Revived Trailer Tire Thread (formerly on the 5th Wheel Forum

[CapriRacer]

OK, I'll try this again but with a different tack.

I am of the opinion that ST tires should have a 15% reserve capacity (85% of the load at a given pressure) in order to be reasonably sure they won't fail. There are a couple of ways of estimating what the actual load is on a given tire of a trailer, but the best way is to actually measure each tire. The RMA has a procedure to follow:

http://www.rma.org/publications/tire_service_professionals/index.cfm?PublicationID=11516

I am of the opinion that this 15% reserve capacity is likely to require higher load ranges and larger sized ST tires - or both. And maybe even a step into LT type tires - and here is where it gets tricky.

While I feel uncomfortable recommending that LT tires be loaded to their maximum load, that is in essence the result. I feel uncomfortable with that because I don't have enough experience to say it with confidence. However, I have no hesitation in recommending replacing ST tires with LT tires if it can be done with enough clearances around the tire.

A couple of other points:

ST tires can be inflated 10 psi over the maximum pressure listed in the sidewall of the tire - and I'd recommend that if you can't get to a 15% reserve capacity.

Recent bulletins from the tire industry indicate that tires degrade simply due to time. The age of a tire is important even if the tire is unused.

There is some disagreement over how to best express this age limitation,
but my take is:

If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years. If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years. States in between are ..... ah ........ in between.

A rule of thumb for estimating if you need more load carrying capacity:

Check the cold (ambient temperature) tire pressure before starting off. Measure the inflation pressure after an hour of driving.

If the tire pressure build up is less than 10%, it's OK. If the pressure build up is between 10% and 15%, then continue to monitor until you are sure it is not above 15%. If the pressure buildup is 15% or greater, add load carrying capacity (and one of the ways to do that is to add pressure). For ST and LT tires, NEVER use more than 10 psi over the sidewall pressure.

Any questions?

[Chris3]

Fasteagle I highly doubt that Michelin does a separate production run of XPS RIBs for those installed OEM on RV's. Have you actually seen one without speed rating codes? Chris

[FastEagle]

Ok, here is one for the engineers. Just how much credence do you put on a tires speed restrictions? The individual tire manufacturers are the ones that self impose speed limits for their RV trailer tires or others used on other recreation vehicles.

I hate to bring brand names into a discussion but it’s necessary here to show where such information might be found.

Click here, on the Carlisle tire page click on the resources tab and then open the PDF; Trailer tire maintenance. In the PDF file you will find that Carlisle is very careful about how they word the speed limit of 60 MPH for towing trailers. When filing claims against Carlisle trailer tires I would also be very careful not to admit constantly operating my trailer over 60 MPH.

Carlisle is a major provider of trailer tires to many users in the RV trailer industry and just as many if not more users outside of the RV trailer industry. They can provide ST tires from 12” to 16” and their LRF 16” tire is rated for 3960# @ 95 psi making it very suitable for the 7000# axles.



Here I’m going to talk about a specific tire. It’s talked about a lot on the internet tire threads but is yet to be tested as an Original Equipment tire. I bring this particular tire up because it has a double standard speed rating. It’s the Michelin XPS Rib. If a buyer goes down to their local Michelin retailer and purchases some XPS Ribs as replacements for some ST tires they will most likely get XPS Rib tires with a “Q” (99 MPH) speed symbol molded into the tire. When that same tire is used as OE on a RV the symbol is omitted and the specs in the RV usage section of the Michelin document will list the speed rating for that use as 75 MPH. Because the tire is not used as OE in the RV trailer industry it’s a toss-up as to it’s speed restriction on those axles. Can you shed some light on that?

XPS highway tire specs


XPS RV tire specs



FastEagle

[JIMNLIN]

Many years before the net we had several made in the USA branded ST tire manufactures such as Firestone/BFG/Goodyear/Cooper/Carlisle and other I've forgotten. I never heard of derating a tire pressure on a trailer with a minimum pressure number till I came on this website in '03.

Anyhow Goodyear says; weighing your RV

"Special ConsiderationsUnless trying to resolve poor ride quality problems with an RV trailer, it is recommended that trailer tires be inflated to the pressure indicated on the sidewall of the tire. Trailer tires experience significant lateral (side-to-side) loads due to vehicle sway from uneven roads or passing vehicles. Using the inflation pressure engraved on the sidewall will provide optimum load carrying capacity and minimize heat build-up."

and Carlisle has several websites with about the same info;http://www.carlisletire.com/product_care/articles/trailer_tire_safety_031505.pdf

(snip)
"However; trailer weight does not fluctuate sig-nificantly with variances in fresh and waste water and supplies, and trailer owners should always inflate to the maximum pressure listed on the tire sidewall. (snip)

and another Carlisle website tire care info http://www.carlisletire.com/product_care/trailer_tire_poster.pdf.

