Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-19-2016, 05:02 PM   #29
3 Rivet Member
 
Adiredneck's Avatar
 
2014 27' FB Classic
Vicksburg , Mississippi
Join Date: May 2014
Posts: 172
Thanks, Tireman9.

I did understand the concept, and should not have called the steel sidewall a "belt". As Michelin describes it, it has a "steel casing" and three steel belts.

https://www.michelinb2b.com/wps/b2bc...Rib_DataPg.pdf

I did not see any mention of a steel casing on their other (less expensive) LT tires that most people on the Forum have chosen. Does it actually give any more protection against Interply Shear? How would you rate this tire for trailer use? (If you choose to answer - I don't mean to put you in a position to "endorse" a particular brand or model). Just curious if the extra $$$ bought any additional margins of safety over either the original 15" GYM or cheaper Michelin LT tires...

Tim
__________________

__________________
"Hot meals, cold beer, dry bed & flush toilet - everything I look for in a wilderness experience..."
Adiredneck is offline   Reply With Quote
Old 10-20-2016, 04:18 AM   #30
Rivet Master
 
2013 31' Classic
billings , Montana
Join Date: Feb 2010
Posts: 1,267
My ford had the same size tires as the neighbors motorhome, we bought tires about the same time at Costco, his were about $45 more. I looked at his tires they did have 1 steel cord in sidewall my pickup tire was polyester cord..
__________________

__________________
tjdonahoe is online now   Reply With Quote
Old 10-20-2016, 10:34 AM   #31
Rivet Master
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 589
Quote:
Originally Posted by Adiredneck View Post
Thanks, Tireman9.

I did understand the concept, and should not have called the steel sidewall a "belt". As Michelin describes it, it has a "steel casing" and three steel belts.

https://www.michelinb2b.com/wps/b2bc...Rib_DataPg.pdf

I did not see any mention of a steel casing on their other (less expensive) LT tires that most people on the Forum have chosen. Does it actually give any more protection against Interply Shear? How would you rate this tire for trailer use? (If you choose to answer - I don't mean to put you in a position to "endorse" a particular brand or model). Just curious if the extra $$$ bought any additional margins of safety over either the original 15" GYM or cheaper Michelin LT tires...

Tim
Interply Shear is observed at the edges of the belts. All radials have this force but the question is Can the owner do things to lower the level of shear force that is trying to separate the belts and separate the belts from the body and the tread components.

"Slip Angle" is the angel difference between the imaginary line of the direction of travel and the imaginary line of the direction of rotation of a tire. It normally is small, in the 1 to 2 range. However many trailers are forced into a 10 or higher angle when backing. Also the slip angle even in normal turning will be higher on trailers than on the tires on the tow vehicle because the center of rotation of the trailer tires is not at the center of the turn radius.

I have a post on my blog on Wednesday, May 25, 2016 with a diagram explaining this. Sorry AS forum doesn't allow me to post hot links to my blog in forum posts. You can visit my "Homepage" by clicking on my name.

Now with all this Techno Babble we need to get to the bottom line. You can lower the shear forces with lower slip angle. Lower the slip angle with higher inflation so that is why towables should run the tire sidewall inflation and not the inflation based on measured tire load as motorhomes do.

Hope this helps.
__________________
Tireman9 is offline   Reply With Quote
Old 10-22-2016, 08:21 PM   #32
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 6,510
Images: 1
Tire pressure on the road

Adiredneck, the "gold standard" is a complete set of numbers as to tire loads. Thus, the three pass method for using a scale (CAT Scale; most truck stops. Start by filling fuel tank).

First pass is full fuel plus driver and passengers + gear as loaded for trip (or simulated). Full fresh water and propane. WD tensioned as usual.

Second pass is same, but WD hitch without any tension applied.

Third pass is to drop trailer and get solo value of TV.

Since we're talking about tires, I'd make extra passes with Port then Starboard tires off of scale (TV only).

If you want to go all the way, then all tires on the combined rig for each "condition ". Looking for side to side discrepancies. Heaviest tire load on an axle determines air pressure value.

Seeing trailer tires load change from full WD tension to how well WD is being applied from no tension. Same with TV.

Today's hitch receivers don't distribute TW as well as the custom ones we had to have made in the 1960s and 1970s from factory diagrams. It's probably part of the reason for revision of how to use WD the past couple of years by OEMs.

These are the numbers one works from to make present WD adjustments (if needed) and as a check against future scale tickets (once yearly for a vacationer; pretty much a single pass. Unless you've been adding gear, etc).

They're also the way to have a handle on "best" TV tire pressure. IOW, what the lowest pressure one can run (after testing for pressure rise from cold). We know the upper limit. Now we want to know the full range. The validated range.

As with the hitch settings, we're looking for the range of either hitch adjustments or tire pressure that we can use.

