22.5 tire inspection. Confusing answer from dealer

Got this Private Message (PM) about sidewall "Bulges". Will keep it "private" redacting any identifying details but think there is a good learning experience for others here.

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 Thanks for sharing your knowledge, and I do like your blog!

I have 5 1/2 year old xxxxxxxxxxxx Mich XZE* tires on our coach. No cracking, and have performed well.

I found sidewall 'bumps' on two tires ("Tire store" Tire Center gent, said they're not 'bulges', as they're so slight). One maybe 3/32" of a protrusion, the other much less. The "tire store" gent said they could be belts that are misplaced or broken. But, he also said the "*" XZE's have a thicker sidewall, and that the outer layer of the tire could have separated.

I know it's hard to give advice based upon a description, but, I wanted to ask your thoughts on the opinion given to me by this "tire store" gent.

He suggested that I monitor the size of the 'bumps' daily, and if they don't grow, he felt that they were safe to drive on. When asked if he would drive on them with his family, he said from what he could see, yes. He commented that the tire was so overrated for what it was carrying weight wise on my RV, that it was not working hard.

I've always thought that once a tire starts to break down, that it was at risk for a catastrophic failure?

The tire was not unmounted for inspection, but if it was a outer layer separation as he said it could be, how would they be able to see this?

Opinion? At 5 1/2 years of age, is it worth even considering monitoring and watching for growth? Or just replace and move on?

(I have a thread on Class A, asking for ride opinions between the XZA2 and the Cont HSL1 in 315/80R size. These are the two I'm currently considering to put on the steers. But, open for input on others to consider too!)

Hope you don't mind the PM, but, I was just a bit uncertain on which way to go.

Best,
zzzzzzzzzzzzzzzz
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Here are more pictures of the feature of concern. You can see the small bulge right above the "M"

Here is my reply
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First off I do not feel that sidewall "bumps", "bulges" or "protrusions" occur because of misplaced or broken belts. Belts are under the tread not on the sidewall so I have to wonder what training, if any, the "gent" at "tire store" has received on tire construction or inspection procedures. Also not sure what he is talking about as the "outer layer" of the sidewall. In a TBR tire there is basically the thin innerliner then the body ply then the sidewall. So if he thinks the sidewall has separated then the tire has failed and should be replaced.

Now some fact based observations on sidewall bulges or outward protrusion vs depressions that are inward toward the air chamber and are indications of two completely different causes.

The inward depressions can occur once or twice around almost any radial tire. If you take a close look if full sunlight of smooth sidewall tires you will see depressions than might be about 1/4" to 1/2" wide in the circumferential direction. These are caused by the lap splice of body ply material that provides more resistance to the slight growth seen in all radials due to inflation. The depressions will run a radial direction from the wheel to the tread and seem to dispensary as you get near the tread or near the wheel. These are normal and I would only consider them minor cosmetic features of a tire.
An outward bulge may be 1/2" or as large as a couple of inches in the circumferential direction. The larger or more distinct the more concerned I would be about the durability of the tire. Usually bulges are the result of some impact damage done to the body cords that resulted in a few being broken due to shock loading.

Here is a blog post I did with pictures to help people understand.

Here is a post on an Impact Failure I had on my personal car

Now some with small features the eye plays tricks as to it being a bulge out or a depression in.  I have even seen instances of two depressions being close together such that the normal sidewall between the depressions gave the appearance of being a depression. The simple tool to use is a ruler or straight edge and to lay it across the area of interest. This will quickly identify if you have a bulge or depression.

What to do:
Review my blog posts above.
You might also find a different dealer. A simple Google for "Truck Tire Dealer Town"  where "Town" is a near-by larger community, should give you a number of options.
Are you dealing with a TCI  "Passenger/Light truck center" or a "Commercial Truck Center"  For 19.5 and larger size tires I would only deal with a Heavy truck Center.
You might also contact Michelin at their Customer Contact identifies on their RV tire page for a suggested location with people sufficiently trained in tire inspection to pass judgment on your tires.
you can tell them that your not happy with the inspection you got from "tire store" as they don't seem to understand the basics of tuck tire construction.



