Reply
 
Thread Tools Search this Thread Display Modes
 
Old 02-27-2012, 02:44 PM   #15
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 3,633
Quote:
Originally Posted by CrawfordGene View Post
Jammer,
One thing not considered is the frequency of tread separation with Marathons and possibly with other ST tires vs. the LT tires— is it caused by low manufacturing standards for ST tires? It is suggested, but not explicit. I think ST tire manufacturers may think people only tow trailers short distances every year and the ST's don't have to have standards for heavy use.
They talk a lot about this in that thread.

It's difficult for us to take a scientific approach to this here at airforums because it's never an apples to apples comparison. When people switch to LT tires they also switch to larger tires, and so we don't, based on the real-world Airforums Experience, know whether the lack of tread separation is due to the fact that the tires are larger, or the fact that they are LT rather than ST.

The tire engineer in the thread, to comply with the conditions of his employment, doesn't identify which tire manufacturers he has worked for. But he's been in the industry for decades, he says, and I don't have any reason to doubt that. He says that the manufacturing standards and internal construction for ST and LT tires are, broadly, the same, as he understands it, although he has not worked in the industry on any ST tire projects in particular.

Of course, ST tires have a higher load rating than LT tires of the same size at the same inflation pressure. This is supposed to be justified by the difference in use with trailer service being less demanding, and to some extent by the shallower tread depth which helps somewhat with cooling.

Another way to look at it is that if you believe the LT load ratings are the correct ones to use for the situation then in most cases you're overloading your ST tires, because there is a 10-15% increase in maximum load from the LT tires of the same size and ply rating.

Quote:
It appears to me (just guessing) that a lot of us here do travel a lot and may have worse experiences than the average RV owner—speculation city of course.
The rvforum.net and rv.net forums (unrelated to each other) are full of complaints about trailer tires. The only common denominator is that the complaints mainly come from the sun belt, and people who switch to larger rims so they can mount larger LT tires become happy thereby.

Quote:
Next is whether specific brands are better, all other things being equal. I realize all things are never equal, but I will continue. My experience with Michelins is they have good traction right up to the time tread wear indicates replacement. They also ride smooth and last a long, long time. That alone is a good reason to choose them.

....

It is interesting that it was said ST and LT tires are not constructed too differently. But maybe manufacturers make them differently. Michelin does not make ST tires. Maybe the comparison was between Goodyear LT's and ST's.
Apparently the differences in treadwear by brand have much to do with car manufacturers, who place great emphasis on traction and rolling resistance and little emphasis on treadwear in their purchasing decisions. Tires originally developed for the OEM market therefore have poor treadwear. Many of the tires sold by Goodyear and Firestone in the replacement market are identical to those they supply to OEMs, while the same is less true for Michelin.

I've never heard anyone complain about the treadwear for ST tires -- one of the few areas where there is a clear difference in construction. It's belt separation failures that people complain about. But the tire carcasses are, supposedly, the same.
__________________

__________________
Jammer is offline   Reply With Quote
Old 02-27-2012, 03:34 PM   #16
Rivet Master
 
2005 19' Safari
Phoenix , Arizona
Join Date: Aug 2004
Posts: 1,969
"When people switch to LT tires they also switch to larger tires, and so we don't, based on the real-world Airforums Experience, know whether the lack of tread separation is due to the fact that the tires are larger, or the fact that they are LT rather than ST."

"ST tires have a higher load rating than LT tires of the same size at the same inflation pressure. This is supposed to be justified by the difference in use with trailer service being less demanding, and to some extent by the shallower tread depth which helps somewhat with cooling."

I disagree with these statements. We switched from 225/75x15 to 225/75x16 (both load range E tires) which are very close in size and load rating. The main difference is the change from ST to LT tire construction.

"I've never heard anyone complain about the treadwear for ST tires -- one of the few areas where there is a clear difference in construction. It's belt separation failures that people complain about. But the tire carcasses are, supposedly, the same."

The reason there are very few treadwear complaints on ST tires is that they either fail due to tread separation or blowouts, or are replaced due to age; and they don't survive to go bald.

As for ST and LT tires being constructed the same, I examined my failed Goodyear Marathon carcasses; and I found the sidewalls to be constructed of extremely large cords that looked like they were dipped in rubber. The closest analogy I can describe is heavily coated tent fabric, soft and floppy; and they felt more like bicycle tires on steroids, than any tire one would find on an automobile or pickup.

