Reply
 
Thread Tools Display Modes
Old 06-08-2016, 02:21 PM   #71
Commercial Member
 
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,145
You guys seem to have it figured out but let me put the icing on the cake.

Yes it is the air pressure in the tire that carries the load not the tire itself.

The Load/Inflation tables provide the MINIMUM cold pressure to use to support the measured load.

BUT

You really should have a margin on the tire load capacity. By regulation passenger tires require at least 9% above the max load for the vehicle. Since R service is almost always at or real near (or over ) the max load rating of a tire I STRONGLY suggest TT should have at least a 15% margin. in load capacity.

BUT

Again multi-axle TT are a unique animal so there are special considerations if there is a real engineer (not one that plays one on TV)

Whenever you make a turn, gentle or 90 degree backing, you are placing unique and high loads on the TT tires that your TV tires do not get exposed to. This because the tires are not rotating with their center-line pointing to the center of the radius.
This results in high "Interply Shear" You can read this Google on "interply shear tires" to learn more.

You can not eliminate this force unless you made the axles "steer" which is $$$$
You can lower the shear by increasing tire inflation.

So if you are running LR-D tires and only need 55 psi to support the load what should you do?

1. At least increase the inflation to 65. This will give you better load margin and will lower the interply shear.
2. To further decrease the shear you would need higher inflation i.e. 70 or higher.

You will not decrease your chance of Tread Separation by putting on LR-E tires but only running 65 psi. In fact putting on LR-E may cause other problems because the construction in a LR-E tire may be heavier which means more heat which is what accelerates the degradation of the belt rubber.

Back to my reccomendation.

Know your actual tire load. Individual tire info is best as few axles are 50/50 side to side.
Also few TT have 50/50 axle to axle load split.
Select the heavier end of an axle and use that number when consulting the Load tables to learn the MINIMUM inflation needed.

This inflation would be the Warning level on your TPMS.

Add at least 10% with 15% better to the inflation to provide a load capacity margin.

BUT if we really want to lower tire failure probability Increase the inflation to no less than the sidewall inflation. If that doesn't give you a 15% margin then go up in Load Range.

As you can see there are a number of items to be considered and selecting the inflation is a balancing act.

You note I didn't mention wheels. You must have wheels capable of supporting the heavier load. You should also have wheels that are rated for inflation at least equal to your cold inflation level.

All tires on an axle MUST have the same inflation. On multi axle trailers I suggest all tires have the same inflation.


OK so have I overloaded you enough?
__________________

__________________
.
I write a blog on RV tire application and safety and give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV
RV Tire Safety Blog
Tireman9 is offline   Reply With Quote
Old 06-08-2016, 03:23 PM   #72
Who Dares, Wins
 
doc73's Avatar
 
Join Date: May 2012
Location: Chester County, PA
Posts: 4,825
Damn this just got deep with diagrams and stuff..
__________________

__________________

Pat, Jen & Heather... Oh yeah and our trained attack trailer cat, Cinnamon-EOW 11/22/2017
2015 ChevyHD D-Max
2018 Artic Wolf 315tbh8
doc73 is offline   Reply With Quote
Old 06-08-2016, 03:39 PM   #73
Mod free 5er
 
Join Date: Mar 2008
Location: Concord, NC
Posts: 24,215
Good info, Thanks Tireman9.
__________________
OldCoot is offline   Reply With Quote
Old 06-08-2016, 03:46 PM   #74
Commercial Member
 
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,145
Some people simply will not do what I tell them to do.

They want to know the "WHY"

So I tell em.
__________________
.
I write a blog on RV tire application and safety and give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV
RV Tire Safety Blog
Tireman9 is offline   Reply With Quote
Old 06-08-2016, 04:19 PM   #75
Senior Member
 
Join Date: Sep 2010
Posts: 1,702
In your example you used a D rated tire and then said 70 or higher. This may confuse people and is not recommended.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K
__________________

2011 Flagstaff 831FKBSS
2010 F250 4X4 5.4L 3.73 LS
EQUALIZER E4 1200/12000
lbrjet is offline   Reply With Quote
Old 06-08-2016, 05:06 PM   #76
Commercial Member
 
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,145
Quote:
Originally Posted by lbrjet View Post
In your example you used a D rated tire and then said 70 or higher. This may confuse people and is not recommended.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K
You are correct. I failed to type...

