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Old 10-24-2013, 09:48 AM   #29
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Originally Posted by farrel509 View Post
Status: New Wheels and Kumho LTs on the trailer now along with a set of Centramatics. Also shown is the last "blowed up" GYM. Note I have put some air in it to demonstrate how the tread separation causes a bubble under the tread. When the tire goes flat, it make it look like the tire was under-inflated, which it wasn't. All but one of my GYM failures looked like this one except the one that blew the bubble in the sidewall.
Good picture. Did you seek warranty replacement from Goodyear?
Have you filed a complaint with NHTSA?
I am curious what is the actual load on that tire and how much air do you set cold?
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Old 11-19-2013, 09:22 AM   #30
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Good picture. Did you seek warranty replacement from Goodyear? Have you filed a complaint with NHTSA? I am curious what is the actual load on that tire and how much air do you set cold?
I haven't filed any official complaints yet but I guess I should.

I had a full load in my 28' CCD (7300 GVW) but no actual weight measurement. My TPMS saved my bacon and my trailer from damage. All the tires were at the recommended 60 psi.

Funny thing is, after discovery of the first two GYM problems about 1200 miles out (bulging sidewall and tread separation) I replaced two tires with the cheapest trailer tires Big O had of the same rating. 4000 miles later these cheapie Chinese-made tires still look like new.
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Old 11-19-2013, 10:39 AM   #31
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ST Tires

I will get hammered for this but I'm gonna say it anyway.
1. File a complaint with the NHTSA.
2. ST tires with the exception of the Cooper Custom Trailer Plus are 65 MPH tires. Go to a tire with a higher speed rating (ability to withstand higher operating temperatures) any your problems will go away. Mine did.
I went to 16 inch LT tires and bgought 5 new rims. I have not had a bit of trouble since and only have to top off pressure generally once a year, in the spring.
Beginner
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Old 11-19-2013, 11:18 AM   #32
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Originally Posted by farrel509 View Post
I haven't filed any official complaints yet but I guess I should.
Asking the tire dealer to get involved with a written opinon about their observation would carry some weight if you are going to take it to the NHTSA level..

Or you could blow it all off and go camping.

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Old 11-19-2013, 11:19 AM   #33
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My 25' 85 Soverign has a plate on the left front street side that indicates 7.00 X 15 and 45 psi.D range, I think.
Right now, there are Roadkings LT on it. I inherited the AS from my aerospace engine Dad and know based on 5+ years it's time to replace them So, what manufacture would you recommend and what pressure? GVWR is 6800, axles are 3200lbs.
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Old 11-20-2013, 06:30 AM   #34
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Asking the tire dealer to get involved with a written opinon about their observation would carry some weight if you are going to take it to the NHTSA level............

I thoroughly disagree.

First, tire dealers are notoriously unreliable when it comes to analyzing tire failures - and NHTSA knows it. Don't waste your time doing this.

Second, NHTSA will use the report as a single data point regardless. They will launch an investigation based on QUANTITY, not quality. That's why it is SOOOOO important that people file a report. The investigation is the start of the process and tends to prompt tire manufacturers into doing something.
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Old 11-20-2013, 08:04 AM   #35
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I will get hammered for this but I'm gonna say it anyway. 1. File a complaint with the NHTSA. 2. ST tires with the exception of the Cooper Custom Trailer Plus are 65 MPH tires. Go to a tire with a higher speed rating (ability to withstand higher operating temperatures) any your problems will go away. Mine did. I went to 16 inch LT tires and bgought 5 new rims. I have not had a bit of trouble since and only have to top off pressure generally once a year, in the spring. Beginner
We are WAY ahead of you. Your recommendation is the purpose of this thread.
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Old 04-13-2014, 09:20 AM   #36
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Yust recently registered to this forum ,because of tire-pressure topic I wanted to react to. Been busy with that since end 2007 and gathered much info about it , but am not working in the tire busines.

I found out how the lists are made , with a formula that is different in Europe and America, though it should be the same to law of nature.
The original formula was introduced in 1928 for diagonal tires, and around 1970 adapted for radial tires in Europe and America different.
As late as 2005 America stept over for P-tires and XL only to the power used in the universal formula that Europe used since decades for all kind of radial tires.
For C-load/6PR and up America left it at the power that leads to to much deflection in the lower pressure/loadcapacity range.

Your list of ST tires can still be found at site of Goodyear, and is to my opinion verry dangerous. contacted Goodyear about it last week , but no answer yet.

Here a picture of spreadsheet I made to compare calculations.
At the bottom the list from Goodyears page and calculation 1 is power 0,585 used for diagonal tires, Yours given LT tires I calculated back to be using 0.7 power wich is standard in America for LT , Europe uses for all 0.8 power, the higher the power the lower the loadcapacity for the pressure.
Power 1 is part of reference-pressure is part of maximum load, so linear calculation, wich most think logical.
Here the picture I also sent to Goodyear with the advice to remove that ST lists for reasons so custumers cant sew them for giving dangerous information.



At the bottom a little history about the used powers.
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Old 04-14-2014, 09:26 AM   #37
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In adition to my last post.
Notice calculation 1 and the list from Goodyear at the bottom are within some rounding the same. And if you find a LT tire with same C-load and 2150 maximum load , you would notice that the loadcapacity's are within roundings the same as calculation 2 with power 0.7.

