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Old 10-29-2015, 04:10 AM   #31
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There is no overload safety margin on ST tires, so they should carry a load of no more than 80 % of the max.....be at max cold tp.....when starting out....and stay below max speed rating....exceeding any of these numbers causes the sidewalls to break down and is cumulative over time.... slow down, whats the hurry your house is with you...
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Old 10-29-2015, 07:16 AM   #32
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Originally Posted by kandl View Post
Huh
2604WS =15" Tires! Huh! Youroo!!
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Old 10-29-2015, 10:44 AM   #33
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Originally Posted by accumack View Post
GyroGearloose, what was your actual loaded trailer weight on the scales?
Prior trip similarly loaded it came in a little over 6900lbs.
This surprised me because the dry weight is 5995lbs.
Where did all that weight come from? Important stuff I guess.
At 6900lbs, the outside tires are still overloaded by 314lbs on slow curves.

The reason we went with the 2015 model year was for cargo capacity.
There had been a 2014 2604WS on the lot that we almost bought, until I looked at the rating sticker. I don't remember the exact number, but the cargo capacity was something like 800lbs. I balked at that because it seemed too low. Forest River changed the axles on the 2604WS in 2015 and the cargo capacity roughly doubled to 1660lbs.

At 1660lbs cargo capacity, I'm not likely to ever be overweight.

However, this is irrelevant.
My point is that you should be able to load the trailer to full GVWR and not overload the tires. I'm not running near GVWR, and still my math says my outside tires will be overloaded on turns.

An outstanding question is whether the tire manufactures have allowances for this built into the ratings. I'm still trying to get a clear answer on this from a tire manufacturer, and an understanding of whether it's hand waving or a hard printed specification. The implication of the Carlisle document that calls for a 20% additional margin suggests that they don't build in a margin.
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Old 10-29-2015, 10:48 AM   #34
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Originally Posted by youroo View Post
Gyro,so you went from a 15" OE size tires to 14" tires and Rims? Youroo!!
Nope.
Trailer came with 14".

If somewhere I said 15, it was a typo.


This creates a problem with upgrading since there aren't a whole lot of LRD choices in my 205/75R14 size.
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Old 10-29-2015, 11:19 AM   #35
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Originally Posted by sail2liv View Post
There is no overload safety margin on ST tires, so they should carry a load of no more than 80 % of the max.....be at max cold tp.....when starting out....and stay below max speed rating....exceeding any of these numbers causes the sidewalls to break down and is cumulative over time.... slow down, whats the hurry your house is with you...
I agree with the 'whats the hurry'. One of the things I like about my trailer is that I tend to slow down and relax.

However, one of the interesting things about the overload question is that you don't have to be going fast. The 580lbs per tire of overload that I calculated occurs where the advisory speed (little yellow speed limit sign before a curve) is 20mph.
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Old 10-29-2015, 11:32 AM   #36
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Originally Posted by Gyrogearloose View Post
Thanks, youroo!

I've changed my tires to Kumho 857 trailer tires and raised the load rating to where it ought to be. In the process I made a new mistake. The Kumho's are size 205R14. I asked for 205/75R14 as recommended for my trailer. The new tires are 0.9" larger in diameter than I expected, which was not my intent. I'm now trying to figure out if this did any harm. The gap between the two tires was already small, and got smaller. This is my new concern.


Otherwise, I'm trying to raise awareness of the tire problem on trailers. It doesn't make sense that we all should buy a new trailer and immediately go out and buy new tires. And it doesn't make sense that the large number of reports of tire failures in RVs should be written off as pilot error by owners. This wouldn't be tolerated in cars owned by the same people...or by the NHTSA.


A friend of mine would call what I'm doing 'Tilting at Windmills'. Maybe this is futile; maybe not. :-)

NHTSA is constrained by its budget which is controlled by Congress. As such they have to prioritize when and on what items to conduct an investigation.
I think we can all understand that fatalities and personal injuries are more important than trailer damage or simple tire failure. BUT the other part of this is the number of actionable complaints on file.

