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?

[ExRocketScienti]

Tireman9 wrote:
General Request to ALL

. . . snip . . .
If you have an LT235/75R15 107/110Q Load Range D is actually a different tire than a
LT235/75R15 Load Range D.

. . . snip . . .

Didn't know that. This thread just keeps getting better and better.

[FastEagle]

ExRocketScientist wrote:

Tireman9 wrote:

ExRocketScientist wrote:


Snip

CapriRacer -- can we work up a chart?

Are you suggesting a chart that has the information in TRA book and that is already on most tire company web sites? Not sure if I understand the need. Trying to duplicate the info in all the web sites to ensure that any individual outliers are covered will be a real challenge.

I don't have access to ST type tires but maybe someone at a campground could do a quick walk around to see if they can answer this question.

Do Some, Most or All LT tires you see include the "Service Description" This is the number letter combination after the size with the number being the Load Index and the letter being the Speed Symbol.

Do Any ST tires have a Service Description?

In Passenger & LT tires the intent was to make it easy for an owner to get replacement tires as all that they should do is read the Service Description and be sure the replacement tires have a number equal or greater than the OE tire and a Speed symbol equal or faster than OE.

I think you missed what I am asking. I am not asking for the information that is on the sidewall of the LT tire. I am asking if you made an ST tire the same dimensions and inflation pressure as a particular LT tire, what would the max load rating be on its sidewall. Because of the difference in K factor, we know it is a higher number than what is on the sidewall of the LT tire. But instead of qualifying it, I am asking that it be quatified for about a dozen popular LT tire sizes.

By doing as you suggest you would be stepping HARD on he toes of the DOT.

FE

[Tireman9]

General Request to ALL

When asking about specific loads or inflation or alternate size it would really help if the basic information was provided.

While I am more than willing to consult the standards books or provide an opinion I really can't spend hours trying to first solve the problem of knowing what tire I am being asked about.

Please provide the "Complete" size. That would include the Service Description part that comes after the rim diameter as well as the type tire which is the letters up front if any.

235-r-15 isn't correct but many times that is what we get.
If you have an LT235/75R15 107/110Q Load Range D is actually a different tire than a
LT235/75R15 Load Range D.

Also concerning the load on the tires. As a minimum you should have a real scale measurement of the total load on all the tires. While you may feel you know a lot about your "Death Valley Special" RV not all of us know if it has one, two or three axles.
Ideally you should have at least once had your RV weighed with certified scales where you can get the individual loads on each tire.
Almost ALL trailers are out of balance axle to axle in addition to side to side with a good portion (usually the ones with tire problems) discovering that they are at least 5% off and sometimes as much as 15% out of balance.
So in addition to the complete tire size how about:
"I guess the 4 tires on my trailer carry 10,000 pounds"
or
"The tires on my front axle carry 5500 and the rear axle 4500"
or best of all
"RF 3300 LF 2200 LR 2700 RR 1800"

Finally if you really want to do a bang-up job then the tire Brand and design as molded on the tire, the Max load and inflation as molded on the tire and an in focus picture of the placard would be of great help.

I know that if given the choice of who to answer first I would answer the person that supplies the most information first.

OK I am now stepping off my soap box.

[Tireman9]

NHIrish wrote:
FOR THE EXPERTS;

The tires I just replaced on my Carriage Cameo were E rated DURO brand tires. The trailer has 7000 lb axles. The load rating and max psi seemed to have been overstamped at the factory from something to 3520 lbs at 85 psi.

This seems like a bogus rating to me as most E rated tires are rated at 80 psi. Could this be legit or an underhanded way to get the tire rated for 7000 lb axles?

Interesting question. We might be able to answer if you gave the complete tire size. Also a couple of pictures would help. One of the Placard and another of the "overstamped" information. Best pictures of tires are when the tire is in full sunlight.
The tire DOT would be of interest to NHTSA if there is some violation of the law.

[Chris3]

ExRocketScientist wrote:

Cox89XJ wrote:

Francesca Knowles wrote:

Cox89XJ wrote:
I’m the one that post the picture of the failed Chinese tire on page 21 of this thread. It was a Mission ST225/75R/15D rated radial tire. If cruising at 65 to 67mph is abusing, yes it was abused. It definitely was not overloaded or run low of air. When I went to a B F Goodrich Commercial TA in size LT225/75R16E rated tire, I have not had any more tire problems. Still cruising between 65 and 67mph. Out of the five tires I had to fail, they all looked like the one in the picture, but one. It’s the one that came apart just North of Birmingham. No doubt, it started the same way with tread separation. The ST’s are like a heavy duty inner tube compared to a LT tire. Mine were anyway. We usually take at least two pretty long trips every year. (400 miles one way or more) Like I’ve said on short trips the tires don’t have time to build up a lot of heat so in my Opinion, that is why some people get by with the ST’s. Short trips or not very heavy campers.