Weird problems can crop up going down the highway. Is it a tire belt? Is it a driveshaft? Is it this different brand of tires? TT tire failure? Road surface irregularity? All kinds of crap to sort thru when something doesn't feel or act the right way.

And the only method to find "what is right" is to have a numerical baseline from the get go. Confirm that is correct, and the decision tree to finding problems with driving dynamics is much easier.


1990 35' Silver Streak
2004 555 Cummins
__________________
1990 35' Silver Streak Sterling; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 10-cpm solo, 18-cpm towing
Sold: Silver Streak Model 3411
slowmover is offline   Reply With Quote
Old 10-24-2016, 08:58 PM   #33
2 Rivet Member
 
Barbieri's Avatar
 
2004 30' Classic
San Antonio , Texas
Join Date: Oct 2016
Posts: 79
Quote:
Originally Posted by Tireman9 View Post
X2

Those suggesting to leave the tire pressure low are effectively telling you to run the tires overloaded and/or with higher Interply Shear forces that can lead to tread/belt separation tire failures.

Towables should alway set the "cold" ambient tire pressure to the tire sidewall to keep Interply Shear as low as possible no matter the type or size tires you run.

I would leave the tp alone. After driving a while the tp will be over 70. The ambient air temp determines the tire pressure. If you do that would be spending all day adjusting you tire pressure. By the way what is the ambient air temp?
__________________
Barbieri is offline   Reply With Quote
Old 10-25-2016, 02:34 PM   #34
Rivet Master
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 589
Quote:
Originally Posted by Barbieri View Post
I would leave the tp alone. After driving a while the tp will be over 70. The ambient air temp determines the tire pressure. If you do that would be spending all day adjusting you tire pressure. By the way what is the ambient air temp?
1. Assuming your tires are ST type Load Range E they most likely show 80 psi molded on the tire sidewall. To get the lower Interply Shear I suggest you use 80 psi as your "Cold Inflation Pressure"

2. CIP is the pressure when tires are not warmed by either driving or in sunshine for at least 2 hours.

3. "Ambient" air temperature is nominally the air temperature in the shade

4. Yes tire pressure will increase when you drive on the tire. The normal change is about 2% for each change of 10F. I have covered this in detail with the math formula in my blog. Tires are designed for this pressure change. It could even be argued that tires are depending on this pressure increase do deliver longer term durability as ALL tire development testing and ALL regulatory testing is done with air and the inflation pressure on the drum tests is allowed to increase accordingly.

5. You do not need to adjust your tp during your travel day. The intent is to start each day with the correct CIP.

6. If you run a TPMS, which I strongly recommend, you will see your tp go up and down during the day. This is normal and should be of no concern unless you see a drop below your CIP. I set my TPMS warning level at 5 psi below the CIP


Go to my homepage if you want to learn more about proper care loading and inflation from a tire design engineer.
__________________
Tireman9 is offline   Reply With Quote
Old 10-29-2016, 12:43 AM   #35
Tbo
1 Rivet Member
 
2001 25' Safari
Napoleonville , Louisiana
Join Date: Mar 2014
Posts: 14
The Goodyear load limit and pressure chart for the Marathons shows my size tires will carry 2020 lbs each at 45 psi. That's an 8000 lb capacity on 4 tires. My 25' Safari max weight is 6500 lbs so 45 psi is plenty enough pressure and a less damaging ride over the bumps. But the outer treads WILL wear first at that pressure.
__________________
Tbo is offline   Reply With Quote
Old 10-29-2016, 07:27 AM   #36
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 539
Quote:
Originally Posted by Tbo View Post
The Goodyear load limit and pressure chart for the Marathons shows my size tires will carry 2020 lbs each at 45 psi. That's an 8000 lb capacity on 4 tires. My 25' Safari max weight is 6500 lbs so 45 psi is plenty enough pressure and a less damaging ride over the bumps. But the outer treads WILL wear first at that pressure.
I think you have that backwards. Too much pressure wears the centers, not the shoulders.

- BUT -

My experience with radial tires is that the wear is relatively insensitive to pressure - that the old idea that overinflating a radial tire produces center wear is exaggerated - that there are other things that will have a greater effect and the pressure shouldn't be a concern (at least concerning wear!)

Besides, time is much more likely to be the reason to remove the tires, not wear (unless there is an alignment problem.)
__________________
CapriRacer is offline   Reply With Quote
Old 10-29-2016, 07:43 AM   #37
Rivet Master

 
2014 20' Flying Cloud
Long Island , New York
Join Date: Jun 2015
Posts: 3,035
Thanks for everyone's experience and suggestions -- Tireman9, CapriRacer, Phoenix, and everyone else.

FYI Tireman9 has an interesting site -- RVTireSafety [dot] com.

Happy and Safe Trails to all!

