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Monday, September 26, 2016

How old is too old?

Been following an RV forum thread on tire age and have been trying to explain why there is no strict guideline for exactly when a tire should be replaced. I summed up my position...

The general guidelines for motorhomes is to have the tire inspected starting at about 5 years and to replace at 10 years no matter what the inspection indicates. Due to the Interply Shear effects on belt durability, trailer tires need to be closely inspected after a couple of years and it appears that 5 years may be the max life for most applications.

I do understand that people would like a nice clear precise answer but the problem is that with load, speed and temperatures all having an impact on the life of a tire it is impossible to give a precise time of when to replace a tire.

In today's society no company can give a specific answer to the question as they would be sued if a tire failed before the "end of life" time and they would be sued if the tire lasted past the "end of life" time. We are talking about probability.

You have a sticker on your RV telling you the inflation to use based on an estimate of how much "stuff" you will be carrying. Federal Regulations say the tire load capacity at the specified inflation must be able to support the load rating of the axle. This assumes an exact 50/50 side-to-side load split all the time. It also assumes you do not put more or less load in your RV than what would result in each axle being exactly at GAWR. Many have learned of the importance of getting the actual load on each tire.

Maybe it would help if we thought about tread depth instead of age.

Exactly how much tread can be worn off before a tire becomes "unsafe'. Most states say 2/32" for passenger car tires but does that mean the tire with 3/32" tread will always perform equally to a tire with 10/32"?  Of course not. As the tread wears the wet traction capability goes down. Do you always wait till each tire gets to 2/32" before replacing it? If not, why not?

Conversely the dry traction can go up as tread depth goes down, so there is a trade-off. I dare say that if you live is an area with lots of rain or even snow, you probably change tires before they are that worn. However, if you live in the dry Southwest you may be tempted to run less than 2/32" tread as you have seldom if ever have wet traction problems.

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Thursday, August 25, 2016

Why aren't there more recalls of bad RV tires?

In addition to writing this blog, I monitor a number of different RV forums for discussions on tires and related issues. I find that many times I am suggesting to people that they should file a complaint with National Highway Traffic Safety Administration about their tire problems. Many times I get replies asking "Why Bother". While this post focuses on trailer tires the information also applies to other RV applications.

"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 NHTSA. Here is my take 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 million dollars even for a small recall. IMO sometimes a small company would simply go out of business rather than try and handle a large 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.

Here is a reply to another reader:

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 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 we see with ST tires. I do properly maintain and store my tires, even so I have had 3 failures out of 8 tires in the last three years. Anecdotally I also travel enough to see too many RV trailers on the side of the road with failures. 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 mfg 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 "Bling at low 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) IMO RV Industry lobby actively opposes any change in requirements that might increase costs by even a few dollars.
Yes ST tire life is MUCH shorter than Passenger, LT or Truck tires.

Universal use of TPMS starting in 2005 on passenger cars 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 in the 2016 world.

You could write to RVIA at but I have been told that as an industry representative organization they may not be very interested in individual complaints.

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

PS While I have done training at NHTSA in Washington DC I do not work for DOT or any Gov agency.

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