In general the RV community are more interested in posting complaints on RV forums than in providing the information NHTSA needs.
If you have a failure you need to do a few things.
1. Record the vehicle VIN
2, record the full tire DOT serial (including the date portion of the serial)
3. Record the correct and complete tire size (15" is not correct nor is 225-14)
4. Record the tire Make & Brand (model name) "Radial" is not a Make or Brand but that is what some provide
5. Snap a few pictures of the tire in good sunlight and close up
6. Spend the 10 minutes it might take to file a complaint with NHTSA. They don' need to know your travel itinerary or the weather of the day or who you were visiting. Just the facts

When I review the few complaints on file I see missing DOT, wrong tire manufacturer, incorrect or only partial size and lots of unnecessary information
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Old 10-29-2015, 11:49 AM   #37
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General comment of tire loading and tire selection

1. Given that non RV TT applications generally have 12% to 20% load capacity margin I see no technical reason why TT should not have similar. This margin will accomidate the side loading issue.

2. You should try and get actual individual tire loading as almost no TT are 50/50 axle to axle or 50/50 side to side on an axle.

3. If you can't get individual tire laods then at least get individual axle loads then you can use a 47/53 load split to have reasonable laod split and use the 53% number when adding your margin.

4. If you plan on staying with ST type tires you need to realize that there are an increasing number of tire companies now making ST type tires with a speed rating marked on the sidewall (this is a letter symbol) Even with a 75 mph number I would never exceed that speed in RV application even if the tire is rated higher. (Lots of technical reasons)

5. Stop buying on loest initial cost and consider things such as warranty length. You might ask yourself why a MFG would not offer a warranty or limit it to 12 months while others might offer multi year warranty. Also consider and read the fine print or a Road Hazzard Warranty. This should eliminate to issues of punctures etc being an excuse for not honoring a warranty.

6. Remember that one of the things you are buyinf is a relationship so it does you little good to get tires from a company that has only a couple outlets 200 miles away.

7 If you are considering a switch from ST to LT type be sure you review all the items you need to consider. I have covered this in posts in my blog.

8. Have a good time with your RV
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Old 10-29-2015, 11:50 AM   #38
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Originally Posted by Tireman9 View Post
6. Spend the 10 minutes it might take to file a complaint with NHTSA.
I agree completely.

There are a lot of complaints about RV tires that show up in user groups and not in the NHTSA logs. And the quality of those complaints isn't great.

I did notice that my telephoned complaint to the NHTSA wasn't accurately transcribed by the NHTSA agent I spoke with, so perhaps its better to write out a complaint in advance so that it's clear, and then paste into the form on the NHTSA website.

In my case, I have gotten the attention of an NHTSA engineer and have provided the details of my trailer and my math at her request. I asked for a review of this issue and they seem to be proceeding down that path.

If my math or conclusions are wrong, I'll let everyone know.
If they're right, I'll also let everyone know.
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Old 10-29-2015, 04:46 PM   #39
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I heard back from Victoria at Etrailer.com.


I had described my calculation of repeated overloads on the outside tires when towing on curves and asked if etrailer was aware of any tires that fit my trailer that will tolerate those overloads.


The response: "I spoke with both of our tire providers and a company that does tire testing and I was unable to find any information regarding tire overloads experienced while turning. The company that tests tires told me that they do not test trailer tires for anything like what you are describing. "


What I get out of this is that the tires are not tested for repeated overloads as will occur on a tire that has no margin between static load and load rating. It appears then that there is no basis to assume that repeated tire overloading on curves is within the test limits of tires. The implication is that there needs to be a margin between static load and tire load rating so that the tire load stays within specs even during weight shifts on curves. This margin is absent with the factory tires on my trailer when fully loaded.
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Old 10-29-2015, 08:11 PM   #40
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Originally Posted by Gyrogearloose View Post
I heard back from Victoria at Etrailer.com.


I had described my calculation of repeated overloads on the outside tires when towing on curves and asked if etrailer was aware of any tires that fit my trailer that will tolerate those overloads.


The response: "I spoke with both of our tire providers and a company that does tire testing and I was unable to find any information regarding tire overloads experienced while turning. The company that tests tires told me that they do not test trailer tires for anything like what you are describing. "


What I get out of this is that the tires are not tested for repeated overloads as will occur on a tire that has no margin between static load and load rating. It appears then that there is no basis to assume that repeated tire overloading on curves is within the test limits of tires. The implication is that there needs to be a margin between static load and tire load rating so that the tire load stays within specs even during weight shifts on curves. This margin is absent with the factory tires on my trailer when fully loaded.
Significant and interesting admission that tire suppliers to the RV industry is just selling "round black things" which is significantly different from what happens in the automotive world (cars & pick-up trucks).
This along with the nominal 15% margin for load capacity seen on most non-RV applications could be a major contributor to the higher failure rate and much shorter life observed in RV application vs normal automotive application.
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