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Monday, June 30, 2014

RV Travel Webinar Q&A Part 1

I enjoyed this first webinar on the RV Travel YouTube channel (June 28).

Hope you found the information informative.
 The answers had to be short or I am afraid I would have put some to sleep. I do want to provide as
much info as possible so I am reviewing the comments and will provide a bit more information based on the comments

Buddy Light said "I like RV tires with more plies".
    Well Buddy you may not realize but "Ply Rating" is an old term that is based on an "equivalent strength" and not on the actual number of Ply or layers of reinforcement. You can read the material list of what is actually in your tires as it is molded on the tire sidewalls. It may say something like "Sidewall 2 Ply Polyester, Tread 2 ply Polyester + 2 ply Steel".  If you have a large RV with 22.5 wheel diameter you may be surprised to learn the sidewall of many of these tires has only one Ply of Steel in the sidewall with an additional 3 or 4 Ply of Steel in the Tread area. These tires may have a "Ply Rating" of 12 or 14 but in reality there is only 1 ply in the tire.

Astrid Bierworth said "if a truck tire is the same size as the trailer tire, could we get better service from a truck tire?"
    When I heard and answered the question I was not thinking about "Light Truck" tires as when someone says "Truck Tires" to me I immediately think of Heavy Truck tires that have wheels of 19.5" or larger. Reading your question now I think you meant to ask about using Light Truck or LT type
tires on a trailer and replace the ST or Special Trailer tires that came on the trailer originally. On my blog I started a multi-part post 6/23 "Can I change from ST to LT tires on my Trailer or 5ver?" that
addresses your question specifically. The second part will be published next week. If you subscribe to my blog you will get a notice when a new post goes up.

David Lee asked a similar question. "What's the advantage/disadvantage of using light truck tires over trailer tires?"
     Sorry David our set-up didn't allow me to see the comments live. I hope you find the answer you were looking for in my series on this topic.

AaronzDad "Roger are there any tire treatments that will add back the oils and chemicals tires need to stay flexible and extend the life of the tire?"
     No the treatments mostly remain on the surface much like Sun Tan Lotion does when you spread it on your arm. They may give the tire a "New Shine" look and may provide a little UV or Ozone protection but too often many of the treatments and their application can end up doing more damage than good. Sometimes there is "Petroleum Distillate" in the treatment and this can actually attack the tire rubber. Other times the application of the treatment removes the chemicals originally put in the
tire for protection. I suggest you limit your tire "treatment" to the same wash, sponge and soap you use on the painted surfaces of your RV or car.

Lori Singels said "The highly recommended TPMS system I bought constantly leaked. They're now a paperweight on my desk."
      I don't know who gave you the recommendation but if you bought your TPMS from a reputable dealer there should have been a warranty available that would have addressed your problem. I did a post on "What is the BEST TPMS" and in it I tried to provide the features I felt were the most important to look for in a system. Remember that just having a big advertising budget so your product name is most recognized does not mean your product is the best on the market. After some research, I bought my TPMS from TireTraker and have run them on my coach since 2012 and am very pleased.

Saturday, June 28, 2014

Quick Summary here

I have been following a number of RV forums and want to do a bit of a summary for those that don't have the time or interest to read a number of posts on this Blog: Remember more than half of the thousands of RVs that have been checked have been found to have one or more tire and/or axle in overload. So nect time you camp you can be pretty sure that one or both of the RVs parked next to you are overloading a component.

- You should have a Digital tire gauge. I have posted the results of my tests of dozens of gauges that RVrs were using and the bottom line is that about 15% were off by more than 5 psi which  IMO makes that tire gauge a good door stop or tent peg. I have provided information on how to do your own gauge "Calibration Check" to confirm the accuracy of the gauge you use daily and how to maintain your "Master Gauge"

- If you follow the advice from the two Tire Engineers on this thread you will be setting the pressure based on the appropriate method here:
     - On your TV inflate to pressure based on the Door sticker and Owner's manual for "Fully Loaded" operation. BUT get on a scale at least once to confirm you are not overloaded.
     - If you have a multi-Axle trailer you should be running the pressure on the tire sidewall. I have written in my Blog and provided the technical justification and need to follow this advice. You should still go across a scale and calculate the actual tire loads to confirm you are not overloading one or more tires
      - If you have Motorhome you need to confirm your unit's "corner weights". Use one of the worksheets I have provided links to. Use Load/Inflation chart from your tire manufacturer, to confirm you are not overloaded and identify the heavier loaded tire on each axle. Using the pressure for that load add 10% (without exceeding the wheel max) and that is your Cold set pressure for all tires on that axle.
      - If you follow the above there should be no reason to be chasing your tire inflation around unless you have a major change in Morning temperature ( More than say 30°F ) as you would only need to "Top Off" the air once a month at most.

