Improper trailer brake setting

Just a quick post with the "Evidence" you might need to confirm improper brake force setting on a trailer.

This is definitely "Brake Flatspotting" from trailer tire lock-up. Higher force on relatively light loaded tires can cause this. Once there is a spot the next time you hit the brakes the tire is more likely to stop at the same spot again.

Here are some examples removed from passenger cars. ( note your ST type and LT type tires will look similar)

It might be a good idea to check your brake settings every couple thousand miles such as when you re-pack your wheel bearings.

 Did you take a close look at the tread surface when you did your last 2,000-mile tire "Free Spin" inspection or when you re-packed your wheel bearings on your trailer?

 

 

Things to do while not traveling.

Ya it's really a pain to not be able to enjoy our RVs.

But There are a couple of "Projects" that may make life a bit better down the road.

Tire Inspection

Recording your DOT Serial

Testing your TPMS

Reading to increase your general tire knowledge.

===========
First is Tire Inspection. Here we are focusing on possible separations. This is a bit easier for Trailers but also it may be more important for them because of higher separation rate. First off you need to be safe. This means ensuring the trailer or Motorhome can not move. It may be best to hook up the trailer to the TV and set the brakes. Motorhomes can use the parking brake and put the unit in gear. For either type of RV you should block the tires that are on the ground so the unit does not move.  Not everyone will be able to do these steps, but if you can, here is what I suggest.
Jack up one end of one axle (motorhomes this means one end of the front) You then want to place a reference bar or pointer or stick near the tire, then rotate the tire watching the space between the reference pointer and the tire. Do this for the side of the tread and center of the tread. If you can see the relative movement of more than 1/4" you have a suspect tire. Mark the location where the tire is moving outward. you might snap a picture where you can also read the words on the sidewall at the location of interest for future reference. You might even consider a 10 second video that shows suspect movement.  I cover the general visual inspection and have a youtube VIDEO in THIS post.  I have a series of posts with more details on tire inspection HERE.
While Trailer owners can do this for each of their tires Motorhomes are probably limited to just "spinning" the front tire and even then need a HD jack.  Remember if unsure or do not have a solid surface to work on, or the proper tools, you may not want to do this rotating inspection.

If you have a suspect location you should contact your tire dealer. If you have a video you can show them that. Since they can see the tire close up if necessary they are in the best position to confirm there is a problem or to say all is OK.

++++++++++++++++++
DOT serial. If you haven't recorded your full DOT serial numbers and kept that information with other important papers, this "downtime" might be a good opportunity when you have a nice weather day. Having this information might save you some time in the future if you hear there is a recall on your tire brand and size. Recalls are based on the DOT sericl and tires will be replaced for free if covered by a recall.

++++++++++++++++++++
Testing your TPMS.  I bet almost none of you have tested your TPMS. This should be done at least once a year. Some nice afternoon when you have nice weather with your traveling companion in the driver seat. AND when you have access to air of high enough pressure to top-off your tires. Go to each tire and unscrew the external sensor and have the person in the driver seat let you know that they can see and hear the warning for each tire position.  you don't even have to completely remove the sensor. Just unscrew enough to hear air leaking out. As soon as the monitor in the cab sounds you can screw the sensor back in to stop the air leak. Once you know that every sensor works you then need to go around and add back in the 5 psi or so that leaked out.
Doing this will also confirm you have your low pressure warning level set properly as the warning should go off as soon as you lose about 5 psi. I cover how I suggest you set your warning levels in THIS post.

+++++++++++++
Finally, with all the time on your hands, you might consider simply reading through all the posts on my RVTireSafety blog. I don't expect you to remember everything but I believe that if you have reviewed the entire blog you will then know where you can go to get an answer to just about any question you might have on tires, tire pressure, valves, TPMS, weight and inflation.


Be sure to sign up for the weekly RV Travel Newsletter, published continuously every Saturday since 2001. NOTE By subscribing to RVTravel you will get info on the newest post on RV Tire Safety too
click here.

RV Tire warranty. How do engineers "read" tire conditions?

Read the following on an RV forum
"Carlisle Tire's warranty used to state "tires must be inflated to sidewall stated pressure or warranty is void"; I don't know about now though.
How in the world do they determine if the tires are inflated to sidewall pressure? Is there a little gremlin with a report card in each tire. Some manufactures just never get out of the box.
Unless it was a bad tire, had been run flat previously, and most likely a bunch of other possibilities.  At the time of a blow out there is no way they would know other than by assumption.
Yes, most probably operator error, but only assumptions."