Exeption is 35 psi and this is also a pressure that belongs to a sertain tire tipe , the P-tire or sometimes called B-load so 1760 is what the maximum load should be when you had those sises ST in B-load.
they calculated for C-load and clued the D-load into it, another thing that is done wrong in American lists. For D-load a seperate list should be made, in wich lower loadcapacity for the same pressure then C-load.

Also the 60 psi bothers me with 2392 calculated and 2380 given so 12 lbs difference. But the 35 could also be because of this reason , and not for B-load reasons.
But to my conclusion these lists are first made in Kg and Kpa , wich is international standard, and then rounded down to 5 or 10 kg , then conversed for those stubern Americans that still want to keep using LBS and psi, and then again rounded to 10 lbs, wich can give these relatively large differences between the calculations and given in list.
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Old 04-14-2014, 12:19 PM   #38
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Originally Posted by LeeJ View Post
My 25' 85 Soverign has a plate on the left front street side that indicates 7.00 X 15 and 45 psi.D range, I think.
Right now, there are Roadkings LT on it. I inherited the AS from my aerospace engine Dad and know based on 5+ years it's time to replace them So, what manufacture would you recommend and what pressure? GVWR is 6800, axles are 3200lbs.
It really isn't difficult to find a new radial tire for your RV but there are a few basic steps needed.

You gave the GVWR and Axle rating but made no mention of the actual load on each tire. There are a number of posts showing that the load is seldom split evenly between axles or evenly side to side.
There are worksheets available to help you calculate the individual loads if you can't find a location with individual scales (this is difficult to do so use the worksheet). Here are 2 sites with forms you can use.
Bridgestone Commercial Truck Tires
RV Trailer Weight Calculators - Towing Capacity - Ratings


OK Lets assume you know your loads are
LF 1550 RF 1390
LR 1500 RR 1440

1550 + 15% = 1782#
You need to find a tire capable of carrying at least 1782# at its MAx pressure -10psi

The +15% is a safety factor for possibly different loading in the future
and -10 psi is to allow you to set a pressure and not need to worry about changes in ambient day to day.

Now since we are talking a multi axle trailer you need to run the max pressure in the tire all the time. This has been covered in other posts and in my tire blog but it has to do with the unique side loading for trailers.

Consult the tire Load/Inflation tables and tire specification sheets to find a tire that meets the above load & inflation capability and fits your trailer for width and OD.

One final consideration. Years ago when there were still many bias tires in the market the wheels were not always designed for radial tire loading. You should probably also either confirm your wheels are approved for radial tires or also get some new wheels.


It's not hard to do this but you do need to spend a little time doing the research correctly.

PM me if you need help
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Old 04-15-2014, 01:57 PM   #39
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Thumbs up Quick Update on Khumo LT tire setup

We towed a couple thousand miles in Feb down to the Gulf Coast with our new 16 inch wheels and tires and THERE IS A BIG DIFFERENCE in the way the trailer tows now! The combination of well balanced Khumo LT tires along with the Centramatic wheel balancer rings makes the whole rig pull smoother and quieter. Tires and wheels still look unused with no noticeable tread wear. Moving up to 16's was a DEFFINITE IMPROVEMENT in the way the trailer feels behind my big a$$ red 2500 Dodge!
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Old 11-17-2014, 10:20 PM   #40
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OK...I have read all of the very valuable information on this thread. I now know more about tire pressures than I did yesterday. We have a 2007 27FB with a dry weight of just under 5,400 lbs. Loaded is in the 6,200 lbs. range. So...is there an advantage for me to go to a 16" rim? I'm not sure I see the advantage but I am deferring to you experts.
Thank you,
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Old 11-17-2014, 10:51 PM   #41
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OK...I have read all of the very valuable information on this thread. I now know more about tire pressures than I did yesterday. We have a 2007 27FB with a dry weight of just under 5,400 lbs. Loaded is in the 6,200 lbs. range. So...is there an advantage for me to go to a 16" rim? I'm not sure I see the advantage but I am deferring to you experts.
Thank you,
Ron
Surprisingly, the biggest improvement I have see from the 16 inch tires and wheels is the added ground clearance. It surprised me how many things I use to have to watch carefully or risk scraping, that are no concern now. The biggest gain, in my opinion, however, is to get away from the goodyear marathon ST tire that have a history well documented on Airforums and other RV forums of a high failure rate. There are solutions to the GYM problems however that can be accomplished with 15 inch wheels.
The 16 inch wheel and LT tires solution is expensive, but I am very happy I did it in just the peace of mind alone.

Ken
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Old 11-18-2014, 09:09 PM   #42
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Surprisingly, the biggest improvement I have see from the 16 inch tires and wheels is the added ground clearance. It surprised me how many things I use to have to watch carefully or risk scraping, that are no concern now. The biggest gain, in my opinion, however, is to get away from the goodyear marathon ST tire that have a history well documented on Airforums and other RV forums of a high failure rate. There are solutions to the GYM problems however that can be accomplished with 15 inch wheels.
The 16 inch wheel and LT tires solution is expensive, but I am very happy I did it in just the peace of mind alone.

Ken
Ken, It would help others is you could provide some details such as actual load on the heavy end of each axle and the tire type, size and LR of the before & after change from 15" to 16" tires.
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