- Don't be too anal about inflation. Variations of 1 to 3 psi day to day are normal. You should not need to make adjustments unless the Cold pressure is 4 or 5 psi away from your goal. (Multi-axle trailers might try and get no lower than 3 psi below tire sidewall pressure)

- TPMS are a WARNING device and like Insurance we should all be using them. Also just like Insurance they cannot "Prevent" bad stuff from happening but with luck they may give sufficient advance warning to lessen the impact of the bad stuff that does happen.

- If you are parked for more than a day you need to cover your tires that will be in direct sunlight with WHITE tire covers. This protects against both UV and higher temperature damage which can shorten tire life.

Monday, June 23, 2014

Can I change from ST to LT tires on my Trailer or 5ver?

This question is a real "Hot Button" on a number of RV forums and blogs. People ask this question because they want a better or alternate selection of brands or they want to improve the durability of their tires.

The answers given seem to range from "Sure, Why not" to "Absolutely Not, Never do it" and some will even offer that they think you are breaking some law if you make any change from the type, size, Load Range or cold inflation from the OE tire information shown on the tire Placard.

As we all should know by now answers about tires are never simple and straight forward and changing tires is definitely one of the more involved answers.

First off, I am not a lawyer but an Engineer and as such I form opinions based on data and facts. So here is the answer based on my 40 years experience as a Tire Design Engineer.

Yes you may be able to change tires  


 there are some things you MUST do to ensure that any change you make will actually improve your probability of having better tire durability.

My plan is to provide an outline of the steps you need to take before you make any change. I will try and include each step and each of the points of data you need to collect and evaluate. If you skip a step you may end up with a less durable tire selection which could lead to tire failure, RV damage and even an accident.

Before we start you need to consider that the most conservative approach is to make no change and to simply use the tire Construction (Bias or Radial), Type (ST or LT) and size and Load Range and inflation as specified on the placard and specification documents. This represents the RV manufacturers recommendation based on a number of assumptions as well as some legal regulations the RV MFG must follow plus in many or some cases a desire on the Mfg part to keep their costs as low as possible.

So if you still want to move forward here are the steps you need to take:
1. You need to know the actual load on each tire. This is important because A. we will be basing some decisions on the tire loading    and     B. It is possible that there is a significant unbalance in the tire loading which may be the cause of poor tire durability. With sufficient unbalance it may be impossible to provide a tire selection that would lower the probability of having problems.
To learn the actual individual tire loads you need to either find a company such as RVSEF or agency that has individual scales or to follow the steps outlined on worksheets such as This one  or This one. I have hears some people say that they have been able to get the individual tire loads from their state police or state DOT.

2. Knowing the ACTUAL LOAD on each tire you need to confirm that no single tire is loaded more than the max load molded on the tire sidewall. This is an absolute rule. If any tire is overloaded you should not move the trailer until you either change the load or change the tire.

3. Assuming no tire is overloaded we want to make sure that all tires on en axle are inflated to the same inflation. For multi-axle trailers you can lower the internal tire structural shear forces (the forces trying to tear the tire apart) by running the inflation molded on the tire sidewall. Sometimes this is stated as the Max PSI and other times it is stated as the PSI for the max load. For our purposes we will consider this the proper cold inflation you should always run. 

4. We should have "Headroom" or "Reserve Load" or "Safety Margin" on the tire loading. I suggest 15%. However I know that for many trailers 15% extra capacity above the actual load is very hard to do. Especially since some RV MFG manage to so under-size the tires that even when the trailer is empty they may not have 15% margin.

5. If you don't have at least a 10% margin I would strongly suggest you need to consider changing tires to something with more load capacity when inflated tot he sidewall PSI.