[Tireman9]

anoldman wrote:
Unfortunately, my camper came with 14" wheels and LT tires for it are scarce to none. I thought about buying new 15" wheels, but that is yet another expense on a limited budget. I just ordered 4 new Maxxis tires with a higher load rating. Hopefully that will give me better durability.

I, like so many other owners, am very frustrated by the shoddy quality tires available for our campers. The realization that severe damage can be caused by these overloaded and inferior tires is my biggest worry on the road. Before leaving and at every stop I diligently inspect my tires for damage. In comparison, I seldom glance at my truck tires because of my confidence in them.

Whether a company has repair facilities or not should not prohibit or excuse them from standing behind their products. It has nothing to do with tire construction or statistics and everything to do with good business principles. I wonder how many tires Maxxis has sold based on the glowing reviews from sites like this and how many sales others, like Greenball, have lost as well. Perhaps our actions will cause them to improve their products and when that happens we'll start praising them as well. That is the power of forums like this and how we all gain from our collective experiences.

While it may be true that some sales are lost or gained based on forum posts the real question of sub-standard tires is not being addressed with a forum posting. There are minimum quality standards all tires must meet if they are to be sold in the US. These standards are backed by laws and significant penalties. However if people that experience tire failures simply complain to their neighbor nothing will happen to get bad tires removed or replaced. This post provides information and links on how and where to repost safety related issues.

Now to your specific concern as to what size tires to get. It would be helpful if you could provide
1. The original tire size including load range.
2. The placard minimum inflation recommendation from the RV mfg.
3. The actual individual tire loads.
With the answers to those three questions the engineers with tire experience following this thread could provide some information that may be of help. We don't need to start a guessing game and we do need all three questions answered if we are going to be able to help.

[Chris3]

CarpriRacer, can you address the question about 17.5 rims and tires for larger 5th wheels and when the 16" run out of capacity? For many larger 5th wheels there is not a 16" tire that allows for much reserve capacity. GAWRings in the 6750 to 7K range seem to be in never never land with many on OEM wheels only rated to 80 pounds inflation.

Chris

[CapriRacer]

FastEagle wrote:

CapriRacer wrote:

FastEagle wrote:
....A manufacturer of ST tires says their tires are to be aired to the maximum sidewall pressure at all times. They say they are designed to be aired that way. They are so sure about it that it's a warranty requirement.

FE

Can we get a link?

Page seven.

Page Seven

Thanks for the link. Interesting phraseology.

[FastEagle]

CapriRacer wrote:

FastEagle wrote:
....A manufacturer of ST tires says their tires are to be aired to the maximum sidewall pressure at all times. They say they are designed to be aired that way. They are so sure about it that it's a warranty requirement.

FE

Can we get a link?

Page seven.

Page Seven

[anoldman]

Unfortunately, my camper came with 14" wheels and LT tires for it are scarce to none. I thought about buying new 15" wheels, but that is yet another expense on a limited budget. I just ordered 4 new Maxxis tires with a higher load rating. Hopefully that will give me better durability.

I, like so many other owners, am very frustrated by the shoddy quality tires available for our campers. The realization that severe damage can be caused by these overloaded and inferior tires is my biggest worry on the road. Before leaving and at every stop I diligently inspect my tires for damage. In comparison, I seldom glance at my truck tires because of my confidence in them.

Whether a company has repair facilities or not should not prohibit or excuse them from standing behind their products. It has nothing to do with tire construction or statistics and everything to do with good business principles. I wonder how many tires Maxxis has sold based on the glowing reviews from sites like this and how many sales others, like Greenball, have lost as well. Perhaps our actions will cause them to improve their products and when that happens we'll start praising them as well. That is the power of forums like this and how we all gain from our collective experiences.

[Chris3]

anoldman wrote:

azjeffh wrote:
Just received word that Greenball denied my claim due to the cause was impact related (i.e. pot hole). So, I guess their tires are not produced to travel on roads. Funny thing is, I've never hit a "significant" pot hole. Oh well, what are you gonna do?

For the poster that feels good switching to Maxxis E rated tires, I wish you better luck than me. Mine had sidewall separation after 26 months (lost 2 at the same time). Not over weight, under inflated, etc. As a matter of fact, Discount Tire replaced all of them under the mfgr's warranty.

Never had a China BOMB until these Tow Master POS tires. At least when the Maxxis' went they didn't take out the fender skirt.

