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Tuesday, August 12, 2014

How do I inspect my tires?

Got an email the other day asking about inspecting tires. This blog and many others will tell you that you should do a thorough inspection annually and doing the inspection becomes more important as times goes on.

The problem is, few know even the basics of proper tire inspection. For some it's only looking at the tread to be sure there is some tread pattern available. Others will bend at the waist and look at one sidewall to inspect for large cracks.

Well, sorry to say that doing a proper tire inspection is a lot more involved. You will need to get down on the ground, you will get your hands dirty and you will need a good bright work light. A dim, old style flash light doesn't provide either enough light or uniform lighting to allow a good visual examination. So lets start with the tools you will need. I suggest a rug or old blanket so you can lay down and even scoot part way under your RV to see the back side of the tire. For lighting a work light with at least 75 watt rating. As a low cost alternative if you don't already have a work light is the inexpensive LED light similar to THIS one or even THIS one. Note the low costs for these lights. A pair of thin gloves. You need to be able to feel bumps and bulges on the tire so thick leather work gloves like these

 will not do.I know that many have disposable thin, Latex or Nitrile gloves they use when handling their holding tank hose and that type or similar will work fine to help keeping your hands cleaner as tires are very dirty and rubbing your fingers across the sidewall will transfer oils, waxes, dust and dirt to your fingers.
Finally don't forget safety glasses. Dirt can drop from under the RV onto your face or when you are removing objects from the tread they can pop out and hit you.

We need to be consistent and thorough in our inspection as we need to cover 100% of both sidewalls and 100% of the tread. This also means that after you have inspected all your tires you will need to move the RV a couple of feet so the portion of the tread that was on the ground can be seen. Depending on your RV, there may also be areas on the inside sidewall where the tire is too close to the frame or other component which prevents a clear view of that part of the tire and this may require a couple of small moves. When going under your RV be sure the engine is off, the transmission is in Park and you have blocked the wheels from moving either direction.

The following applies to all tires. If you have a towable there are some extra steps you NEED to do and we will cover them later.


1. Tread. You are looking for nails, screws and other items lodged in the tire. Sometimes you will find rocks wedged in parts of the tread pattern. It doesn't hurt to remove them using a screwdriver as sometimes stones can "drill" into a tire causing damage. I would not use a knife or other sharp tool. If you find a nail or screw in the tread, it is possible that the object goes all they way into the air chamber and if removed may cause an air loss. If for example you find a screw you might start to remove it but if you get more than 1/4 to 1/2" loose and the screw is still in the tire I would screw it back in and seek service as you don't want to lose air by completely removing the screw if you are not a a location where your tire can be easily be changed. Making this decision takes some thought to avoid making the problem worse.
While looking at the tread see if the pattern looks uniformly worn both across the tread and around the tire. Non-uniform wear may be a sign of an alignment issue and in some cases are an early sign of a structural problem internal to the tire like THIS,

or it may not be serious and is just cosmetic.

If you see some localized wear and want it looked at by a tire dealer it helps if you make a notation using the letters and numbers on the sidewall for reference. An example might be "Local wear on Right Front, inside shoulder of tread, starting at number 3 clockwise to letter G".  Giving a dealer this guidance will do two things. One it will save them time in locating the area of concern and two it will let them know you have done a thorough job of inspecting tires so they are less likely to ignore you and more likely to treat you as a knowledgeable customer that knows something about tires. This is a lot better than telling the dealer "The tread on the front tire looks strange".
While we are still looking at the tread we also want to note for more detailed inspection  any cuts that are deeper than 1/16" in the grooves.

2. Sidewalls:  This applies to both inner and outer sidewall. First do a general inspection for cuts or punctures. Punctures in the edge of the tread and down to the wheel should NOT BE REPAIRED. Some people may claim to have done a satisfactory sidewall repair but there is just too much flexing for a repair to last. There are published GUIDES that show the only location (in the tread) where a repair is acceptable. This applies to ALL BRANDS of tires.  Any cut where the body cord is visible means the tire is scrap and should not be used. Next we want to find bulges. You want to feel for bumps and bulges using your fingertips and gently slide around the complete surface of both sidewalls of the tire. If the frame prevents this then you need to identify where you could not feel the sidewall so you can finish that part of the sidewall after moving the RV. Bulges can be a sign of broken body cord. I recently did a POST on broken body cord on one of my personal tires.
Depressions however are probably OK as for tires with multiple ply such as most LT and ST type tires this is just a small overlap where extra material is located. if in question just note the location as mentioned above
and ask a dealer to confirm.