While I have not examined an LT tire carcass that has blown out in similar fashion, both new and used LT tire sidewalls are much stiffer and rigid. And, there is no comparison between the Marathon and XPS Rib sidewalls.

After handling NEW Michelin M/S2 and XPS Ribs LT tires (before installation), versus NEW Marathon, Carlisle and Maxxis ST tires, there is no doubt which I would rather run on our Bambi.
__________________

__________________
Phoenix is offline   Reply With Quote
Old 02-27-2012, 06:03 PM   #17
Rivet Master
 
Gene's Avatar

 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 9,735
ST tires, it has been said more than once on the Forum, have more rigid sidewalls than LT's—as does the Rib. If you back a trailer with ST tires at an extreme angle (just before you crush your taillight lens on the trailer), ST tires don't give and they skip sideways. Maybe that accounts for "the sidewalls … constructed of extremely large cords that looked like they were dipped in rubber". LT tires don't skip like that (at least, I haven't been able to do it). They bend—eventually they would either come off the wheel or they would slide on the tread I guess.

ST tires are designed with stiff sidewalls to prevent trailer sway. That was, I believe, a big reason they were invented years ago. When radials came out they had soft sidewalls compared to bias ply. I suppose people started using radials on trailers and had problems, so the ST tire was created. Maybe few people used sway bars or weight distributing hitches in those days. Now almost everyone does—well, almost everyone who posts on this Forum.

This seems to be a significant difference in construction. The tire engineer may not really understand ST's: "he has not worked in the industry on any ST tire projects in particular". But it doesn't account for tread separation. Do the people reporting separation primarily live in hot climates and drive at 65 or higher for hour upon hour? Jammer reports that on other Forums most of the problems are from people in hot climates. Are the ST's designed for people towing at 45 mph on the blue highways and only sometimes getting on an expressway?

It is true OEM car and truck tires wear badly. The companies buy them because they are cheap and certainly they want to the buyer to think their vehicle rides like their living room sofa. I have gotten Michelins on new vehicles and they wore great, so not all OEM tires are bad. Ironically our Tundra came with Michelin's cheap brand, Goodrich P tires, Load Range C. They wore fast and didn't ride all that smoothly. I replaced them with Michelin LTX A/T2, Load Range E, and they ride better than the Goodrichs and are going strong at 50,000+ miles.

One more thing. Drive tires—the ones connected to the engine—wear faster than all others. Trailers don't have drive tires, so they last longer. I don't have to rotate them as frequently either.

Gene
__________________
Gene is offline   Reply With Quote
Old 02-27-2012, 06:43 PM   #18
Rivet Master
 
Coloradobus's Avatar
 
Join Date: Jul 2003
Posts: 723
Now there is NEW tire on the market
February 27, 2012 by RV Business

Omni-United has launched the Radar Angler RST 21, a new tire specially designed for travel trailers, boat trailers and pop-up campers.
The Angler RST21, said the company, features a “unique tread pattern with a solid center rib to ensure stability under heavy loads, open tread shoulders for water dissipation while traveling under wet conditions, and an extensive size range from 13- to 16-inch wheel diameters.”
The new tire is currently available in sizes ST175/80R13, 205/75R14, 215/75R14, 205/75R15, 225/75R15, 235/80R16, and 235/85R16.
For every Radar-brand tire sold, Omni United will donate 25 cents to the Breast Cancer Research Foundation (BCRF). The BCRF is a New York-based non-profit that funds clinical and translational research into finding a cure for breast cancer.
__________________
JIM n CHRIS
'90 SquareStream 29ft, "62 ATW Overlander, '51 Flying Cloud
'67 GT, '06 Bambi, Bigfoot slide in/Dodge truck, .52,000 lbs SOB Class A.
Coloradobus is offline   Reply With Quote
Old 02-27-2012, 06:45 PM   #19
Rivet Master
 
2005 19' Safari
Phoenix , Arizona
Join Date: Aug 2004
Posts: 1,969
Some data from last year's tire failure poll:

* Do the people reporting separation primarily live in hot climates...?
- Freezing to 70 degrees F = 9 responses reporting tire failures
- 70-90 = 31
- 90-110 = 7
- 110+ = 1

*... And drive at 65 or higher for hour upon hour? -- Unfortunately, the tire poll did not include a question regarding average cruising speed.

* Jammer reports that on other Forums most of the problems are from people in hot climates. -- This does not seem to be the case for Airstream owner responses in the poll.

