"Dry Rot" is a misnomer regarding tires

Read this on an RV trailer forum, but most of the info applies to all types of tires.

"My understanding is that there seems to be a belief or a known orthodoxy that despite external appearances, the inside could rot out and that tires that appear all fine and dandy on the outside, after that long are not on the inside?

I believe the only "proof of concept" is common anecdotal experience:

People have owned tires that appear fine that are "old yet all seems fine", and they experience unanticipated tread separation and such....several anecdotes to the point of it being a "common wisdom" best I can tell.

Beyond that, I have not seen a "more objective" verification of this...in my mind, after the death of such an "old yet otherwise in good shape and used properly" tire, an autopsy of that tire could show evidence of this "rotting from the inside"....I am not sure anyone has posted details about what that would look like (beside unexplained otherwise tread separation)?

Absence of such "more objective review", I am very very inclined to accept the common wisdom or orthodoxy on this matter until clearly proven otherwise as the cost of being wrong is potentially massive comparatively!!!!!!!!! Many many posts on this site have expressed huge regret about pushing past such "widely accepted advice"

My response to the above:
I did "tire autopsies" for decades before retiring. I have even posted pictures on my blog and have over 30 posts that have "Failure" as a label. Best advice I can give is to read and review the information on my blog. Listen to the only two (to my knowledge) actual tire engineers on RV forums: myself and CapriRacer.

"Dry Rot" is a misnomer. Rubber is a long chain polymer. The chemistry is such that the polymeric chains break down over time. The rate the chains break is related to heat and other energy (UV) input. Nothing is actually "drying out" or "rotting" in the common understanding of the word. Sidewall cracking (dry rot) is just a symptom that suggests the internal rubber compounds have probably lost some of their elasticity, which increases the potential for cracking, which may lead to separation.

There is no single answer to why some people have longer tire life than others except for the fact that some operate their tires at higher temperatures (load, speed and inflation plus ambient temperature) than other people.

Any tire can fail with a Low Inflation sidewall flex failure or "Blowout". Radial tires in trailer application are exposed to significantly higher Interply Shear forces due to suspension design that the tires on the tow vehicle - See my post on Interply Shear.

While operating a tire can help the "Anti-Oxidants" or AO's migrate to the surface, simply driving the tire is not IMO an efficient or effective thing to do, especially when we consider that cleaning of the tire sidewall, which will remove the AO's, can result in more harm that any driving around can prevent.

How many of you have bothered to make load and inflation adjustments necessary for driving your ST type tires any faster than 65mph?

Do you even know the actual loads on your trailer tires?

How many do an annual "free spin" inspection of your trailer tires?

How many are running TPMS (tire pressure monitoring systems) so you get warned when you drop down to the minimum inflation needed to support the measured tire load?

If you feel that checking your pressure with a hand gauge is sufficient, do you make that check every 10 to 15 minutes of operation? If you have a tire leaking air you can destroy it in just a few miles, so the fact you checked the air 4 hours prior to the failure is of no importance.

Sorry for the rant but the FACTS are out there. It takes a little effort to drastically reduce the potential for premature tire failure. There is no magic snake oil spray that will make your tires last 20 years. There are steps that you can take to get 5+ years of life in trailer application and 7+ in motorhome and tow vehicle application.

##RVT798

"Only" drove 750 miles with companion dual tire low on air

Quote:

Originally Posted by Charlie What should I do? I had checked tire pressure the day before and only drove about 750 miles when the right rear inside duel blew resulting in damage to the MH and the tow. Only the side wall blew and the tire stayed on the rim. This is the first time in over 25 years of RVing that I have ever had tire trouble. I only had about 14,000 miles on these tires that are less than 2 years old. I bought the best tires they recommended. I will not say the brand but it begins with M. I had pressure set at 120 psi and they were filled when the tires were cold and had not been driven for over a month, Should I be concerned about the other tires?

Should you be concerned? It depends. Why did the tire fail? If the failure was a sidewall flex failure (sometimes called a "zipper") from running low then there was most likely an active leak, i.e. puncture or leaking valve core would be on the top of my list. In this case the other tires are no more likely to fail next week than they were last week with one exception to be covered in a moment.

If you take the failed tire to a heavy truck tire dealer for the brand involved they should be able to confirm the mode of failure.

Since you were not running a TPMS (tire pressure monitoring system), all we know is that probably sometime between checking the tire pressure and 750 miles later (2 days?) one tire had lost most/all of its air. We also know that the outer dual was run with possibly 100% overload so it probably sustained internal structural damage that shortened its life (months or years). Since we do not know how many miles at what % overload, it is impossible to predict -- so the suggested best practice is to replace the companion dual.

One thing we can do is to use this as a learning experience. With a TPMS a driver would get early warning and many times can stop before a tire is damaged and, by extension, avoid damage to the RV and even not damage the mate in a set of duals. A single warning in the life of a TPMS (years) could save much more than the cost of the system.

Now as to the other possible reason for a tire to lose air. It is possible for a piece of grit to get into the valve core and allow air to leak. I suggest you review the posts on "Valves" (list to the left) and you can see an actual example of a leaking tire and the grit that caused it. So, as I have pointed out in the past, the very act of checking air pressure can sometimes result in a leak and potentially a failed tire.

##RVT797