Reply
 
Thread Tools Search this Thread Display Modes
 
Old 04-04-2015, 04:01 PM   #1
2 Rivet Member
 
Sarasota , Florida
Join Date: Sep 2011
Posts: 72
Run TT tires with less than max pressure?

We have many campfire discussions on this subject. My 95 34' AS is getting new axles, 3500#. The trailer loaded for the road weighs 9700# on the CAT truck scales. I have E rated tires on it (6X2800#=16,800#) therefore the load carring capacity of the tires is more than the trailer weighs.

What are the consequences of lowering the tire pressure to less than 80psi in order to soften the ride?

The new axles haven't been installed yet, but surely will dampen the road. The original axles are shot, no movement what soever.

Four of the tires are less than 6 months old, other two are 2 years old.

Are there advantages/disadvantages to using D rated tires at 60psi?

Welcome your input.
__________________

__________________
DavidSowder is offline   Reply With Quote
Old 04-04-2015, 04:31 PM   #2
Rivet Master

 
1986 31' Sovereign
Miami , Florida
Join Date: Feb 2004
Posts: 1,650
Blog Entries: 13
I'll bet there is a load table somewhere on the manufacturer's website that would tell you the appropriate pressure for a given load. I would be very comfortable following those recommendations.

Mike


Sent from my iPad using Airstream Forums
__________________

__________________
Old (usually dirty) Nissan Titan
Old (enhanced with "male pattern baldness") Sovereign
Young, lovely bride
Goofy dog, dismissive cat
n2916s is offline   Reply With Quote
Old 04-04-2015, 05:10 PM   #3
Rivet Master
 
AnnArborBob's Avatar
 
2014 27' FB Eddie Bauer
Chelsea , Michigan
Join Date: May 2010
Posts: 1,763
Images: 12
We have the Michelin LT tires that AS ships on the newer higher-end trailers and the load tables indicate that we could inflate to 45 psi and still be safe. I inflate to 55 psi for a margin of safety. The benefit is a softer ride for the trailer which means fewer popped rivets and less wear and tear on the trailer and its cargo.

There are lots of threads on this subject in the forum. Some of the comments on those threads are by informed people and others are by less informed people. It's pretty easy to identify which type is making a particular comment.

I would use the "search" function and read up on this subject so you can feel confident in whatever decision you make.
__________________
Bob Martel
WBCCI# 5766
AnnArborBob is offline   Reply With Quote
Old 04-04-2015, 06:00 PM   #4
3 Rivet Member
 
1976 31' Sovereign
Springfield , South Carolina
Join Date: Jul 2010
Posts: 233
I just posted my experience with TTs, 80 PSI and heavier axles thought you might like to see along with evidence of how smooth it rides.

http://www.airforums.com/forums/f437...ke-133219.html

http://www.airforums.com/forums/f439...-133041-2.html
__________________
Hummer is offline   Reply With Quote
Old 04-04-2015, 06:33 PM   #5
4 Rivet Member
 
carver 1's Avatar
 
2011 30' Classic
2007 25' International CCD
1993 32' Excella
Largo , Florida
Join Date: Nov 2013
Posts: 355
Images: 30
David,

We've been running with 80 PSI with our 16" Michelin LTs and had similar experience as concerns leaving objects out on counter tops and were amazed to fnd that they did not move on a recent trip to Sebring. I do not know the rating of the original axles that my 2011 Classic 30 comes with. I can't help but feel that part of this is due to the adjustment of the WD bars on my Pro Pride. I would really be interested to find out what advice Switz would have on this subject.

>>ron<<
__________________
2015 GMC Denali 2500, 4x4, Duramax diesel, Topper, Pro Pride 3 P, Sendel 16" with Michelin LTs, one Yellow Labrador Retriever (AS security)
carver 1 is offline   Reply With Quote
Old 04-04-2015, 07:19 PM   #6
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 7,584
Images: 1
The per tire load on a tridem is quite different than for a tandem. E-rated really was overkill, assuming weight readings per wheel do not show large discrepancies.

A commercial LT tire such as the Yokohama RY-215 or Andrew Thomsons specific Michelin LTX recommendation would be better.

The load index would be more appropriate.

Full sidewall pressure is always best. The Load & Pressure Tables are not applicable to trailer use.
__________________
1990 35' Silver Streak Sterling; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 9-cpm solo, 15-cpm towing
Sold: Silver Streak Model 3411
slowmover is offline   Reply With Quote
Old 04-04-2015, 09:12 PM   #7
Rivet Master
 
Larry C's Avatar
 
1996 34' Excella
Elberta , Alabama
Join Date: Oct 2006
Posts: 745
Finally, someone who knows that to realize the capacity of a given load range tire, one has to inflate to the maximum pressure!
That being said, on our 30' Excella, with the original Goodyear Marathons, inflated to the magic 60 PSI, we have always managed to blow out tires, in fact, rather consistantly.

Since then with LR "E" Carlyles, inflated to 80 PSI, there have been no problems. I have an AirSafe system, which gives the AS a "soft" ride, and no problems with popped rivets, etc.

I just finished a 1996 34' remodel, also installed LR "E", on it, and will do the same thing. It's easy to "overthink" things. If it ain't broke, don't fix it.

Larry


Quote:
Originally Posted by slowmover View Post
The per tire load on a tridem is quite different than for a tandem. E-rated really was overkill, assuming weight readings per wheel do not show large discrepancies.

A commercial LT tire such as the Yokohama RY-215 or Andrew Thomsons specific Michelin LTX recommendation would be better.

The load index would be more appropriate.

Full sidewall pressure is always best. The Load & Pressure Tables are not applicable to trailer use.
__________________
Old age is coming at a really bad time!