Other interesting data from poll:

* Tire pressures
50 psi = 10 responses
55-60 = 6
65 = 38
72 = 1
80 = 1

* Tire manufacturers of failed tires:
Goodyear Marathon = 40 responses
Carlisle = 3
BF Goodrich = 2
Michelin = 1
Other brands (not specified) = 4
__________________
Phoenix is offline   Reply With Quote
Old 02-27-2012, 08:33 PM   #20
Silver Mist
 
LI Pets's Avatar
 
1977 31' Sovereign
Riverhead , New York
Join Date: Aug 2006
Posts: 3,008
Images: 28
Quote:
Originally Posted by Coloradobus View Post
Now there is NEW tire on the market
February 27, 2012 by RV Business

Omni-United has launched the Radar Angler RST 21, a new tire specially designed for travel trailers, boat trailers and pop-up campers.
The Angler RST21, said the company, features a “unique tread pattern with a solid center rib to ensure stability under heavy loads, open tread shoulders for water dissipation while traveling under wet conditions, and an extensive size range from 13- to 16-inch wheel diameters.”
The new tire is currently available in sizes ST175/80R13, 205/75R14, 215/75R14, 205/75R15, 225/75R15, 235/80R16, and 235/85R16.
I can't find their dealer listing
__________________
Bob
'77 Sovereign Intl 31' CB
WBCCI R2 Rep VAC 11411 Metro NY VP

LI Pets is offline   Reply With Quote
Old 02-28-2012, 06:42 AM   #21
Silver Mist
 
LI Pets's Avatar
 
1977 31' Sovereign
Riverhead , New York
Join Date: Aug 2006
Posts: 3,008
Images: 28
I contacted the importer they are due in the US next week if the price is right, I may try a set.
__________________
Bob
'77 Sovereign Intl 31' CB
WBCCI R2 Rep VAC 11411 Metro NY VP

LI Pets is offline   Reply With Quote
Old 02-28-2012, 08:38 AM   #22
Rivet Master
 
r carl's Avatar
 
Vintage Kin Owner
Linc , Ne
Join Date: Dec 2009
Posts: 1,563
Quote:
Originally Posted by LI Pets View Post
I contacted the importer they are due in the US next week if the price is right, I may try a set.
If they are being imported from china you should already know what to expect of them.
__________________
r carl is offline   Reply With Quote
Old 02-28-2012, 09:29 AM   #23
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 3,633
Quote:
Originally Posted by Phoenix View Post
"When people switch to LT tires they also switch to larger tires, and so we don't, based on the real-world Airforums Experience, know whether the lack of tread separation is due to the fact that the tires are larger, or the fact that they are LT rather than ST."

"ST tires have a higher load rating than LT tires of the same size at the same inflation pressure. This is supposed to be justified by the difference in use with trailer service being less demanding, and to some extent by the shallower tread depth which helps somewhat with cooling."

I disagree with these statements. We switched from 225/75x15 to 225/75x16 (both load range E tires) which are very close in size and load rating. The main difference is the change from ST to LT tire construction.
A 225/75R16 tire has about 20% more load carrying capacity than an identical 225/75R15 tire because the air volume is that much larger. The load rating is similar in your case only because you switched from ST to LT. If you compare two LT tires in these sizes you'll see a larger difference.
__________________
Jammer is offline   Reply With Quote
Old 02-28-2012, 09:44 AM   #24
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 3,633
Quote:
Originally Posted by CrawfordGene View Post
ST tires, it has been said more than once on the Forum, have more rigid sidewalls than LT's [...]

ST tires are designed with stiff sidewalls to prevent trailer sway. [...]

This seems to be a significant difference in construction.
Reading through the thread, the engineer dude seems to be pretty confident that there's no difference in the sidewalls, and he specifically rebuts the "thicker cord" comments. I don't know who's right. ::shrug:: It may be that the observed behavior of the tires "skipping" in turns is due to a less grabby tread compound rather than a stiffer sidewall (my speculation).