Peter
__________________
OTRA15 is offline   Reply With Quote
Old 10-30-2016, 09:59 PM   #38
Rivet Master
 
Ravenna , Ohio
Join Date: Apr 2012
Posts: 589
Quote:
Originally Posted by Tbo View Post
The Goodyear load limit and pressure chart for the Marathons shows my size tires will carry 2020 lbs each at 45 psi. That's an 8000 lb capacity on 4 tires. My 25' Safari max weight is 6500 lbs so 45 psi is plenty enough pressure and a less damaging ride over the bumps. But the outer treads WILL wear first at that pressure.
Could you help educate some of the others here and publish your four individual tire loads? Just so they understand that the sticker info of GAWR is not the same as actual tire loading.
__________________
Tireman9 is offline   Reply With Quote
Old 10-30-2016, 10:19 PM   #39
Rivet Master
 
switz's Avatar

 
2014 30' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 4,314
Images: 8
The information below is from my 2015 23D International Serenity loaded for camping after many modifications and not attached to my 2007 Mercedes ML320 CDI diesel tow vehicle. I used my two sets of four individual wheel weight scales to ascertain the actual weights by location on the trailer.

The stock 3,000 pound rated axles are used. The stock 14" GYM tires were upgraded to Michelin LTX (P) 235/75R15 XL tires with a sidewall rating of 2,183 pounds @ 50 psi but must be derated to 1,985 pounds for trailer use. They are mounted on 15" five lug nut SenDel T03-56545T wheels rated 2,150 pounds at 60 psi. The air pressure is set at 44 psi which provides maximum load capacity for this specific model tire.

Tongue………928
Front….1,280……1,246 - total front axle 2,526
Rear…..1,376……1,233 - total rear axle 2,609
Total Axles………………………………….5,135
Total Trailer….6,063

The street side of the trailer is heavier due to the solar system controller, Magnum hybrid MSH-3012 inverter and 300 amp-hour lithium battery being installed under the sofa and dinette seat outboard of the original dividers and forward of the wheel well.
__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels
switz is offline   Reply With Quote
Old 10-31-2016, 12:55 AM   #40
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 6,510
Images: 1
Is the above with the trailer hitched and WD applied?


1990 35' Silver Streak
2004 555 Cummins
__________________
1990 35' Silver Streak Sterling; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 10-cpm solo, 18-cpm towing
Sold: Silver Streak Model 3411
slowmover is offline   Reply With Quote
Old 10-31-2016, 08:46 AM   #41
3 Rivet Member
 
dcasr's Avatar

 
1990 29' Excella
Stone Mountain , Georgia
Join Date: Jul 2010
Posts: 168
Quote:
Originally Posted by switz View Post
... I used my two sets of four individual wheel weight scales to ascertain the actual weights by location on the trailer......
Switz, tell us a little more about the individual wheel weight scales. Where did you get them? How expensive are they? How exactly do you use them, do you jack up one wheel at a time and put the scale under the tires one side and then the other? If you have four of them you must have all four deployed at once.

I have a tongue weight scale that works great, but this is the first I have heard about individual wheel scales, so tell us everything about them. Thanks +dcasr
__________________

1990 Excella 29' Centramatics
2016 GMC Sierra Crew Cab 2500 HD 4x4
6.6L Duramax + Allison, 3.73 axles
dcasr is offline   Reply With Quote
Old 10-31-2016, 09:39 AM   #42
Rivet Master
 
switz's Avatar

 
2014 30' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 4,314
Images: 8
As mentioned in the first sentence in my post, the trailer was not connected to the tow vehicle. Those numbers reflect it just parked on a level surface all by itself.

The scales are the 5,000 pound model per scale with one pound increments in the read out. One needs to contact those folks to see if they still make that version and acquire about current pricing. I have two sets of four scales and each set has it's own control head and printout capability.

http://www.scaleline.com/pww-13k.htm
__________________

__________________
WBCCI Life Member 5123, AIR 70341, 4CU, WD9EMC

TV - 2012 Dodge 2500 4x4 Cummins HO, automatic, Centramatics, Kelderman level ride airbag suspension, bed shell

2014 31' Classic model 30 twin beds, 50 amp service, 900 watt solar system, Centramatics, Dill TPMS, disc brakes, 16" tires & wheels
switz 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
Water Pressure: Shore pressure high, All pressure in trailer low.... bhooves Sinks, Showers & Toilets 9 10-16-2016 04:22 PM
High Pressure vs. Low pressure Appliances emenriquez General Appliance Topics 2 06-15-2009 02:04 AM
Tire Pressure Gauges- Pressure Varies! Ray Eklund Tires 14 07-06-2008 09:34 AM
Canadian Tire's $129 Tire Pressure Monitoring System SilverCottage Tires 9 10-30-2007 08:55 PM
Low pressure / High pressure appliances Rick LP Gas, Piping, Tanks & Regulators 1 06-15-2002 07:29 PM


Virginia Campgrounds

Reviews provided by



Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 10:33 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.

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