Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-27-2014, 10:39 AM   #827
Don't forget your cat nap
 
Ag&Au's Avatar
 
Port Orchard , Washington
Join Date: May 2009
Posts: 4,464
Images: 1
Quote:
Originally Posted by CapriRacer View Post
Yes, that is what I am saying.



Because:

1) That is MY recommendation

2) The confusion would not be eliminated because there would now be 2 charts with different loads on them.



No, that 10% is NOT part of my recommendation. It is a separate issue - the standard way of dealing with P type tires used in LT and trailer service.

To put it distinctly, the load carrying capacity of a P type tire has to be reduced by 10% to get the load carrying capacity when the tire is used on Pickups, vans, and trailers - and then another 15% reduction per my recommendation.



Not exactly.

When I was in college, I had a professor who said "Overdesign, underutilize". What he meant was that products need to be overdesigned to accommodate those things we engineers don't know about when we design stuff - and when those products are used, they should be used at a lower level to also accommodate those things we don't know about the intended usage.

What reducing the published load from the tables by 15% does is part of the "underutilize" part of the equation.
Thanks for taking the time to explain the origin and the reason for those numbers. It make it much easier to arrive at an informed decision.

The one thing that is obvious from this thread is: There is no way to be absolutely safe from tire failure. If if the engineers do their job and the user is diligent in his selection, a malfunction in a manufacturing or chemical plant, can still produce a substandard tire. As illustrated by the Michelin and other recalls, the user is the ultimate tester. Even if we could make tire manufacturing 100% reliable, there is still the issue of road hazard.

The take away for me is to exercise maimum diligence in selecting your running and towing gear and inspect it often and hope your inspections reveal faults before they cause failure. Keep all this in mind and then find a thought process that allows you to still enjoy the drive,

Ken
__________________

__________________
Ag&Au is offline   Reply With Quote
Old 11-27-2014, 01:28 PM   #828
Rivet Master
 
switz's Avatar

 
2014 31' Classic
2015 23' International
2013 25' FB International
Apache Junction , Arizona
Join Date: Sep 2012
Posts: 4,799
Images: 8
Seeing that Airstream shipped our 2014 Airstream 31' Classic with four 15" Goodyear Marathons (ST225/75R15D ) rated 2,540 pounds at 65 psi each (four tires equals 10,160 pounds capacity) and the GVW is 10,000 pounds, they do not appear to be following the safety margin concept very closely.

In our specific case, our tongue weight is about 1,345 pounds which would mean the tires could be carrying 8,635 pounds at GVW. The four 15" Michelin LTX (P) 235/75R15 XL tires are derated to 7,940 pounds (side wall load rating would be 8,732 pounds). They would be of inadequate load capacity at GVW.

One tends to overlook the weight loading when parked, but the tires, axles and tongue jack are supporting the GVW then. So the correct tire size helps....

Maybe that is why Airstream is putting the SenDel T03-66655T wheels and Michelin LT225/75R16/E LTX M/S2 tires on the 2015 Classics as standard tires. Four tires are rated 10,720 pounds at 80 psi.
__________________

__________________
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 11-27-2014, 06:29 PM   #829
Moderator dude
 
Action's Avatar

 
1966 26' Overlander
Phoenix , Arizona
Join Date: Apr 2002
Posts: 6,067
Images: 13
Quote:
Originally Posted by switz View Post
Seeing that Airstream shipped our 2014 Airstream 31' Classic with four 15" Goodyear Marathons (ST225/75R15D ) rated 2,540 pounds at 65 psi each (four tires equals 10,160 pounds capacity) and the GVW is 10,000 pounds, they do not appear to be following the safety margin concept very closely.
While the tongue weight will take some load, I would suggest price is a factor in this example.

>>>>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 11-27-2014, 06:44 PM   #830
Rivet Master
 
Gene's Avatar
 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 10,840
Airstream is very, very slowly converting to Michelins with 16" wheels. When I discussed Michelins with them at least 5 years ago, they were starting to offer them as a barely disclosed option. They did have a display with 16" wheels and tires at the office then. I think they offered a Goodyear LT tire and maybe also Michelin. I ended up trading OEM wheels with them, picking up 16" Michelin LTX tires at Discount Tire in Dayton, and having Airstream install it all. The OEM 15" wheels looked bad as the coating was failing and I got new wheels at a substantial discount. The tire distributer had a one year warranty and wouldn't cover it as I was over the one year.