Quote:
The tire engineer may not really understand ST's: "he has not worked in the industry on any ST tire projects in particular". But it doesn't account for tread separation. Do the people reporting separation primarily live in hot climates and drive at 65 or higher for hour upon hour? Jammer reports that on other Forums most of the problems are from people in hot climates.
To be fair, my observations are anecdotal, and there are more people with RVs in the sun belt than in northern areas, so that may distort what I perceive. But I've seen some fairly serious frustration among people in Texas, Arizona, and New Mexico -- multiple failures a year or multiple failures on one trip, or repeat problems with multiple brands -- that just doesn't seem to exist, at all, in the North. Industry wide across all tire types (not just ST) the incidence of tread separation failures seems to be around 1 per 1000 tires, and so I guess in that light the fact that I've done 30 years of driving with only one tire failure on the road (driving someone else's car at that) isn't exceptional.

In the motorhome-oriented forums there is also a certain amount of complaining about tires that goes on although perhaps not with the same enthusiasm with which people complain about trailer tires.

Quote:
Are the ST's designed for people towing at 45 mph on the blue highways and only sometimes getting on an expressway?
I think that's how they are rated. The K factor used in the ratings hasn't been changed since the introduction of the industry's first radial tires in the late 1960s.

Before 1973 none of the tow vehicles could tow over 65 mph. After that we had the 55 mph speed limit, until speed limits started going up in the 1990s.
__________________
Jammer is offline   Reply With Quote
Old 02-28-2012, 11:13 AM   #25
Rivet Master
 
Gene's Avatar

 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 9,735
Jammer, I think you are doing a good job of being careful about what you say because we are still trying to figure this out, and may be for a long time.

The comment about the ST's skipping may be that the tread is less grabby, not sidewall construction. A good point Jammer. Some tire history: When radials came out, one benefit was that they hold the road better on curves. The softer sidewall allows them to kind of bend—the tread stays in place and the sidewall moves. Great for cornering at high speed until the tread slips when the sidewall can't bend anymore. Then the tire really skids fast unlike the relatively slower skids with bias ply. I can't remember when I first had radials, but I do remember having fun with a TR4A with Perelli radials in the mid-60's. If I understand correctly, trailers came with bias ply tires long after radials were introduced and I assume that was because of the weaker sidewalls. Thus, it appears ST's filled a gap—stronger sidewalls than a standard radial, but the better fuel mileage and cornering of a radial. I still wonder about that tire engineer; he may be parroting his employer's line for some reason.

We are working with limited evidence and thus often resort to anecdotal reports, but that is what we've got. It does appear hot climates mean more tread separation. But hot is not confined to the Gulf states and the southwest. The upper midwest sees plenty of heat and it can be 100˚ in the northeast. The southwest may be worse on tires because speeds are higher and so are temps. We don't know what temp is too much—95˚, 105˚, 115˚? If you are driving west at 75 mph for hours, are the south facing tires more likely to have the tread come off? Higher speeds and temps mean higher pressure, but I guess it isn't enough to make up for underinflation (maybe max inflation for the particular tire does not mean much at 100˚ at 75 mph).

I remember the 55 mph limit, but it was often ignored. Since it went away in the mid-90's, speed limits keep creeping upward (and death rates downward). Americans have always had some contempt for speed limits and the 55 thing probably increased that opinion. If complaints about tread separation are increasing it may have to do with higher average speeds and more heat waves (many of the past 10 or 20 years have been the hottest on record), but it may be from increased ease of communications through internet forums. Thus with the evidence we have it is difficult to know if tread separation is getting worse or what the cause is.

There was a lot of speculation that when Marathons were made in China, their quality dropped. I don't think there was any real evidence of that. It is obvious that some Chinese products are garbage, but not all (my iPad works great). Some American products are bad too (many of us feel Airstreams are no longer made as well even though they are handmade in America). It depends on the company and who is doing quality control. China does not mean poor quality, but we can infer from a lot of poorly made Chinese products that Chinese products may be worse quality than something made elsewhere. An inference is an invitation to investigate and not much else. So it is possible that Marathons were always bad or mediocre, but forums increased the perception of poor quality. This just points out that deciding things about tires is risky business, but an important business and one we engage in with relish.

Gene
__________________
Gene is offline   Reply With Quote
Old 02-28-2012, 12:03 PM   #26
Wise Elder
 
Jammer's Avatar
 
2010 30' Classic
Vintage Kin Owner
South of the river , Minnesota
Join Date: Dec 2009
Posts: 3,633
Gene,

I agree that the data is thin and it is perilous to read too much into it.

One conclusion that I believe we can draw safely is that there is hundreds if not thousands of times more industry, press, and regulatory attention focused upon the light truck tires from the major manufacturers than there is focused upon trailer tires from whatever source. As such we can assert with great confidence that a tire like, say, the Michelin A/T2, is a safe, reliable tire when used on light trucks. Anything we might assert, good or bad, regarding GYMs, would be with less confidence. The data is too thin.

