A general comment on tire inspection and how it may be able to prevent RV damage due to tire failure if done properly.
There are three basic types of tire failures.
The least likely is a sudden large impact with some object in the road.
This is the least likely and is actually difficult to do. By this I
mean to have a tire that is OK with no damage having been done due to
excess heat, high load, low inflation or improper repair. It could even
be a new tire. You drive over something like a Railroad spike or into a
foot deep pot hole or over a 10" chunk of scrap steel that fell off a
truck. It has to be large and you have to hit is just right for the tire
to suffer immediate failure. I know from personal experience (doing a
special test project of tire "Rapid Air Loss") that even driving over a piece
of 2" pipe sharpened at one end and standing 2" up in the road with
sharp end up doesn't always cut through the steel belts of a tire. Yes
you might run over something that cuts the tire but you would see it in
the road and hear it hit but most of the time the air loss is not
immediate. The good news about this type of failure is that it has a
very low probability of happening. I would guess that fewer the 5% and
maybe less than 2% of RV tire failures are of this type.
is the belt separation. This is when the tire tread and belts come off
the body of the tire. This is usually the result of tire aging and long
term cumulative heat related damage that reduces the flexibility of the
rubber to the point that rather than bending the rubber develops
microscopic crack which do not heal themselves but will grow. Excess
heat and tire aging can come from many sources. Even parking in direct
sunlight with "tire protectant" spray does not lower the temperature of
the tire. Excess heat can accelerate the aging or the tire rubber
properties and drastically reduce the tire life. I would expect that if
properly diagnosed this type of failure occurs 25 to 40% of the time.
The good news is that with proper and frequent tire inspection this can
be discovered and the tire replaced before it comes apart enough to
cause damage to the RV. I did a blog post just on this topic "How do I inspect my tires"
back in Aug 12 2014. You can Google the phrase and find a number of web
pages on the topic but many simply are telling you to look at tread
depth but this is not sufficient if you want to do a complete and
competent inspection. My link included a YouTube video showing the
inspection of a tire with belt detachment that has not come apart and
the result of the "tire autopsy" I was able to perform. You can even see the separation between the belts in the above post.
there is what is commonly, and incorrectly, called a "Blowout". This is
really a failure of the tire sidewall due to excessive flexing from
running with significantly under-inflated ( probably below 50% of the
inflation needed to carry the load. For Polyester tires (mainly ST and
LT type) This heat due to flexing can be enough to reduce the strength
by half and in extreme cases even melt the cord. For Steel body tires
the bending of the steel can result in a fatigue failure similar to
bending a steel paper clip till it breaks. This type of failure may be
60 to 80% of the failures on RVs. The good news is that if you run a
TPMS you will get a warning of the air leak and hopefully you will not
ignore the warning as too many do with other warning indicators on their
dash, and take appropriate action which is to stop and pull over as
soon as safely possible. Amazingly some people, even when verbally
warned that they have a tire that is significantly under-inflated simply
choose to continue to drive off. This has happened to me a number of
times. As the saying goes "You can lead a horse to water but you can't
make them drink".
So how doe this information help you "avoid" failure and RV damage. While nothing is 100% I bet you would like to be able to prevent 90% to maybe 98% of tire failures you might experience.
To do this I suggest that you run a TPMS and to get plenty of advance warning I suggest you set the warning pressure to be the minimum needed to support the load. Then your cold inflation pressure would be about 15% higher.
Next do a "free spin" inspection with lots of light. This is relatively easy with a trailer but harder to do as your axle load increases. You may even need the HD jack from a truck tire center and the spin balance machine to get that big 295/75R22.5 tire spinning at at least 20 to 30 RPM to allow you to see if there is "wobble" similar to the video in my post on How to I Inspect my tires" above. While the tire is in the air also do a slow rotation to inspect 360° of the tire tread as well as 360° of each sidewall looking for cuts and bulges. If any are found you should get the tire to a service center for a more thorough inspection that may include de-mounting the tire.
I believe that if you don't see any bulges or wobble and don't have any localized irregular wear spots in the tread you can be reasonable confident there is no large separation.
Remember nothing is 100% but if you make an effort you can significantly improve your odds of avoiding a tire failure.
Information to show you how this can work. Three weeks ago I was doing my annual 360° inspection. My tires are 7 years old so even though I know they have always been properly inflated (4 corner weights + TPMS from 2nd week of operation), I knew I needed to be sure all was OK. I discovered one of my duals had developed stress cracking from long term parking. This was a real surprise for me but it shows that even with the best of care rubber can get old and tires do need to be replaced.
This tire was scrapped (I cut two slices from bead to tread to prevent its re-use by a "dumpster diver") as it still had lots of tread but I felt it should not be on the road.
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