Over time, Airstream has made the Michelin 16" LTX tires more and more available as either an option or on specific models. Michelins cost about 2 times more than Marathons and larger wheels must cost a little more. But the Goodyear LT option is gone and they have, at least in this instance, listened to customer about Michelins.

Though Michelin had a recall, they didn't stall or try to limit it—they did it on their own and it must be costing a mint. Unfortunately we were out of the recall period as I was hoping for all new tires.

And yes, you have to make the decision yourself based on all available knowledge, trying to sort through the crap to figure out the best thing to do. That is something we have to do with everything, every day. I wish there were easy answers and better research. RV research on many things is weak or nonexistent as there's little money in it.

I am getting close to 5 years on the Michelins and they have lots of tread left. Many here have recommend tires should be replaced at 5 years because of aging (by that standard, I should have been replaced generations ago). Michelin has been quoted as saying 10 years so long as they are regularly inspected. It has been said elsewhere on this Forum that Michelin says 7 years, but I couldn't find anything definite on their website. The 10 year quote comes from Edmunds' website. Regardless of how old they are, regular inspections are a good idea. I don't know where the 5 year rule comes from—it may be "conventional wisdom", thus repeated so often it is believed to be true. I get 65-75,000 miles on Michelins on motor vehicles and that is often more than 5 years, though not by much. Because there are no drive wheels on a trailer, I expect them to last for even more miles.

Gene
__________________
Gene is offline   Reply With Quote
Old 11-27-2014, 07:56 PM   #831
Moderator
 
moosetags's Avatar

 
2015 25' FB Flying Cloud
2012 23' FB Flying Cloud
2005 25' Safari
Santa Rosa Beach , Florida
Join Date: Jul 2006
Posts: 10,762
Images: 5
That has been about my experience, Gene. Old Lucy had her 16" Michelins for four years. We put 60,000 miles on these tires. They showed no discernible tread wear.

We have already gotten the Michelins on New Lucy. The tires and wheels cost us $1,600. We were able to sell New Lucy's OEM tires and wheels for $600. Therefore, the upgrade cost us a total $1,000.

I would think that Airstream could offer a Michelin option for $1,000 or less.

Brian
__________________
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2018 Silverado 2500 (Lillian)
moosetags is offline   Reply With Quote
Old 11-27-2014, 10:17 PM   #832
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 7,583
Images: 1
16" wheels/LT tires

Tires that do not spend regular time on the road deteriorate more quickly. Exercise redistributes oils within the rubber. This is the problem with trailer tires and why standard manufacturer recommendations may not apply.

Going with premium tires doesn't change TT replacement schedule greatly given differences for local and individual owner conditions.

I'd check Tireman9's blog and ask advice. Whether a Michelin dealer knows exactly what to look for during a dismount would be key.

Michelins have been known to look fine on outside and not on the interior. This happened to the five year old ones on my truck (2007-2012) with only 80k on them. Three out of four failed on a trip back from San Antonio. I was practically given a new set. Had 4/32's total wear and was looking to take them well past the 120k mark that the original set had delivered.

Reading around I believe this was a problem over a few years that has since been rectified.

Three to five years is the usual recommendation due to service. Were I making a few short trips in cooler weather I'd inspect and go on. But extended touring would be something else again.
__________________
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 online now   Reply With Quote
Old 11-28-2014, 07:14 AM   #833
CapriRacer
 
CapriRacer's Avatar
 
I'm in the , US
Join Date: Sep 2012
Posts: 624
Quote:
Originally Posted by BoldAdventure View Post
What if the tire engineers already did that in the design process and have factored in 15% already? Now we're at 30%?.....
Then tires wouldn't be failing and you wouldn't worry about it.

Quote:
Originally Posted by BoldAdventure View Post
.....This is just based on a personal preference as the 15% seems to be an arbitrary number you came up with correct?.......
No.

When the Ford/Firestone thing was active (winter of 2000/2001), the company I worked for examined all the tire failures they had on record and discovered that most of the tire failures were coming from SUV's and pickup trucks - where there was no reserve tire capacity (unused tire capacity).