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Are you smarter than a tire dealer? Part 1

With apologies to the TV show "Are you smarter than a 5th grader"...

I sometimes wonder if RV owners are or at least need to be smarter than the average tire salesperson.

I bring this up based on a few recent observations and experiences. Let me give you some examples and then some suggestions to help you get the tires and service you want and need for your RV.

I have read a number of examples where RV owners had their tires inflated by a tire dealer only to later discover a variety of issues such as too much air, too little air, loose or missing valve caps or even loose valve cores. While I am sure that many dealerships want to provide good service, I think it important to remember that many times it is the "new kid" that gets the job of doing a pressure check and the on the job training may be done at your expense.
I would suggest that if you are going to have a dealer do tire inflation, it is in your best interest to provide the tire tech with clear instructions on the pressures you want. If you have more than a single inflation (fronts different than rears for example) maybe just an index card with a simple graphic along with the inflations you want will avoid confusion. You might even consider specifying a few psi higher than your real Cold Inflation Pressure or CIP so the next morning when you do your check with your Master Gauge you can let the pressure down which is always easier than needing to add a couple psi.
Also I suggest a quick walk around after the inflation check to be sure you have metal caps on all your valves. A light tightening twist may not be out of line to ensure you don't loose a cap on the way home.




Now the biggie Tire Buying.

 Next to going to the dentist, buying tires may be one of our least favorite activities in life. I do not expect to change your mind on this and turn the act of visiting a tire store something you look forward to, but I would like to offer some advice to make the task less stressful and possibly extend the time between visits so you have to go tire shopping less often.


Here is where some fact based knowledge can pay off in making the activity less stressful and might even end up saving you some money in the long term for I believe that a better purchasing decision will lead to lower probability of problems.

Lets start off by deciding if we are simply "replacing" out tires with more of the same or if we are "shopping" for tires that might deliver better performance, fewer problems or longer life.

Tire Replacement
If the tires you currently run have delivered satisfactory service, why would you think you need to make a change to a different size, type or brand? To me this would fall under the "It ain't broke, but I'm gonna try and fix it" approach. If your plan is to simply replace the tires you have with a newer set then you have it easy, simply shop for tires identical to what you already have.
When shopping I suggest you first go out and read the sidewall of your current tires. Note the Brand i.e. Goodyear, Michelin, Maxxis, Duro, Cooper etc. Next the type or design. This might be a name like "Marathon" or a number like "S637". Finally and maybe most important the COMPLETE tire size this includes the letters and numbers in front of and after the dimensional numbers and would also include the Service Description part, if any, that comes after the rim diameter. Service Description has two parts: Numbers for Load Index and a letter for the Speed Symbol or Speed Rating

For size something like "235-15" isn't correct and if that is what you tell the tire dealer, what you are really doing is sending the message that you really don't understand tires so an unscrupulous dealer may try and take advantage of you.
Technically an "LT235/75R15 107/110Q Load Range D"
is a different tire than an "LT235/75R15 Load Range D".


If you are not completely clear on this you might want to review THIS post that covers the differences for Passenger and Light Truck type tires.


Trailer or "ST" tires will have markings similar to LT type tires


Class-A Truck Bus Radials or TBR type and European commercial tires will also have size information similar to LT but with no letters in front and of course bigger numbers like "275/80R22.5 Load Range G". For TBR type tires the Service Description part is optional. If your current tires have a Service Description I would include that information when identifying the tires you want to the dealer.

You may find that shopping on the Interweb an exercise in confusion as I find many tires listed with incomplete or even incorrect tire information. Poorly designed web site may not be an indication of the competence of the dealership but it is not a good sign. This might be the first sign that you actually are smarter than the tire dealer.




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