Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-07-2018, 07:33 PM   #1
3 Rivet Member
 
2018 19' Flying Cloud
Eugene , Oregon
Join Date: Mar 2015
Posts: 129
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
__________________

tjwoods1 is offline   Reply With Quote
Old 11-07-2018, 09:22 PM   #2
Rivet Master
 
ITSNO60's Avatar
 
Currently Looking...
Tucson , AZ
Join Date: May 2017
Posts: 816
Quote:
Originally Posted by tjwoods1 View Post
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
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
ITSNO60 is offline   Reply With Quote
Old 11-08-2018, 06:53 AM   #3
.-. -...
 
Adventure.AS's Avatar

 
2017 25' International
Port Dover , ON Canada
Join Date: May 2016
Posts: 1,203
Quote:
Originally Posted by ITSNO60 View Post
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.
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.

“One test is worth a thousand 'expert' opinions”
Sign at Boeing headquarters, posted by test pilot Alvin “Tex” Johnston, c1948
Adventure.AS is online now   Reply With Quote
Old 11-08-2018, 07:18 AM   #4
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 877
Quote:
Originally Posted by tjwoods1 View Post
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

Already answered HERE.
__________________
Retired tire engineer (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 11-08-2018, 07:51 AM   #5
Rivet Master
 
2014 20' Flying Cloud
Long Island , New York
Join Date: Jun 2015
Posts: 8,860
Parallel threads, which Tireman has already linked:

http://www.airforums.com/forums/f542...-a-189156.html
OTRA15 is offline   Reply With Quote
Old 11-08-2018, 09:34 AM   #6
Rivet Master
 
Mollysdad's Avatar
 
2017 26' Flying Cloud
Tampa , Florida
Join Date: Feb 2017
Posts: 2,792
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.
Mollysdad is offline   Reply With Quote
Old 11-08-2018, 11:36 AM   #7
Moderator dude
 
Action's Avatar

 
1966 26' Overlander
Phoenix , Arizona
Join Date: Apr 2002
Posts: 6,367
Images: 13
Quote:
Originally Posted by tjwoods1 View Post
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
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!
Action is offline   Reply With Quote
Old 11-08-2018, 04:10 PM   #8
3 Rivet Member
 
2018 19' Flying Cloud
Eugene , Oregon
Join Date: Mar 2015
Posts: 129
So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?
tjwoods1 is offline   Reply With Quote
Old 11-08-2018, 04:23 PM   #9
Rivet Master
 
Caffeinated's Avatar
 
2015 27' Flying Cloud
Portland , Oregon
Join Date: May 2015
Posts: 819
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
Caffeinated is offline   Reply With Quote
Old 11-08-2018, 04:29 PM   #10
Moderator dude
 
Action's Avatar

 
1966 26' Overlander
Phoenix , Arizona
Join Date: Apr 2002
Posts: 6,367
Images: 13
Quote:
Originally Posted by tjwoods1 View Post
So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?
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!
Action is offline   Reply With Quote
Old 11-08-2018, 04:42 PM   #11
3 Rivet Member
 
Wrangler's Avatar
 
2019 19' Flying Cloud
Renville , Minnesota
Join Date: Jul 2015
Posts: 104
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.
Wrangler is offline   Reply With Quote
Old 11-09-2018, 11:03 AM   #12
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 877
Quote:
Originally Posted by Mollysdad View Post
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.

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 (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 11-09-2018, 11:07 AM   #13
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 877
Quote:
Originally Posted by tjwoods1 View Post
So I would weigh the trailer - add 15% to that - and then look at the tire manufacturer chart for that inflation recommendation?

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 (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Old 11-09-2018, 11:09 AM   #14
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 877
Quote:
Originally Posted by Wrangler View Post
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.

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 (40 years). Write a blog on RV tires.
Tireman9 is offline   Reply With Quote
Reply

« What tires to buy? | Top | - »

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
Proper PSI for 19’ tjwoods1 2016 - Current Flying Cloud 7 11-08-2018 07:50 AM
100 PSI or 70 PSI? '92 300LE fangthorpe Airstream Motorhome Forums 5 09-16-2010 11:11 AM
Manual says ST225/75R15LRC 50 psi -- PO used ST225/75R15LRD at 65 psi Driver1 Tires 3 06-23-2008 09:26 PM
Tire PSI? ldetsf Tires 9 11-10-2006 09:18 AM
Shurflo regulator_50 psi is not 40 femuse Water Heaters, Filters & Pumps 6 03-28-2003 10:54 AM


Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:57 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.