Sorry, but there are ways to identify the probable inflation & load history of a tire. Just as a Medical Examiner can do an autopsy and identify the signs of bad diet and poor or no exercise, or years of smoking, it is many times possible to see the physical signs of low inflation and high load.


These signs can show up in the indentation into the tire left by the wheel.

Here are examples of improper inflation or a Run Low Flex Failure of a P type, ST or LT type tire.

Melted body cord is physical proof of extreme run low 

Also, the different flex markings can be seen on the interior of a tire. In extreme cases the Innerliner (special rubber that holds air in much like a tube did in tube-type tires)

Manufacturing "Defects" will usually result in early life failure i.e. <1,000 miles.  Tire failure is in itself not proof of some nebulous "defect" even though lawyers and those not experienced in failed tire inspection want to think so.
Once you examine, in detail, a few thousand tires from both controlled testing and from day to day use & abuse the conditions seen in tires tell a story of the tire's history.
Too often people simply think of the conditions (load, speed, inflation, road) at the moment the tire fails as the "facts" to be considered when trying to decide the "why" a tire failed. In reality, the damage might have been done hours, days or even months earlier.
See THIS post on a study of pot hole damage and how long it took for some tires to fail from the impact.


As I point out in my "RV Tire Knowledge" Seminars at RV Conventions, tires are like potato salad, putting the salad back in the refrigerator after it was left for hours in the hot sun does not "fix it" and make it good to eat the next day any more than taking the burnt hot dog off the grill and letting it cool down before serving it makes for a good meal. Adding the correct air in a tire after running it low for thousands of miles, does not repair the damage. Slowing down to 50mph after hours of speeds of 70 to 80+ over the preceding weeks and months does not "fix"  or heal the thousands of microscopic cracks that were formed in the overheated and overstressed belt rubber. Once a crack is initiated it does nothing but grow. If a person stopped his smoking addiction of 2 packs a day for 40 years a couple months ago, will his lungs be clean and clear today? Not a chance.

When examining a tire, I look at the physical condition of a tire and specifically what evidence there might be. Years of experience has taught me what to look for and allows me, as a court-certified "Expert", to form an opinion that is based on the examination of many thousand tires.

##RVT933

Can TPMS provide advance warning of a Belt/Tread Separation?

Read the following on a forum for one brand of trailers where they were discussing the advantages of having a TPMS:

Someone said "How do you know if you have picked up a nail, which is leaking air, since your last walk around? A TPMS is like a fuel gauge. You could always dip your fuel tanks at every stop too."  Another reader replied "Great point; I might add, if there is something happening to the tire like tread separation which could lead to a blowout the temp likely would be going up and the alarm would sound and show temp compared to other tires.... I have read here on the Forum and other Forum's several incidents where a blown tire has caused extensive damage. Same if you picked up a nail or something where a "slow leak" might become a fast leak after your back driving on the highway... Like insurance...but, maybe not worth it to some folks."

I then replied:

As a tire engineer, I am sorry to inform you that having a belt separation will probably not generate enough heat to set the TPMS warning off.

TPMS stands for Tire Pressure Monitor System. It does not and for all intents and purposes can not provide advance warning of a tire failure due to belt/tread separation.

Air leaks can cause failures in a few miles as seen in my blog post on Blowout a real-life experience on an Airstream, to after a few hours depending on how fast the leak is. Some TPM offer warning if the pressure drops by just a couple psi in a couple of minutes or less. Some will not warn till you drop 15% to 25% below the cold inflation pressure which means you first have to lose the pressure you gained from normal driving.

I know of no consumer-level device that can advise of a belt separation as separation can take thousands of miles to grow large enough to result in the tire coming apart.

I have posted on this blog on how to do a thorough tire inspection to discover if you have a separation. Even a video and pictures of a tire belt separation before the tire came apart.  I covered the "Why" of tire failures in THIS post. Did you read and understand that information?

Do you need your own air compressor? & Certified tire inspectors

Saw an RV forum post on this topic.  Here was my answer.