OK so you have some homework to do. We will continue this in the next post.

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Monday, June 16, 2014

Why are "Blowouts" of special concern to RV owners.

Here is a video that points out a problem unique to RVs when we are discussing what happens if a tire fails catistrophically.

and this picture shows what might happen to your electric wiring.

I have made a number of posts on Tire Failure and How to lower the chance of failure, but none of the actions you take can completely prevent a tire failure with 100% certainty.

Since RV manufacturers don't have to design or build their product to pass crash or rollover tests as cars do, I have not seen what I would consider a real effort on the part of RV MFG to place electric, fuel or propane lines behind shielding that would protect these potentially dangerous features in the event of an all too often tire failure.

So it is up to you, the RV owner, to take all the steps you reasonably can to lower and hopefully avoid the chance of tire failure so you don't have to worry about damaging these other critical components.

1. Know the actual load on each tire. Axles are seldom balanced 50/50 and it is not unusual for the heavy loaded tire to have hundreds of pounds or even a thousand pounds more load than the more lightly loaded tire.
2. Ensure you have more air pressure than needed to carry the load (I suggest a 15% margin minimum)
3. Always use an accurate digital pressure gauge when setting tire pressure
4. Use a TPMS to provide as much warning as possible of an impending tire "Blowout" due to air loss so you can slow down and stop before damage is done to the RV.
5. When inspecting your tires do not simply look at tread wear or sidewall cracking. Look for bulges and out of round conditions or locations of excessive wear that may be indications of potential tire damage that could lead to a tire failure.
6. At least once a year do or have done a "Free-Spin" inspection to help find structural problems with the tire. If you don't have a jack and the proper equipment, have this done at your tire dealer. Tell them you are looking for a separation that would show up as an "out of round or lateral run-out condition." This is much easier on trailers than Motorhomes but it seems that trailers have a higher probability of having this type of failure.

Here is an example of a trailer tire that looks OK until it is rotated. 

You can see the wheel is OK but the tire is clearly no longer round.
I had an opportunity to do an autopsy on this out of round tire and confirmed that the belts had separated. You can see the separation in this picture below, that shows the belts are no longer attached to each other.

Clearly this is a complete separation waiting to happen but just looking at the tire as it sits on the ground will not make this problem noticeable.

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Thursday, June 12, 2014

ST225/75D15 Recall Update Now two

NHTSA Campaign ID Number : 14T001

Synopsis Double Camel, in cooperation with Lionshead Specialty Tire & Wheel LLC (Lionshead), notified the agency on January 21, 2014 that they are recalling 1,440 Vail Sport ST LH 99 tubeless trailer tires, size 225/75D15, load range D, DOT code 69, manufactured from July 14, 2013, through July 27, 2013 (and a sidewall date code 2813 or 2913). On May 7, 2014, Double Camel increased the recall to include an additional 38,129 Vail Sport ST LH 99 tires encompassing build dates from November 20, 2011, through September 21, 2013 (dates codes 4711 through 3713). The total population of the tires being recalled is now 39,569. The original population of tires may fail under prolonged use and may become unseated from the rims and the additional population of tires may be more susceptible to failure due to road hazards. As such, these tires fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 119, "New Pneumatic Tires for Vehicles Other Than Passenger Cars." Tire damage from road hazards, failure from prolonged use or unseating of the tire from the rim increases the risk of a crash. Lionshead will notify owners, and dealers will replace the tires with compliant ones. The recall of the initial population of tires began in February 2014. The recall for the expanded population of tires is expected to begin in June 2014. Customers may contact Lionshead at 1-574-533-6169. 

Synopsis : Double Camel, in cooperation with Lionshead Specialty Tire & Wheel LLC (Lionshead), is recalling certain Vail Sport ST LH 99 tubeless trailer tires, size 225/75D15, manufactured from April 2012 through February 2013. The affected tires may not be marked with the load range letter designation. As such, these tires fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 119, "New Pneumatic Tires for Vehicles Other Than Passenger Cars." Tires that are missing the load range designation may cause the owner to unknowingly overload the tires, resulting in a blow out, increasing the risk of a crash. Lionshead will notify owners, and dealers will replace the tires, free of charge. The recall is expected to begin in June 2014. Owners may contact Lionshead at 1-574-533-6169.