Cars, on the other hand, had very few failures. They also generally had about a 15% reserve. What was even more interesting was that SOME SUV's had a 15% reserve capacity and those tires behaved like the ones on cars

So the company I worked for recommended to all the car manufacturers that it was doing business with that all vehicles have a 15% reserve tire capacity - and most followed through, in particular, Ford. (I have to assume, other tire manufacturers did the same sort of analysis and came to the same conclusions as there didn't seem to be any pushback from the OEMs.)

The result was a drop in the rate of tire failures (although it was hard to sort this out as there were changes on the tires taking place at the same time)

So, No, the number is not arbitrary. It is based on personal experience.
__________________
CapriRacer is offline   Reply With Quote
Old 11-28-2014, 07:52 AM   #834
Full Time Adventurer
 
BoldAdventure's Avatar
 
2007 27' International CCD FB
Nomadic , USA
Join Date: Jul 2013
Posts: 2,743
Ok, great to know then.

So the Michelin LTX M/S2 in 225/75R16 rated at 2680 lbs. with 80 psi.

Derated 10% for Trailering = 2420 lbs. and with a safe margin of 15% = 2057 lbs.

2057 lbs. x 4 tires = 8228 lbs rating.

Which means trailers with 10,000 GVWR running these would be way over a safety margin based on above advice. ??

----------------

Unless the math is 15% & 10% from the original rating. At which it becomes 2010 lbs rating x 4 tires = 8040 lbs.

Either way, this all works out for my trailer math wise. But for others????

But this completely kills it on the 15's.

Michelin LTX M/S2 in 235/75R15 at 50 psi. rated at 2183 lbs.

Derated 10% for trailering = 1964 lbs.
Derated 15% safety = 1669 lbs

1669 x 4 tires = 6676lbs rating.
__________________
Family of 4 living, working & exploring the USA in our Airstream.
OUR BLOG | FACEBOOK | INSTAGRAM
BoldAdventure is offline   Reply With Quote
Old 11-28-2014, 08:59 AM   #835
Rivet Master
 
Al and Missy's Avatar

 
2002 30' Classic S/O
Melbourne Beach , Florida
Join Date: Nov 2013
Posts: 2,319
The 10% derating factor is only applied to p-metric tires, and it is an NHTSA and/or MVSS requirement, not just a rule of thumb.

Also, unless I am mistaken, the load limit applies to the weight the tires are carrying, not the GVWR, so subtract off the actual tongue weight.
__________________

"You cannot reason someone out of a position they have not been reasoned into"

Al, K5TAN and Missy, N4RGO
2002 Classic 30 Slideout
S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins
2001 Safari 25 RB Twin (Gone, but not forgotten)
WBCCI 1322, TAC FL-39, AIR 82265

Al and Missy is offline   Reply With Quote
Old 11-28-2014, 09:13 AM   #836
Rivet Master
 
SteveSueMac's Avatar

 
2012 27' Flying Cloud
W , New England
Join Date: Oct 2012
Posts: 5,410
Quote:
Originally Posted by BoldAdventure View Post
Ok, great to know then.

So the Michelin LTX M/S2 in 225/75R16 rated at 2680 lbs. with 80 psi.

Derated 10% for Trailering = 2420 lbs. and with a safe margin of 15% = 2057 lbs.

2057 lbs. x 4 tires = 8228 lbs rating.

Which means trailers with 10,000 GVWR running these would be way over a safety margin based on above advice. ??

----------------

Unless the math is 15% & 10% from the original rating. At which it becomes 2010 lbs rating x 4 tires = 8040 lbs.

Either way, this all works out for my trailer math wise. But for others????

But this completely kills it on the 15's.

Michelin LTX M/S2 in 235/75R15 at 50 psi. rated at 2183 lbs.

Derated 10% for trailering = 1964 lbs.
Derated 15% safety = 1669 lbs

1669 x 4 tires = 6676lbs rating.
Not exactly. The 16s are LT not P tires. No derating required so you're getting over 10700# capacity - then with the 15% safety margin you have over 9100# available.

