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Old 08-16-2016, 10:16 PM   #61
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Letís look at some statistics. Iím not going to name the trailer or its manufacturer. I assure you, these are true figures.

I have chosen a popular model from an also popular manufacturer. Itís a dual axle 33 foot travel trailer. GVWR is 7690# with a 690# published hitch weight. Once that is deducted from the GVWR and the remainder divided by two we find the axles to be 3500# GAWR ea.. Fitted to each end of those axles are ST205/75R14C tires with a recommended tire inflation value of 50 PSI ea.. Those tires at maximum inflation pressures provide 1760# of load capacity ea.. Not much room for error. Letís assume the tires have a speed rating of 65 MPH. That means that at 65 MPH on this trailer fully loaded they are completely maxed-out. They are going to rapidly degrade and fail, very early, when used as described.

This particular model has the ability to carry 43 gal of fresh water and 90 gal of waste water. For an owner leaving a dry camp and forgetting to dump the waste water they could then be traveling with more than 700# of water in the trailerĎs tanks. Thatís nearly half of the trailerís full cargo capacity of 1545#. In a hurry to get home and unload, kick it up to 70 MPH. POP goes a ďChinaĒ tire.

You will not find tire statistics like that on any automotive vehicle. If in doubt, do some math with the figures on your car's tire placard.
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Old 08-16-2016, 11:23 PM   #62
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Originally Posted by crookedread View Post
I assume that the #1,000 overload is based on a static measurement. I have always wondered what that weight would be in one of the sharp corners on the way to the coast! Just guessing that could be 2 or 3 thousand over in that situation.


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Vehicle dynamics calculations suggest that large RV (trailers and MH) can see +500# loading on outside of turn tires above the static measurements. This is one reason MH have better tire life is because they start out with larger margin than trailers due to the selection of tires by the MFG and the fundamental design of tires with ST tires being designed to meet 1970 standards while LT and Class-A RV tires are made to 2002 standards or newer.
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Old 08-16-2016, 11:39 PM   #63
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Originally Posted by palmetto rogue View Post
Tireman this seems to me to be a big picture economics issue. Is it true that the auto and truck industry does not experience the failure rate or short life that the ST tires experience? If true then the RV tire industry and rv chassis mfgs apparently are not willing to manufacture to the same expectations of the auto industry leading to all the woes that we experience. Look in any parking lot and many of the cars made before 2007 when tp monitors were required are running on poorly inflated tires. My guess is that these do not fail at the same rate as ST tires. I also have an engineering/QA background and have abused tires for 50 years in racing, towing and with heavy Ag equipment and never seen the failure issues with ST tires. I do properly maintain and store my tires and have had two ST sets fail (2 tires on 1 and 1 tire on the second) in 3 years. Anecdotally I also travel enough to see too many rv trailers on the side of the road with blowouts. If not for economics why would ST tires only be made to be rated at 65 mph when we live in a faster world? I try to stay under this for fuel economy but find myself at higher speeds frequently. Impossible to practically operate within rated limits. Is this whole issue because rv mfgs do not want to pass on the cost of safe tires? I understand Motorhome tire life is 5 to 7 years and tractor trailer operators get hundreds of thousands of miles on tires. ST tires 2 years? Please explain.
IMO the main reason RV TT mfg do not provide better tire fitment (load capacity) is they sell based on more Bling at a lower cost. When shopping the RV market you will almost never meet a salesperson who tries to sell based on specifications. Yes tires applied to TT are designed to meet 1970 driving speeds (55 mph speed limit) RV Industry lobby actively opposes any change in requirements that might increase costs by even $5.
Yes ST tire life is MUCH shorter than Passenger, LT or Truck tires.

Universal use of TPMS starting in 2005 has significantly lowered tire failure rates on cars but RVIA (mfg association) does not support TPMS as OE on RVs is one example. They also do not support applying 2002 DOT test requirements on ST type tires so you are stuck with 1970 performance.

Article in current issue of RVTravel in Editor's corner: Nobody in the RV industry is looking out for RVers regarding the quality of RVs and the availability of campgrounds. We've heard plenty from unhappy RVers; now hear why you're not top priority with the industry. "
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Old 08-17-2016, 12:06 AM   #64
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I get tired of hearing that most ST tire problems are caused by the RV owner. I simply don't believe it based on my own experience. NHTSA; never heard of them, much less knew I could file a complaint. So I asked my tire dealer. She said that they do turn in reports on tire problems themselves and/or turn the tires over to their tire reps for analysis. That went for tires they sold or other brands they replaced. So I don't believe the argument that NHTSA doesn't have enough data to see a trend for ST China bombs. Doesn't make sense if tire dealers are turning in info to them to protect their sales and customers.
Scott I have a number of posts on National Highway Traffic Safety Administration. Here is my latest on recalls and filing complaints.