I think we can also assert that LT tires are safe and reliable in trailer applications up to their rated max load. I haven't seen any data, anecdotal or otherwise, of premature failures. While there may be handling differences vis a vis ST tires, I haven't seen any evidence to suggest that they pose a safety or longevity problem.

For my own sake I'm convinced that GYMs are a safe and reliable tire as long as they are inflated to the max pressure embossed on the sidewall and kept below about 85% of their rated load. With my trailer I can do that. I will admit that the evidence is thin on this point.

I also think there's ample evidence to conclude that the industry in general (not picking on Airstream in particular here) is under-specifying their GAWRs at least on some models -- and that this is contributing to tire failures.

Finally, I think that there's plenty of data to conclude that there is a safety benefit to switching to larger tires if the present tires are ST type and they are routinely loaded beyond 90% of rated load.
__________________
Jammer is offline   Reply With Quote
Old 02-28-2012, 12:13 PM   #27
Rivet Master
 
Gene's Avatar

 
2008 25' Safari FB SE
Grand Junction , Colorado
Join Date: Sep 2007
Posts: 9,735
Jammer, I agree with your conclusions with the exception of the 3rd paragraph—Marathons have too many failures for me to feel good about. "Feel good" is an admittedly subjective analysis, but the one many people feel good about.

Risk analysis is driven by the end result—with tires that means things like death, serious injury and a messed up trailer. Thus, given the nature of the risks ("messed up trailer" rates pretty high among Airstream owners), Marathons don't feel good because failure has a big and nasty payoff. Whether this passes an objective test, I don't know, but they don't pass the feel good test.

Gene
__________________
Gene is offline   Reply With Quote
Old 02-28-2012, 12:55 PM   #28
Rivet Master
 
2005 19' Safari
Phoenix , Arizona
Join Date: Aug 2004
Posts: 1,969
There may be more tire failures in the southern states, because we don't winterize our RVs and use them year-round. When northern area RVs are stored and snow covered, we are enjoying the great outdoors. Also, there are a lot of "snow birds" in the south in the winter, which probably increases the total trailer miles driven and tire failures reported for this area.

Personally, my wife and I enjoy winter camping more than summer, because there are very few insects, snakes, etc., and camping areas are less crowded or even unused. In fact, we have trouble remembering it's still winter up north, when daytime temps here are in the 60s and 70s here.

When we visit relatives in Colorado, it's a shock to leave home with all the windows down on a bright sunny day, and arrive in Denver a day or two later in a blinding snow storm; and then, camp in subfreezing temps most nights.

An additional comment: Even though our LT tires are capable of higher speeds, we still drive 55-60 mph when towing; because the new tires didn't change the handling characteristics of our rig. Also, lower speeds reduce white-knuckle driving and save fuel. We just enjoy the ride more when we don't have to worry about a blowout ruining our trip.

Also, when one reads truck and car forums, tire discussions usually involve improving cornering/stopping performance, wider/bigger wheels and tires, OEM tires wearing out early, etc. On this forum, it seems like our tire discussions always involve who had the latest ST tire blowout or tread separation failure, and what the alternatives are to replace it/them with better, more reliable tires.

Of the people who completed the tire failure poll, approximately half of the responses indicated that they had experienced a tire failure. To be fair, since all new Airstreams come with Goodyear Marathons, the poll may be skewed to that brand. However, a 50% failure rate would not be tolerated in any other consumer product. I don't understand why it seems to be accepted as the norm by trailer owners (not just Airstream). If tires of this quality were installed on passenger cars, SUVs, etc., this would be another Firestone fiasco.
__________________

__________________
Phoenix 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
'75 Argosy for salvage and parts drauchenberg Argosy Motorhomes 9 02-01-2013 11:48 PM
She's Cheap and Trashy Bambified 1961 - 1963 Bambi 43 06-07-2012 12:22 AM
Tambour On Kitchen Cabinets Hard To Open and Close JillyBean63 General Interior Topics 6 02-25-2012 08:55 AM
Problem w Gaskets on rear door storage access starcraft Exterior Storage Compartments & Access Doors 5 02-23-2012 05:16 PM
Fridge not running on shore power bike_addict Refrigerators 7 02-21-2012 02:48 PM





All times are GMT -6. The time now is 07:32 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.

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