3. If you go to 70 you would need to move to LR-E tires as LR-D max out at 65.
4. Once you cross the bridge to LR-E it would be nice to go to 80 to greatly lower the Interply Shear and to greatly increase the margin on load capacity. Again confirming the wheels are OK.



Sometimes, for me, some of the steps are just too obvious if someone reads the entire thread and has been doing research but you are correct that it looks like every post must stand by itself or someone will jump to the wrong conclusion.
__________________
.
I write a blog on RV tire application and safety and give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV
RV Tire Safety Blog
Tireman9 is offline   Reply With Quote
Old 06-08-2016, 05:51 PM   #77
Senior Member
 
Join Date: Sep 2010
Posts: 1,702
I agree running 80 when going from D to E. We were really discussing from C to E which many, many people do. I don't think it would hurt any to run 80 if your stock rim can handle 80, but i also think it is not going to hurt running 65. Only C's are needed for max trailer load so 50 psi. If I'm wrong please tell me.

I had planned on D's to replace my C's, my rim is stamped for a D rating max load and although the max psi is not on the rim ETrailer.com lists it at 65. When I needed tires they only had E's so I bought those instead and run 65 and have great success.


2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K
__________________

2011 Flagstaff 831FKBSS
2010 F250 4X4 5.4L 3.73 LS
EQUALIZER E4 1200/12000
lbrjet is offline   Reply With Quote
Old 06-08-2016, 10:22 PM   #78
Senior Member
 
Join Date: Feb 2013
Location: WI
Posts: 225
I'm currently shopping 235/80/16 E or higher tires currently for my new Wildcat 5th wheel. FR was kind enough to put Provider 235/80/16 E with a date code of 2013 on my new trailer. I can't find Sailun locally, considering XPS Ribs and the GY are just to pricey.

Since this thread started with Carlisle I'll bring those up. My local discount tire has their new tire model in which is a Radial Trail HD model.

Specs look interesting:
ST 235/80/16 LRE Max 3520 80psi 75MPH
ST 235/85/16 LRE Max 3640 80psi 75MPH
ST 235/85/16 LRF Max 3960 95psi 75MPH

I have 6000# axles and GVW of 12000#
__________________
2016 Wildcat 312BHX
2015 Silverado 3500HD
sugarjohnson is offline   Reply With Quote
Old 06-08-2016, 10:46 PM   #79
Commercial Member
 
Join Date: Jul 2013
Location: Akron, Ohio
Posts: 1,145
Quote:
Originally Posted by sugarjohnson View Post
I'm currently shopping 235/80/16 E or higher tires currently for my new Wildcat 5th wheel. FR was kind enough to put Provider 235/80/16 E with a date code of 2013 on my new trailer. I can't find Sailun locally, considering XPS Ribs and the GY are just to pricey.

Since this thread started with Carlisle I'll bring those up. My local discount tire has their new tire model in which is a Radial Trail HD model.

Specs look interesting:
ST 235/80/16 LRE Max 3520 80psi 75MPH
ST 235/85/16 LRE Max 3640 80psi 75MPH
ST 235/85/16 LRF Max 3960 95psi 75MPH

I have 6000# axles and GVW of 12000#
Assuming your actual loads are below GAWR (confirmed with scale weights and balanced side to side. Any of the options look ok

Sailun do not have a large dealer network so I understand that Internet and shipping tires to a store is needed many locations.

BTW what warranty is on the Carlisle's? Can you get Road Hazzard for reasonable price?
__________________
.
I write a blog on RV tire application and safety and give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV
RV Tire Safety Blog
Tireman9 is offline   Reply With Quote
Old 06-08-2016, 11:00 PM   #80
Senior Member
 
Join Date: Feb 2013
Location: WI
Posts: 225
I'm unsure of the warranty on the new Carlisle but yes the I could get the road hazard very cheap as I have done lots of business with my local DT. My loaded weight last time I weighed in was right around 11,000#. We travel pretty light and never with full tanks etc.

I would really like the XPS ribs but they come in at max load of 3042# and I would like a little more margin then that. I somewhat intrigued with the new Carlisle 235/85/16 LRF. That would be plenty of tire for me assuming the new design is not a time bomb!

Looks like the warranty is 2 years?
__________________

__________________
2016 Wildcat 312BHX
2015 Silverado 3500HD
sugarjohnson 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Virginia Campgrounds

Reviews provided by




ForestRiverForums.com is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 01:50 AM.