Trailers: Tires on towables seem to have a much shorter life than tires on motorized RVs like Class-A, B or C. Part of the reason for this is the unique and higher structural loading placed on these tires during any turning. The sharper the turn the higher the stress is on the tire ply. This loading is working to tear the tire apart. These forces can lead to separations which ultimately can lead to tread and belts being thrown off the
carcass and in extreme cases a rapid loss of air when the belt separates. TPMS will not provide warning of a tread separation so the only tool available to RV owners is a thorough visual inspection.

The good news is that many times these separations can be discovered by doing a "free spin" inspection as
seen in THIS video. At the beginning you see that the wheel is round and shows no side to side movement. Then we see the tire as it wobbles side to side and even is out of round. This tire has failed and must be replaced at once. Here you can see when I did an "autopsy"

we discovered the belts are almost completely separated on this tire. To do a "free spin" you must get the tire up in the air so it rotates freely. Thus can be done with a jack or even one of the ramps that will raise one side of the trailer high enough as seen in THIS video. This is just one example.
As you can see there is some work involved but doing a thorough inspection may prevent serious problems later on down the road. You will also find that after doing a few tires you will become more knowledgeable about this important safety item on your RV. your tires.

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Thursday, July 31, 2014

Are my tires too old?

 How old is too old ?  The guy may have a lot of "life experience" and be older than the normal rider, but can you say with certainty he is too old to be riding a bike?

After reading my posts on the benefit of using white tire covers, a reader noted my comment on having tires that were 7 years old on my coach. He thought I was not practicing good preventive maintenance as he had heard that all RV tires should be replaced by 6 years "no matter what".

I offered that the recommendation on the max age of a tire on an RV is not as clear cut as some would believe.

According to this RV tire guide from Michelin they recommend annual tire inspection by a qualified tire dealer after 5 years but replace at 10.

I have seen posts such as this on RV forums " The Michelin RV Tire Guide specifically says  that  tires may be good for  up to 10 years, but  recommends that they should be thoroughly inspected annually, especially after five years.  This same information is summarized in the Michelin TSB on Service Life for RV Tires:
The Michelin Truck & RV Tire Warranty is for the life of the original tread, not a fixed number of years, and starts on the purchase date .Sidewall date is used only if you have no sales invoice.
Note, however, that passenger and light truck tires may have different parameters. If your motorhome uses 16" tires, I would apply the passenger & light truck recommendations.
That said, I will continue to replace my tires at the seven year mark. Far too much risk of a blow out beyond that point.  The risk of body damage or accident is just too great for me

Now I have not been able to confirm every statement about tire life that people post on different forums. The above examples are from Michelin and are about tires on cars, trucks and motorhomes. There are those that say for RV trailer application 3 to 5 years is a maximum.

Here is a good editorial from a trade publication on the topic

Clearly there is no simple answer. As a tire engineer I can tell you that there are just too many variables that would need to be considered before a simple xx months max type answer can be provided.

Some variables would include time spent exposed to direct sunlight, time spent at temperatures above 80F, 100F,  120F, 140F or above. How much reserve load capacity (Load capability minus actual load)  for each tire. Amount of time spent at or below the minimum inflation needed to carry the actual tire load.

My tires have been in service since April 2008. I run 15 psi above what is needed for the actual individual tire load and the tires have never been lower than 8psi above the minimum inflation needed. The tires are always covered if I am parked for more than a day. I have not traveled where the temperature exceeded ever exceeded 90F. By training and experience I am a Forensic Tire Inspection Specialist so am fully qualified to do internal and external tire inspections.

I will be replacing my two front tires next Spring and two additional tires each year there after.  BUT this does not mean you should not be replacing your tires when they are less than 10 or 8 or even 5 years as the "life experience" of your tires is different.

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WATCH A VIDEO: How your RV tires can "age out" before they wear out.

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