1996 34' Excella 1000, interior totally redone, 2003 Dodge/Cummins HO, U.S. Gear exhaust brake, Diablo tuner, 115 gallon aux fuel, Bedslide, Airsafe/Reese Dual Cam, and a bunch of other stuff
Larry C is offline   Reply With Quote
Old 04-04-2015, 09:20 PM   #8
Rivet Master
 
SteveSueMac's Avatar

 
2012 27' Flying Cloud
W , New England
Join Date: Oct 2012
Posts: 5,409
Larry - aren't those D load Marathons supposed to be at 65 (not 60) PSI? Those 5 lbs under could be connected with multiple failures, I think...

65 PSI to get the 2540 per tire and 65 MPH max speed limit (I know yo can go to 75 MPH with 10 more PSI but load does not increase...).
__________________
SteveSueMac is offline   Reply With Quote
Old 04-04-2015, 10:32 PM   #9
3 Rivet Member
 
1976 31' Sovereign
Springfield , South Carolina
Join Date: Jul 2010
Posts: 233
Are you guys checking tire temps with infra thermometers. If they run hot they will blow.

If I remember correctly you don't want your tires getting over 135F. As I remember in summer tire temps get to about 122 check temps on all tires, if one is getter significantly hotter than the rest you better check air pressure.
__________________
Hummer is offline   Reply With Quote
Old 04-04-2015, 10:43 PM   #10
1987 Avion 34W owner
 
PaulnGina's Avatar
 
Vintage Kin Owner
Good Ol' , USA
Join Date: Mar 2014
Posts: 1,889
I recently had 6 Commodore 225/75R15's on our 1987 Avion 34W. They achieve 2540 lbs per tire at 50 psi.

I look forward to seeing how these tires perform on the Avion.
__________________
"Long lay the world in sin and error pining
Till He appeared and the soul felt its worth"
1987 Avion 34W
1995 Ford F250 7.3L PowerStroke
PaulnGina is offline   Reply With Quote
Old 04-05-2015, 06:24 AM   #11
Rivet Master
 
Currently Looking...
Nowhere , Somewhere
Join Date: Jul 2005
Posts: 6,421
Blog Entries: 2
When in doubt, max the pressure out! Peace,jim
__________________
avionstream is offline   Reply With Quote
Old 04-05-2015, 08:58 AM   #12
retired USA/USAF

 
2001 30' Excella
Somerset , New Jersey
Join Date: Jan 2009
Posts: 2,156
I run Michelin 16" LT's on our 30' AS. Last summer I thought I would lower the tire pressure a bit in hopes of softening the ride. I dropped the pressure from the max 80 to 55 ( I think). For the first time ever I found severe sway at highway speed. Back up to 80 and as expected, no more sway. So 80 it is for me. I do still find a drawer or two opening and a few things shift around but not as bad as when I had the GYM LT's on it. Ironically we do leave some things on the kitchen counter and they usually stay put unless we are on some really rough roads.

See ya'll on the road sometime.
__________________
Roger in NJ

" Democracy is the worst form of government. Except for all the rest"
Winston Churchill 1948

TAC - NJ 18

polarlyse is offline   Reply With Quote
Old 04-05-2015, 09:51 AM   #13
Rivet Master
 
Larry C's Avatar
 
1996 34' Excella
Elberta , Alabama
Join Date: Oct 2006
Posts: 745
My bad call re the 60 PSI, I found one of my old check lists, and they were inflated to 65 PSI. The real cause of the failures of the GYM's was poor quality tires. I've heard that they have finally solved the problem, I have no idea of what those problems were, but I'll simply not buy them anymore.
I've had excellent performance from the Carlyle "E" rated, so I'll stay with them....

Thanks for calling me on this mistake.

Larry



Quote:
Originally Posted by SteveSueMac View Post
Larry - aren't those D load Marathons supposed to be at 65 (not 60) PSI? Those 5 lbs under could be connected with multiple failures, I think...

65 PSI to get the 2540 per tire and 65 MPH max speed limit (I know yo can go to 75 MPH with 10 more PSI but load does not increase...).
__________________
Old age is coming at a really bad time!

1996 34' Excella 1000, interior totally redone, 2003 Dodge/Cummins HO, U.S. Gear exhaust brake, Diablo tuner, 115 gallon aux fuel, Bedslide, Airsafe/Reese Dual Cam, and a bunch of other stuff
Larry C is offline   Reply With Quote
Old 04-05-2015, 11:23 AM   #14
Rivet Master
Commercial Member
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 690
There is sound factual engineering evidence to support the need to

1. Get on a scale and using the appropriate worksheet learn the actual load on each tire with the RV at full load, to ensure no tire is in overload. I have read where more than 25% of RVs have more than 400# side to side un-balance. There are probably a similar percent with unbalance axle to axle.

2. Inflating trailer tires to the pressure on the tire sidewall is the best practice available to trailer owners to lower the "Interply Shear" forces on the tire belts. This force can be more than 20% higher in trailers than motorhomes or pickups when turning any corner or radius. It is this force along with the rubber being degraded from the heat from excess speed, low inflation and excess load that exceeds the properties of the belt rubber. This can result in the belt separations seen on many tires in trailer application.

If you want to understand why this "Interply Shear" force is important you can Google the term to read more. You can lower, but not eliminate, it with increased inflation.
__________________

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


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
3rd battery for less than 10 bucks john hd Batteries, Univolts, Converters & Inverters 18 09-17-2007 08:34 PM
Why is GVWR less than GAWRs? acbillard Tow Vehicles 6 05-19-2007 08:24 PM
Want A New Interior For Less Than $5.00? Inland RV Center, In Upholstery, Blinds, Walls & Interior Finishes 2 05-03-2002 11:35 AM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 12:46 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.