If you are running a TPMS (which you, of course, should be), you should have received plenty advance notice of needing to add 3 to 5 psi. This slight loss of pressure is due to normal air loss and pressure change due to change in ambient temperature. You can easily top off your tires at your next fuel stop.


If you don't have TPMS and discover you have been driving on a tire that needs more than 20% of it's required inflation, you should be calling road service and have the tire changed, as there is a good chance you may have done permanent internal structural damage. I consider this operation on the under-inflated tire made the tire unsafe to re-inflate until the tire has had a complete internal and external inspection by a trained tire service person, not just the guy that mounts tires who probably has not received the training.

AFTER the inspection, the tire should only be inflated in an approved safety cage as doing otherwise can lead to serious personal injury.


 Regarding how to find trained, certified tire inspectors...  Use THIS link    from Tire Industry Association.


There is a directory that you can search by zip code. Those listed are TIA Members, and those with the Certified Patch next to them have been TIA Certified.

I will suggest that folks with 19.5 or larger tires or with Load Range E, F, G or higher or with any steel body ply of any Load Range go to Certified,  Commercial inspection

People with Passenger, LT or ST type tires of lower load range, can use the "Automotive" link but a certified Commercial person should be able to inspect smaller tires too.

Remember as Sgt. Esterhaus said 'Let's be careful out there'

Do you have to replace valve stems when installing TPM sensors?

Got this question on an RV forum:
"I understand from the thread that you should use metal tire stems with TPMS caps. The ends of the tire stems on our trailer are metal with the only visible rubber part right where they go through the wheel. I am guessing these are still considered rubber stems and should be replaced prior to installing TPMS?"

"Metal" stems can be a bit misleading as some newer stems may have some brass showing. I posted pictures on THIS post showing standard passenger rubber valve, a "bolt-in" metal valve, and a new style rubber/brass valve.

When it is recommended that "metal" stems be used, what is actually meant is "bolt-in". You will see the nut that retains the bolt-in stem on the outside of the wheel for most of these stems.

The concern is that over time (months or maybe years) the extra weight of TPM external sensors may cause some vibration and movement of the rubber stem body which might result is a failure of the rubber portion of the stem.

I am not aware of any testing done on the new style rubber/brass stems with a TPM sensor screwed on, so I and others are erring on the side of caution when we recommend "bolt-in" metal stems.

Cracking and failure of the rubber part of valve stems is another time & temperature aging thing, just as it is with your tires. You visually inspect your tires monthly, as outlined in your RV  owner's manual, so just include the rubber part of your valves and just as you would replace your tires when signs of significant signs or aging (cracks) are found do the same with your valves. 

You could consider running your current valves until you get new tires and at that point have the bolt in valves installed. In the meantime, I would take a close look at your stems when doing your monthly visual inspection. You can push sideways a bit on the rubber/brass stem and look for any cracks. If you find any, that would mean you need to replace them sooner rather than later.

ST tire Belt Separation "Autopsy" "How To"

This info is from an inspection I did a while ago. Some may find it informative.  A friend wrote a post on an RV Forum of his experiences and the results of my "Cut Tire Inspection". He posted:

"This summer I had a tire failure, 3 actually in all by the time I was done. If you are into the details of tire failures, this is one type of tire failure. This is a little long of a post, but there are lots of pics to go with the words and some background.
I'm not a tire expert by any means, just a machinery guy trying to figure out what went wrong with my rig so I did not repeat the same problem and could correct what went wrong. So I took this one as far as I practically could.
I caught the first failure here in my yard doing axle maintenance. When I jacked up the camper to put it on jack stands, my left rear tire would not clear the ground on the normal stand height. H’mm OK what’s up?

I looked at the left rear tire and it looked more round across the face than I remembered. I still did not know what the issue was at this point.
 


I jacked it up some more and started to take the tires off. I took all 4 tires off and I could see one tire, the left rear looked different. It was more curved across the face of the tire than the rest. Laying it on the ground it showed up more not be square to the sides.
Here is a normal one
 
After comparing the other 3 to this one rear left I measured the OD of the tire. Yup, it is 1” larger in OD circumference. OK, something let loose inside this tire.
 I put this bad tire aside, finished up the axle work, and put the spare on. I then tried to figure out what was wrong with this tire. Looking on the outside I really did not see anything much that was wrong with it other than about 180 degrees around the outside, the tire progressively was getting larger in OD up to a high spot then starting coming back down. Whatever was wrong with it created an out of round tire.
 