Gonna try Commercial TA's next. Just crossing my fingers.

I sure am glad I ran across your post. The junk tires on my camper need replacing and I was looking at Tow Master tires as a replacement. I believe all brands fail at one time or another, but a company that won't stand behind its product is a deal killer for sure. Thanks again for sharing.

There is not much difference between any of the bunch of 35 pounders (Marathon, Duro, Tow Max, Mission, Tow Master, Load Star etc etc). The only ST remaining on the market that is different from the others is the Maxxis (those manufactured in Thailand). They however are not as good as most LT's if you can find one that meets your weight requirement. The Marathon at least has a company that will repair your rv and has B/M stores across the country.

If you read this thread carefully and learn about the K factor, then you can decide if you want to use a tire that is loaded to that extent!

Chris

[anoldman]

azjeffh wrote:
Just received word that Greenball denied my claim due to the cause was impact related (i.e. pot hole). So, I guess their tires are not produced to travel on roads. Funny thing is, I've never hit a "significant" pot hole. Oh well, what are you gonna do?

For the poster that feels good switching to Maxxis E rated tires, I wish you better luck than me. Mine had sidewall separation after 26 months (lost 2 at the same time). Not over weight, under inflated, etc. As a matter of fact, Discount Tire replaced all of them under the mfgr's warranty.

Never had a China BOMB until these Tow Master POS tires. At least when the Maxxis' went they didn't take out the fender skirt.

Gonna try Commercial TA's next. Just crossing my fingers.

I sure am glad I ran across your post. The junk tires on my camper need replacing and I was looking at Tow Master tires as a replacement. I believe all brands fail at one time or another, but a company that won't stand behind its product is a deal killer for sure. Thanks again for sharing.

[just_me]

CapriRacer wrote:

FastEagle wrote:
....A manufacturer of ST tires says their tires are to be aired to the maximum sidewall pressure at all times. They say they are designed to be aired that way. They are so sure about it that it's a warranty requirement. How can a tire like that be compared to another ST tire who's manufacturer allows air pressure manipulations?
FE

Can we get a link?

I think the only link we have is the tag on the side of the trailer that states info on the trailer and tires (Original) and @PSI required for the weight of the unit. On mine it had "D" rated tires 235/80/16, Bulges developed on the side walls when I called for adjustment, @ about 5K they said the manufacture did not use the right tire load rating and it should have been a "E" and would not stand behind an adjustment. Dealer stepped up and took care of me. Does everyone run there Lt's @ 80psi when not loaded? I don't.

[CapriRacer]

FastEagle wrote:
....A manufacturer of ST tires says their tires are to be aired to the maximum sidewall pressure at all times. They say they are designed to be aired that way. They are so sure about it that it's a warranty requirement. How can a tire like that be compared to another ST tire who's manufacturer allows air pressure manipulations?
FE

Can we get a link?

[Howaboutnow]

Tireman9 wrote:

Chris wrote:
Capriracer, you talked about we consumers banding together to share info on what works! We have been trying to do that here for a good number of years! However tire threads often get closed when posters show up with a stack of documents and start saying "you can not do that"! And some flat do not like the brand/model that works better than any other. That leads to more back and forth that gets threads closed. SAD!

In reading your posts over the last week it does not seem to be as black and white as they claim!

So keep the info flowing.

Thanks - Chris

Chris IMO the main reason that there might be sub standard tires on the highway and why there may be some RVs made with undersized tires is that few if any RV owners complain to the proper sources about the quality of our products. I cover the needed actions in my post on why "bad" tires are on the road. BUT given the fact that the RV community accepts quality in the RV industry that is more like what we got from "Detroit" in the 60's we only have ourselves to blane.

This is the bottom line. We are getting only what we accept.

[Tireman9]

CapriRacer wrote:

Tireman9 wrote:
A tire is considered to be "flat" if it has less than 80% of the minimum recommended inflation.

Doesn't make any difference what type tire we are talking about P, LT, ST or TB (TB is Truck Bus or what you see on Class-A MH)

Roger, Good to hear from you.

Was on vacation so I joined this party late. Reading fast as I can tryin to catch up.

[ExRocketScienti]

Tireman9 wrote:

ExRocketScientist wrote:
. . . snip . . .

. . . snip . . .
This is why trailer tires need to run the max sidewall inflation all the time. Increased inflation will decrease the slip angle needed to generate the cornering force so increasing the inflation will also decrease the shear internal to the tire at the interface between the belt edges and should also decrease the tendancy to peal the belts off the carcass.

This is another excellent piece of information from this thread, given the number of people who have peeled their tread right off. More new information brought to the table.