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11-07-2018, 06:33 PM
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#1
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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Proper PSI
I asked this question in the Flying Cloud section, but perhaps it’s best asked here.
I have a 2018 Flying Cloud 19’ with 15” ST225/75R15 Goodyear Endurance tires. The maximum recommended inflation given in the Airstream manual is 80 psi. The Load / Inflation chart given by Goodyear for the tire is indeed 80psi but if I am reading the chart right, that is with 2830 lbs per tire (2830 x 2 = 5660). If so, the max GVWR for the 19’ is 4500 and again, if I am reading Goodyear’s chart correctly, would 55 psi for 2270 (2270 x 2 =4540) be a more correct psi for my trailer?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
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11-07-2018, 08:22 PM
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#2
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diesel maniac
Airstream - Other
Tucson
, AZ
Join Date: May 2017
Posts: 2,531
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Quote:
Originally Posted by tjwoods1
I asked this question in the Flying Cloud section, but perhaps it’s best asked here.
I have a 2018 Flying Cloud 19’ with 15” ST225/75R15 Goodyear Endurance tires. The maximum recommended inflation given in the Airstream manual is 80 psi. The Load / Inflation chart given by Goodyear for the tire is indeed 80psi but if I am reading the chart right, that is with 2830 lbs per tire (2830 x 2 = 5660). If so, the max GVWR for the 19’ is 4500 and again, if I am reading Goodyear’s chart correctly, would 55 psi for 2270 (2270 x 2 =4540) be a more correct psi for my trailer?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
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You're going to get two opinions on that. Many run the pressures on the load and inflation charts plus about 10% to allow for uneven loading, however resident tire expert Tireman9 (Roger Marble) is now recommending that trailer tires be inflated to their maximum sidewall markings. Lower pressure will give the trailer a softer ride but due to the shear placed on trailer tires Roger is now recommending full pressure. He does however still recommend using the tables for the tow vehicle tires.
__________________
Brian
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11-08-2018, 05:53 AM
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#3
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.-. -...
2017 25' International
Niagara-on-the-Lake
, ON Canada
Join Date: May 2016
Posts: 1,836
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Quote:
Originally Posted by ITSNO60
You're going to get two opinions on that. Many run the pressures on the load and inflation charts plus about 10% to allow for uneven loading, however resident tire expert Tireman9 (Roger Marble) is now recommending that trailer tires be inflated to their maximum sidewall markings. Lower pressure will give the trailer a softer ride but due to the shear placed on trailer tires Roger is now recommending full pressure. He does however still recommend using the tables for the tow vehicle tires.
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A 19', single axle Bambi doesn't experience the same 'tire shear' that a multi-axle trailer does, so IMO maximum PSI is definitely not required.
__________________
Ray B.
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11-08-2018, 06:18 AM
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#4
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Rivet Master
Commercial Member
Ravenna
, Ohio
Join Date: Apr 2012
Posts: 1,344
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Quote:
Originally Posted by tjwoods1
I asked this question in the Flying Cloud section, but perhaps it’s best asked here.
I have a 2018 Flying Cloud 19’ with 15” ST225/75R15 Goodyear Endurance tires. The maximum recommended inflation given in the Airstream manual is 80 psi. The Load / Inflation chart given by Goodyear for the tire is indeed 80psi but if I am reading the chart right, that is with 2830 lbs per tire (2830 x 2 = 5660). If so, the max GVWR for the 19’ is 4500 and again, if I am reading Goodyear’s chart correctly, would 55 psi for 2270 (2270 x 2 =4540) be a more correct psi for my trailer?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
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Already answered HERE.
__________________
Retired tire engineer (50 years). Write a blog on RV Tire Safety Net. Give seminars for FMCA across the US. Tucson AZ in Mar 2024 is next.
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11-08-2018, 06:51 AM
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#5
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Rivet Master
2014 20' Flying Cloud
Sag Harbor
, New York
Join Date: Jun 2015
Posts: 17,523
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11-08-2018, 08:34 AM
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#6
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Rivet Master
2017 26' Flying Cloud
Tampa
, Florida
Join Date: Feb 2017
Posts: 7,638
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I don't know how I made it through life without ever hearing "interply shear", and now I hear it every day. I love a good term.
You'll drive yourself nuts trying to understand and use inflation charts.
I settled on 65 psi, and watching the TPMS, I did not experience much heat buildup while on the road.
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11-08-2018, 10:36 AM
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#7
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Moderator dude
1966 26' Overlander
Phoenix
, Arizona
Join Date: Apr 2002
Posts: 7,501
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Quote:
Originally Posted by tjwoods1
I asked this question in the Flying Cloud section, but perhaps it’s best asked here.