I demounted the tire and looked inside. Nothing really looked wrong to me inside. I happened to have a fellow RV buddy who is a retired tire engineer who has done tire failure analysis for most of his career. We hooked up and he told me how to section the tire and send it to him. So here is how we did this. He told me how to cut out the side walls. I was shocked you can cut up a side wall this easy. There is an inherent danger in doing this. Heavy gloves and a sharp knife is a must. Once you start cutting it out it sort of unzippers. You start above the tire bead and cut towards the OD, then start and cut around the circumference.
Now I had a donut. The hard part is cutting through the steel wire in the tire. Ideally, you do this on a vertical band saw with a progressive tooth blade. The rubber wants to bite and grab the blade. I did not have a large enough vertical band saw so I used a Sawzz All. Here one really has to clamp this thing down or the rubber will grab and start shaking the saw violently. You do not want any blade pinch as the rubber bites into the blade. Need to back flex it to keep it pulling apart as you cut. I clamped it to some old sawhorses and cut it apart.


Now I looked at the cross-section. Well, nothing real exciting at the 90-degree point from the high point.



 So I curled up the sample to fit in a box I could UPS to him. Here it is
I  sent him the tire and then started to investigate if I did something wrong to cause this failure. I always check tire pressure and run max cold sidewall pressure at the start of every trip. I even have my own small compressor in the truck if I need it. So under inflation was not the problem.
I also do not tow faster than 60 mph. I do not need to, big truck or not this is a safety limit for me. So I was not overrunning the 65 mph max speed rating creating excess heat.
I use white tires covers when the camper is at home. These tires are 3.5 years old at this point. I can say the first year they were only 50% covered until I have my present tire covers in place. There really was not much tire cracking. No sidewall cracks, some very fine in tread cracks and there were several stone cuts in the valleys of the treads.
Next was weight. I had not been to the scales in about 1.5 years and I added some upgrades. So I loaded the camper with stuff for a campout and full freshwater as we do haul water to some camps. I went to the scales and weighed each axle with WD engaged. I could not get each wheel position at the scales so when I came home I used my force jack to get each wheel position. Here is the weight chart.
The failed tire location has 12.5% extra tire capacity or 318# from the max load. There is some error in this data as my force jacked weighed a little heavy. It did, however, show me that the 4 tire locations are different. The front axle was pretty equal, the rear axle very different. My fresh tank sits right over the front axle which may have had something to do with the front being more even. At this point, the weight did not seem to point to a glaring problem.
Since I could not find anything wrong, yet anyway, I bought a new Maxxis tire for the spare and we headed off on vacation. My tire buddy also was on vacation so he did not yet have my tire done.
On vacation, I was 800 miles from home on the NYS Thruway and while gassing up, OMG… This tire right side rear tire does not look good. Dang, it looks like the failed one. So we pulled over in the truck lot and took it off and put the spare on. Yup, it let go too like the 1st one.


I was lucky a 2nd time I caught the failure before it let go. If you are going to have to change a tire on the road, the NYS Thruway makes a good changing spot… OK so now I have no spare…. I’m thinking of where I can get one when I get to my Mom’s house. Well…. No luck finding one close by. We did make it home OK. Another 800 miles.
When we made it home I was already working on changing tires to LT tires. When I jacked up the camper to take off the ST’s, OH boy, another one…. The tread bulged. This tire would not even roll correctly it wobbled so bad it would fall over.
So I dodged the 3rd bullet. I could not see this when it was on the camper, only when I took the weight off. The damage did not yet progress far enough yet or it was not out in the open where I could see it.
Soon my tire engineer buddy was done investigating the 1st tire I sent him. The tire failed for what is called “detachment” or what is nicknamed sometimes “slipped belts”. It is where the tread separates where the steel belts are in the tire tread from the main tire. Basically the tire unbonded itself inside the tread. Here are his analysis pictures.
He sectioned the tire sample I sent him and knowing what to look for starting to see clues of the problem. You can see small separations at the yellow arrows.
His description was “Cut 1 was my initial cut away from the identified bulge area. There are small detachments identified. If this was all that was found in the tire it would not be a serious issue.”  