Next, that's capacity for your weighed trailer. Your max GVWR is just that - a max. When you're on the scales, you'll see what your trailer axles actually see loaded for camping. For example, my GVWR is over 7000# but loaded for camping, the scales show 5800# on the trailer. While it would be great to get each wheel weight individually, I'm happy knowing the 4 tires are sharing 5800#.

If your GVWR is 10,000, your actual towing weight could be 7500ish (weighing it is the only way to know for sure). That's the capacity you need to worry about. Anything under 9100# would work for you with those 16s.
__________________
SteveSueMac is offline   Reply With Quote
Old 11-28-2014, 10:54 AM   #837
Rivet Slave
 
Rocinante's Avatar

 
2014 27' FB International
Western WA , Washington
Join Date: Dec 2013
Posts: 3,440
Blog Entries: 49
16" wheels/LT tires

Ok, so how about these General Grabber HTS tires for 15" wheels? They seem to have a higher rating than the Michelin 15" tires, which according to the Michelin site are rated for only 1985 pounds. The 109T rated General Grabber HTS in 235/75R15 XL is rated at 2271 pounds with max inflation pressure of 51 pounds. If that's a good tire, it would seem a better choice than the lower-rated Michelin...unless I am misunderstanding, which is entirely possible.

Oh, and the General is a "low rolling resistance" tire, which sounds like it might be helpful for better MPG when towing.

http://www.michelinman.com/tire-sele...ails#techspecs
http://www.generaltire.com/tires/lig...bber-hts#Specs

Thoughts?
__________________
Rocinante is our 2014 International Signature 27FB
(Named for John Steinbeck's camper from "Travels With Charley")


Rocinante is offline   Reply With Quote
Old 11-28-2014, 11:10 AM   #838
Vintage Kin
 
slowmover's Avatar
 
Fort Worth , Texas
Join Date: Nov 2006
Posts: 7,583
Images: 1
To be thorough trailer tire load need also take into account, when parked, the additional weight of supplies and people aboard. There are those who travel without fresh water, for example.
__________________
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 online now   Reply With Quote
Old 11-28-2014, 11:20 AM   #839
Full Time Adventurer
 
BoldAdventure's Avatar
 
2007 27' International CCD FB
Nomadic , USA
Join Date: Jul 2013
Posts: 2,743
I read him wrong on the derating 10%, thought he was applying it to LT tires too. I know the rating is what it's actually carrying, not GVW, but I'm using it as a measure. I know I could use P tires right now, but maybe not when we go full time.

slowmover I've owned General Tires on several vehicles. I like them, good tire. Can't speak to putting them on Airstreams.
__________________
Family of 4 living, working & exploring the USA in our Airstream.
OUR BLOG | FACEBOOK | INSTAGRAM
BoldAdventure is offline   Reply With Quote
Old 11-28-2014, 11:58 AM   #840
Don't forget your cat nap
 
Ag&Au's Avatar
 
Port Orchard , Washington
Join Date: May 2009
Posts: 4,464
Images: 1
Quote:
Originally Posted by slowmover View Post
To be thorough trailer tire load need also take into account, when parked, the additional weight of supplies and people aboard. There are those who travel without fresh water, for example.
I would have to think about this concept for a while before I accepted it. Tires are rated for moving at their max rated speed and the associated flexing, scuffing and heating involved. When sitting still in a campground or wherever, none of those dynamics are occurring, and a certain amount of the weight is being born by the tongue jack. So my instincts tell me what happens when parked is not a factor. (within reason of course).

If I am misinterpreting what you said, then "never mind" .

Ken
__________________

__________________
Ag&Au is offline   Reply With Quote
Reply

Tags
16" tires, ltx


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
15" to 16" Wheels/Tires on 2007 Safari Rollertoaster Tires 53 01-23-2011 07:41 AM
Wheels and Tires shepherd57 Argosy Motorhomes 7 08-09-2010 08:14 PM
16" 5 on 5 1/2 wheels - What tires? Benjo Tires 10 02-15-2010 08:41 PM
New wheels and tires upgrade to 16" & Michelin Tin Diesel Wheels, Hubs & Bearings 9 04-23-2008 11:48 AM
Wheels and Tires Fordstream Tires 4 01-12-2006 10:51 PM


Virginia Campgrounds

Reviews provided by




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:23 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.