I have a 2018 Flying Cloud 19’ with 15” ST225/75R15 Goodyear Endurance tires. The maximum recommended inflation given in the Airstream manual is 80 psi. The Load / Inflation chart given by Goodyear for the tire is indeed 80psi but if I am reading the chart right, that is with 2830 lbs per tire (2830 x 2 = 5660). If so, the max GVWR for the 19’ is 4500 and again, if I am reading Goodyear’s chart correctly, would 55 psi for 2270 (2270 x 2 =4540) be a more correct psi for my trailer?
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf
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You have posted a bunch of data that is mostly available on the internet. The one piece that you didn't post is the actual load. (The weight by wheel) Sure the trailer could handle the max GVWR. The question would be is this your actual load? Or is it possible you would load your trailer to the max GVWR?
Once known, you don't want to inflate the tire to meet the greatest load you expect, you want to inflate to exceed that load. By at least 10 to 15 percent. Riding in the edge is an OK thing in some arenas. Just not in the tire capacity arena. If the tires have the ability to handle 10 or 15 percent more, the tire has a better chance of surviving at the place where the rubber meets the road.
>>>>>>>>>>>>>Action
__________________
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!
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11-08-2018, 03:10 PM
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#8
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?
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11-08-2018, 03:23 PM
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#9
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Rivet Master
2015 27' Flying Cloud
Newberg
, Oregon
Join Date: May 2015
Posts: 1,052
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I’m no tire engineer, but I run my GYEs at 75 on my 27 ft FC. they have been running cool and the trailer pulls smoothly.
Mike
__________________
2015 27ft FC FB
WBCCI #3960
2019 F150 ecoboost
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11-08-2018, 03:29 PM
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#10
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Moderator dude
1966 26' Overlander
Phoenix
, Arizona
Join Date: Apr 2002
Posts: 7,501
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Quote:
Originally Posted by tjwoods1
So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?
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Yes -
If you use a P rated tire (versus a ST tire) you will have to degrade the capacity of the tire by 10%.
And you would want to use the heaviest wheel position for the weight as most travel trailers are un-equally loaded.
>>>>>>>>>>Action
__________________
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!
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11-08-2018, 03:42 PM
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#11
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Rivet Master
2019 19' Flying Cloud
Renville
, Minnesota
Join Date: Jul 2015
Posts: 510
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When I got my FC 19’, the label for tire pressure from Airstream says that the recommended pressure is 80 psi, which corresponds to the max tire pressure labeled on the tire. In My 50 plus years as a tire consumer, I have never seen this. Most often, the recommended pressure is in the vicinity of 30% under the max listed on the tire. Mechanics tend to fill tires to the max rating on the sidewall. That pressure usually results in over inflation and excess wear at the center tread. Given the data listed on Goodyear’s inflation/load chart. Why would I not experience over inflation wear if I use Airstream’s 80 psi inflation recommendation.
__________________
I currently camp in a 19’ Flying Cloud towed by a Nissan Frontier.
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11-09-2018, 10:03 AM
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#12
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Rivet Master
Commercial Member
Ravenna
, Ohio
Join Date: Apr 2012
Posts: 1,344
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Quote:
Originally Posted by Mollysdad
I don't know how I made it through life without ever hearing "interply shear", and now I hear it every day. I love a good term.
You'll drive yourself nuts trying to understand and use inflation charts.
I settled on 65 psi, and watching the TPMS, I did not experience much heat buildup while on the road.
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Interply Shear has always been there in radial tires but wasn't anything the operator could do about it till I put the technical term together with a chance observation of a large 5th wheel making a 180° turn in freshly smoothed gravel
PLUS had access to the two different computer programs that helped me understand why the tire path on the trailer was different than the path from non-towed vehicles.
__________________
Retired tire engineer (50 years). Write a blog on RV Tire Safety Net. Give seminars for FMCA across the US. Tucson AZ in Mar 2024 is next.
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11-09-2018, 10:07 AM
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#13
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Rivet Master
Commercial Member
Ravenna
, Ohio
Join Date: Apr 2012
Posts: 1,344
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Quote:
Originally Posted by tjwoods1
So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?
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That is the recommendation for motorhomes. My recommendation as a tire engineer for trailers is to inflate to the inflation shown on the tire sidewall (which is also probably the number on your certification lable) and run that inflation. To get better tire life you ALSO need to confirm your actual load is no more than 85% of the load capacity of the tire bases on the inflation you use.
I do cover this in detail in my RV tire blog.
Sorry but I can not post a hot link here.
__________________
Retired tire engineer (50 years). Write a blog on RV Tire Safety Net. Give seminars for FMCA across the US. Tucson AZ in Mar 2024 is next.