Monday, June 9, 2014

Real Life weight calculation Question and Answer

A reader said "I have a  32' Class A MH and am about to pull the trigger on tires. I have been so concerned about making sure I get the 'right' tires, meaning, ones that have the right load range and capacity.

So just today I FINALLY found a place to weigh the MH and here's what I have:
     Actual Weight          Sticker Info
Front Axle      4,960          6,000
Rear Axle    10,660          11,000
Total            15,620          17,000

I was concerned that the 235/85R16-E 10 ply load range of 3,042 was too close to the limit so instead of I was thinking of getting a G 14 ply rated tire.

But now that I see the actual weight, should I stick with the E - 10 ply range?

Here's additional info: The RV had 3/4 tank of gas, full tank of clean water, very little in gray water and me (175 lbs)

And is this how you figure "Reserve Capacity"?

Tire rating for 235/85R16 Load Range E = 3,042       
So is the reserve load range capacity minus actual weight?       
Front Capacity           3,042 x 2       6,084
Rear Capacity            3,042 x 4      12,168
Front Axle Weight         4,960
Rear Axle Weight         10,660
Front Reserve             6,084 - 4,960       1,124 - I can add this much weight to the front
Rear Reserve            12,168 - 10,660     1,508 - and this much to the back

Compare to Hercules H-901 Load Range G = 3756 (3415 Dual..why?)
Front Capacity     3,756 x 2 = 7,512
Rear Capacity      3,415 x 4  = 13,660
Front Reserve       7,512-4,960 = 2,552 *Much better compared to 1,124 lbs
Rear Reserve        13,660-10,660 = 3,000 *Much better compared to 1,508 lbs

So, that I have actually put it all down on paper it's kind of a 'duh' moment, but here's the price difference:

6 - Cooper A/T3 - $1,159 Out the door
6 - Hercules H-901 - $1,532 OTD
Difference $373

Worth it?"

I offered the following reply
"Some comments and observations.

It helps if you use the complete tire type/size nomenclature.
I believe you have LT235/85R16 LR-E   the LT is Type. Some readers may have a trailer and have ST type tires and there are full metric tires with no leading letters. Each type has different load capabilities and ST are not intended for passenger carrying vehicles.

Second you failed to consider the correct load capacity in the dual position as your rear tires are. Tires in dual application ALWAYS have a lower rating than when in single as one of the pair is almost ALWAYS carrying more than 1/2 the load of the pair.
When you either read the tire sidewall or look at Load/Inflation charts you will see a different load capability for Single (as in your front tire) or Dual (two tires side to side as in your rear.

The load capacity for an LT235/85R16 LR-E in Dual application is probably 2,778#.  Note you should always consult the Load/Inflation tables or molded on the sidewall from the tire manufacturer of the tires you are considering as not all tires have the same load numbers. Some are slightly different for a variety of reasons.

So back to your questions.

"Reserve Capacity" would be the (max tire capability) - (the actual load) on a tire.
BUT you cannot simply assume the load on an axle is split 50/50 side to side.
Some owners find significant variation so untll you learn the individual tire loads I suggest you assume that one side is carrying 55% of the axle load.

Your heavy side Front could have 55% OF 4,960# OR 2,728#
Rear 55% of 10,660# or 5963#

Your front Reserve is 3,042#- 2,728# or 314# per tire

Your rear would be  1/2 of 5,963# or 2,982#
so the rear reserve is 2,778# - 2,982#  or a negative reserve or potential tire overload of 204# per tire.

With this information it is important that you first confirm the side to side load balance

Here is a worksheet

After confirming the real side to side split you need to re-calculate your reserve load and if needed unload or shift the load of stuff in the RV or buy the tires with more load capability BUT you should never exceed the individual axle ratings  GAWR or Vehicle rating GVWR shown on your certification label.

Finally the selection of tire brands. Do both brands offer the same warranty? Can you find dealers for both brands in the part of the country you normally travel? If you get a puncture and need a replacement tire it could end up costing more than a couple hundred dollars extra if you need a tire rush shipped in to match your current tires.

Hope this helps

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