Then he sectioned again and he found the entire area let go.
His description was“Cut 2 location was identified by careful measurement of tread depth and I found a location with more wear than in other areas. The large detachments between the belts on both shoulders can be seen”

 

    
  His description was “Detach 1a & 1b show the length of the detachment to be over 11" long” 
 And this one really shows the detachment separation.

His description was “Detach Width shows the width of the two detachments relative to the tread width” asked him how did this happen? His response:

Why detachment?
There are several things that can cause this. They would primarily be a breakdown of the rubber that coats the steel. This could be due to a manufacturing error or simply the selection of a lower strength rubber which cannot tolerate the forces applied to the tire. Only lab testing can determine that. Sometimes detachments can be initiated by tread cuts or punctures but that does not seem to be the case of the tire I inspected. Detachments are one of the more difficult conditions to analyze as there is a need for a lot of additional background information and data.

From this investigation, I have a perfect case to file a report with the NHTSA as I used the tires within the ratings. I have since filed 3 complaints, 1 for each tire. I’ll create a thread on how to do this filing. It is the only way we as RV’ers can help this cause of trailer tire failures become more known to the right people who can help. See here How To File a Tire Failure Complaint

There is now a growing understanding that for tandem trailer applications that a 20% more tire capacity reserve is needed to help hold up to the service of a multi-axle trailer. In my case I am towing heavy, I am not overloaded, in relation to my tire capacity. When I upgraded I targeted to get as close as I could to the 20% reserve at the heaviest loaded tire. I had a choice of load Range E in the ST or go to 16" LT and deal with tire wheel well issues. I weighed the options and went LT. See here for more on the LT change ST225/75R15 to LT225/75R16 Conversion

While LT tires may not be for everyone, knowing your weights of each tire location and where you are in relation to the tire capacity reserve is something you can do. You can also not tow over 65 mph on ST tires, keep them at max sidewall cold pressure at the start of each trip and use white tires covers over them when the camper is in storage.

I hope this helps someone in the future.
 
 

"I inspected my tires but still had a failure"

Read this on an RV trailer forum:

"Checked the air in all 4 tires and inspected them before we pulled out. We made it 20 miles from the house when the first tire let go. The tire service center and I both checked the remaining 3 and the spare. They had the correct air pressure and no signs of any issues. We made about 15 miles down the road and the second 1 blew out -- 2 roadside assistance calls and 2 insurance claims. I am not happy with dynamic tire or (RV trailer company name) at the moment."

I offered the following comment:

Sounds like the "inspections" being done are not sufficiently detailed. A "proper and complete" inspection doesn't consist of checking the outside sidewall and most of the tread for % tread wear. A LOT more is required if you want to improve your chances of finding the early signs and indications of impending tire failure.

In this blog, I have previously covered what I would consider a thorough inspection with example of what a failing tire looks like externally, and then I did an autopsy to show the actual condition of the subject tire. Note that the person making the video felt the tire had failed and cut the tire looking for the belt separation but even though he has an engineering and mechanical background, he failed to properly identify the location of the failure. IMO this was because he simply had not had enough experience in tire forensics, as you probably have to do a minimum of a few dozen autopsies before you can easily and quickly know where to do the cutting -- and that would be what is needed to find a large separation as seen in the subject tire. Smaller issues are harder to find and take a more experienced eye.

The free spin can be sufficient to establish that the subject tire is in the process of failing and should not be driven on.

Today it is popular in politics to complain about "the elite" and to disdain experience, but I believe that there are many fields where actual experience is necessary if you want competent results.

Very few tire service people have been given the opportunity to do investigative-level tire inspection, as their job normally doesn't require issuing a detailed report that identified the root cause of a tire failure. This not the tire tech's fault nor is it the fault of the tire store owner. You might liken this to the store clerk at a CVS or Walgreen pharmacy. They are simply not fully knowledgeable in the interaction of medications, which is why a Pharmacist is the person responsible to fill prescriptions, but I would not trust a Pharmacist to do surgery.

Sometimes competence only comes with experience.



Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 16th year. Learn more or subscribe.

How to avoid tire failure and RV damage. And I had a tire failure!

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.

- Next 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.

- Finally 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.

Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 14th year. Learn more or subscribe.  

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.

On to the INSPECTION


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.

NOTE Repair Guide link fixed 7/5/2019

Subscribe to the weekly RVtravel.com newsletter or one of our other newsletters about RVing. Great information and advice. Now in our 14th year. Learn more or subscribe.