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11-09-2018, 10:09 AM
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#14
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Rivet Master
Commercial Member
Ravenna
, Ohio
Join Date: Apr 2012
Posts: 1,344
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Quote:
Originally Posted by Wrangler
When I got my FC 19’, the label for tire pressure from Airstream says that the recommended pressure is 80 psi, which corresponds to the max tire pressure labeled on the tire. In My 50 plus years as a tire consumer, I have never seen this. Most often, the recommended pressure is in the vicinity of 30% under the max listed on the tire. Mechanics tend to fill tires to the max rating on the sidewall. That pressure usually results in over inflation and excess wear at the center tread. Given the data listed on Goodyear’s inflation/load chart. Why would I not experience over inflation wear if I use Airstream’s 80 psi inflation recommendation.
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The center wear was more likely with bias tires. Radial treads do not respond to the same level as bias to inflation.
__________________
Retired tire engineer (50 years). Write a blog on RV Tire Safety Net. Give seminars for FMCA across the US. Tucson AZ in Mar 2024 is next.
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11-09-2018, 10:10 AM
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#15
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Rivet Master
Commercial Member
Ravenna
, Ohio
Join Date: Apr 2012
Posts: 1,344
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Quote:
Originally Posted by Caffeinated
I’m no tire engineer, but I run my GYEs at 75 on my 27 ft FC. they have been running cool and the trailer pulls smoothly.
Mike
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And the actual load is what percentage of the tire capacity ar 75 psi?
__________________
Retired tire engineer (50 years). Write a blog on RV Tire Safety Net. Give seminars for FMCA across the US. Tucson AZ in Mar 2024 is next.
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11-09-2018, 10:33 AM
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#16
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Rivet Master
2012 27' Flying Cloud
W
, New England
Join Date: Oct 2012
Posts: 7,402
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Quote:
Originally Posted by Tireman9
And the actual load is what percentage of the tire capacity ar 75 psi?
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I’m not caffeinated but I want to play along as I’m considering the GYEs for spring. On the scales loaded for camping and WD applied, my axles combined see 6000#. Running the GYEs at 65 PSI would provide 2540#/tire or 10,160# total load carrying capacity so the actual load would be 59% of the tires’ capacity at 65 PSI. Am I seeing that correctly??
If so, is there any reason not to run at 65 PSI instead of 80?
Thanks!
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11-09-2018, 10:50 AM
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#17
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Rivet Master
2017 28' International
Jim Falls
, Wisconsin
Join Date: Jul 2017
Posts: 2,300
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The recommended tire pressure for my tires is 80psi cold. Once on the road traveling that PSI is going to go up by about 10 to 15%. I think messing around with the tire pressure based upon load is getting just a bit ridiculous and you are asking for trouble. Fill it to the recommended PSI cold and leave it. That means in cooler weather putting more air in and in the summer putting less air in.
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11-09-2018, 11:40 AM
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#18
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Moderator dude
1966 26' Overlander
Phoenix
, Arizona
Join Date: Apr 2002
Posts: 7,501
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Quote:
Originally Posted by SteveSueMac
I’m not caffeinated but I want to play along as I’m considering the GYEs for spring. On the scales loaded for camping and WD applied, my axles combined see 6000#. Running the GYEs at 65 PSI would provide 2540#/tire or 10,160# total load carrying capacity so the actual load would be 59% of the tires’ capacity at 65 PSI. Am I seeing that correctly??
If so, is there any reason not to run at 65 PSI instead of 80?
Thanks!
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There may be a flaw. The above assumes all tires are loaded equally. For a TV usually the loading from side to side is pretty close to being equal. The front back or axle load usually differs measurably.
On a travel trailer the loading may be very unequal from side to side and front to back. If all of the tires average 59% there could be one that is 70%. It is an unknown. Sizing tire capacity to the tire position that has the greatest load would be desired.
>>>>>>>>>>>>>>>>Action
__________________
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!
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11-09-2018, 01:12 PM
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#19
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Rivet Master
1988 25' Excella
1987 32' Excella
Knoxville
, Tennessee
Join Date: Oct 2010
Posts: 5,103
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So how does it pull at 80 psi? Does it bounce around a lot? That much pressure would bother me. There is no addtional shear on a 1 axle trailer. So the picture of the 5 th wheel dragging is irrelevant.
I have not idea that there is even a "proper" inflation by definition in this case. I also would try 65 and then go down or up depending upon the results I got.
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11-09-2018, 01:26 PM
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#20
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Rivet Master
2015 27' Flying Cloud
Newberg
, Oregon
Join Date: May 2015
Posts: 1,052
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Quote:
Originally Posted by Tireman9
And the actual load is what percentage of the tire capacity ar 75 psi?
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I’ll have to find out next spring. 🤔
Mike
__________________
2015 27ft FC FB
WBCCI #3960
2019 F150 ecoboost
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