoenix Orange)
Excessive payload capacity is a wonderful thing

"If it ain't Fast....It ain't Fun"
xrated is offline   Reply With Quote
Old 10-02-2021, 06:07 AM   #59
Javi
Senior Member
 
Join Date: Aug 2012
Location: Waco, Tx
Posts: 5,451
Quote:
Originally Posted by xrated View Post
Good Grief........This thread went completely off the rails and into a seemingly bottomless pit. Maybe I missed something here, but I thought the discussion was about tire pressure monitors....maybe which ones were reliable and performed as they were designed to do....NOT the the physics of tire pressure/temperature relationships, heat calculations, and such. I am planning on getting rid of my Tireminder system sometime between now and next spring and was hoping for information about brands that provide reliability, longevity, and consistent performance. IS THERE ANY HOPE for that........vs. the college level physics discussion that is currently going on? Someone please just let me know so that I can either come back to this thread or just move on to something that is going to provide the info that was being discussed in the beginning!
Go get a TST 507 and go camping 🏕
Javi is offline   Reply With Quote
Old 10-02-2021, 07:11 AM   #60
travelin texans
Senior Member
 
travelin texans's Avatar
 
Join Date: Nov 2017
Location: Picacho, Az
Posts: 6,639
Quote:
Originally Posted by Javi View Post
Go get a TST 507 and go camping 🏕
I'd highly recommend the same!
NO scientific slide rule required!
__________________
Full-timed 10+ years
Sold '13 Redwood FB
Traded '13 GMC Denali DRW D/A
Replacement undetermined
travelin texans is offline   Reply With Quote
Reply

Thread Tools
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
Forum Jump

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by the Keystone RV Company or any of its affiliates in any way. Keystone RVģ is a registered trademark of the Keystone RV Company.


All times are GMT -8. The time now is 07:24 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2023, vBulletin Solutions, Inc.