They have a limited budget so must focus on most important first. That means things that can result in death or personal injury. TT only see financial loss so obviously would come last.
While your dealer may have sent information to the tire importer I have noted that many times the volume of tires in a "family" may be low enough to avoid the requirement for data be sent to NHTSA.

in 2014 207 Million passenger tires were sold, 29 Mil LT 18 Mil Truck or 254 Mil tires sold each year where a failure might result in personal injury

According to RVIA data there are 9 Mil RVs on the road but this includes approx 1.1 mil motorhomes so if we have 7.9 mil trailers with say 90% on ST type tires buying a set of 4 tires once every 4 years we are looking at maybe 7 mil St type tires sold each year

So if you were NHTSA where would you spend your research tax dollars? On the quality of 254 Mil tires where there might be injury or on the quality of 7 mil tires with almost no chance of injury?

There have been a few recalls on ST type tires but I am also aware of times when ST tires are not recalled simply because the records are poor as most are imports. In some cases the importer is a small company so does not have the money to do a recall that can cost many Mil of dollars even for a small recall.

The RV owners seldom file complaints and many times when they do they do not include the DOT serial so that complaint can not be used in the tally of number of complaints.

If you want to learn more read some of my 14 posts about NHTSA.

PS While I have delivered training at NHTSA in Washington DC I do not work for DOT or any Gov agency.
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Old 08-17-2016, 12:11 AM   #65
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Followup. I bought my 5th wheel to have fun and travel - not to have to research or report tire failure analysis or root cause or replacement equivalents or provide maintenance exceeding that of a 24/7 manufacturing plant. This whole tire and axle business should be engineered into a rolling system that is a non issue and requires little maintenance. Too many of it's customers are seniors that do not want to or know how to mess with this.

You are correct. Have you complained to your RV dealer & MFG?

The reason I write my blog is to try and provide facts on why tires fail and what owners can do to lower the potential for tire problems. My biggest problem is that many seem to feel that having driven on maybe 40 to 100 tires over their lifetime they know more than someone that has been involved with maybe 25,000 tire autopsies.
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Old 08-17-2016, 07:57 AM   #66
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Immediately after buying the second set of tires (marabombs) after 2 blow outs with the first set of 1= year old tires and damage to both sides of the trailer, I pulled into the Indiana Cedar Creek factory for parts. After viewing the damage the response by the very polite service manager stated "this is the responsibility of the tire manufacturer". Root cause analysis conclusion --chinese ST tires - no practical followup action possible. This is why we seek solutions such as LT tires. After this and now comments on this forum about loading, it should be illegal to install 6000lb axles, wheels and tires on any fifth wheel. The limits of the system will be exceeded if only at one wheel location.
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Old 08-17-2016, 08:01 AM   #67
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I should have illegal to install any 2 axle 6000 lb system.
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Old 08-17-2016, 08:25 AM   #68
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Originally Posted by palmetto rogue View Post
Immediately after buying the second set of tires (marabombs) after 2 blow outs with the first set of 1= year old tires and damage to both sides of the trailer, I pulled into the Indiana Cedar Creek factory for parts. After viewing the damage the response by the very polite service manager stated "this is the responsibility of the tire manufacturer". Root cause analysis conclusion --chinese ST tires - no practical followup action possible. This is why we seek solutions such as LT tires. After this and now comments on this forum about loading, it should be illegal to install 6000lb axles, wheels and tires on any fifth wheel. The limits of the system will be exceeded if only at one wheel location.
But did you have a TPMS installed in order to help prevent "the bomb"?
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Old 08-17-2016, 08:25 AM   #69
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last time. I apologize to all as this subject has been a sore spot with me. After writing the above my wife handed me the newest Trailer Life magazine in which is an article about Maxis tires. The article makes the case for not buying "chinese ST tires" as opposed to Maxis asian tires. Hope they get it right - still have a 65 mph limit though rated at 80 mph.
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Old 08-17-2016, 09:22 AM   #70
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Yes on the TPMS. Not fast enough on the first set of tires but did catch the failure on the marabombs.
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