Those are Load Range C six ply tires... is it possible they were undersized to begin with for the 2003 5th wheel they came on?

What part of ST225/75R/15D do you not understand. They were "D" rated. The camper they were on when I had the tire failures was a Keystone Lerado 29BH. It weighted 8,040 Ibs. empty when on the way home after buying new. After loaded and ready to go it weighted 9300. My son works at a feed mill so weighing my rigs has never been a problem. After 5 tire failures, I knew I had to do something else. So this is what I did and I have had no more tire problems. Stay away from ST’s.

This is a good illustrative example. The OE ST tires were rated at 2540 pounds each. Using CapriRacer's 15% rule, you would want a replacement tire with a load capacity of 2988 pounds. The LT tire used as a replacement has a load rating of 2680 pounds when used in service on a light truck. If that BF Goodrich were to have the LT on the sidewall replaced with ST, the max load rating on the sidewall would also go up due to the different K factor. But we don't know what that number would be. Is it less than 2988, greater than 2988? Using the low end number CapriRacer gave earlier for the difference (9%), I calculate 2921 pounds. Pretty close. This is why having the chart would allow people to easily make informed decisions.

The one thing we do know, this particular trailer and its application did not change, only the tires changed. The previous problems with the reliability of the tires on this particular trailer have been resolved as a result.

I think you are heading off in an un-needed direction. One simply needs to look at a the placard for GAWR and choose a LT tire that meets or exceeds that number. If you are going to use ST tires that find one that is over that number by 15% and replace them every couple to three years, and hope they do not fail before then!

Chris

[ExRocketScienti]

Cox89XJ wrote:

Francesca Knowles wrote:

Cox89XJ wrote:
I’m the one that post the picture of the failed Chinese tire on page 21 of this thread. It was a Mission ST225/75R/15D rated radial tire. If cruising at 65 to 67mph is abusing, yes it was abused. It definitely was not overloaded or run low of air. When I went to a B F Goodrich Commercial TA in size LT225/75R16E rated tire, I have not had any more tire problems. Still cruising between 65 and 67mph. Out of the five tires I had to fail, they all looked like the one in the picture, but one. It’s the one that came apart just North of Birmingham. No doubt, it started the same way with tread separation. The ST’s are like a heavy duty inner tube compared to a LT tire. Mine were anyway. We usually take at least two pretty long trips every year. (400 miles one way or more) Like I’ve said on short trips the tires don’t have time to build up a lot of heat so in my Opinion, that is why some people get by with the ST’s. Short trips or not very heavy campers.

Those are Load Range C six ply tires... is it possible they were undersized to begin with for the 2003 5th wheel they came on?

What part of ST225/75R/15D do you not understand. They were "D" rated. The camper they were on when I had the tire failures was a Keystone Lerado 29BH. It weighted 8,040 Ibs. empty when on the way home after buying new. After loaded and ready to go it weighted 9300. My son works at a feed mill so weighing my rigs has never been a problem. After 5 tire failures, I knew I had to do something else. So this is what I did and I have had no more tire problems. Stay away from ST’s.

This is a good illustrative example. The OE ST tires were rated at 2540 pounds each. Using CapriRacer's 15% rule, you would want a replacement tire with a load capacity of 2988 pounds. The LT tire used as a replacement has a load rating of 2680 pounds when used in service on a light truck. If that BF Goodrich were to have the LT on the sidewall replaced with ST, the max load rating on the sidewall would also go up due to the different K factor. But we don't know what that number would be. Is it less than 2988, greater than 2988? Using the low end number CapriRacer gave earlier for the difference (9%), I calculate 2921 pounds. Pretty close. This is why having the chart would allow people to easily make informed decisions.

The one thing we do know, this particular trailer and its application did not change, only the tires changed. The previous problems with the reliability of the tires on this particular trailer have been resolved as a result.

[ExRocketScienti]

Tireman9 wrote:

ExRocketScientist wrote:


Snip

CapriRacer -- can we work up a chart?

Are you suggesting a chart that has the information in TRA book and that is already on most tire company web sites? Not sure if I understand the need. Trying to duplicate the info in all the web sites to ensure that any individual outliers are covered will be a real challenge.

I don't have access to ST type tires but maybe someone at a campground could do a quick walk around to see if they can answer this question.

Do Some, Most or All LT tires you see include the "Service Description" This is the number letter combination after the size with the number being the Load Index and the letter being the Speed Symbol.

Do Any ST tires have a Service Description?

In Passenger & LT tires the intent was to make it easy for an owner to get replacement tires as all that they should do is read the Service Description and be sure the replacement tires have a number equal or greater than the OE tire and a Speed symbol equal or faster than OE.

I think you missed what I am asking. I am not asking for the information that is on the sidewall of the LT tire. I am asking if you made an ST tire the same dimensions and inflation pressure as a particular LT tire, what would the max load rating be on its sidewall. Because of the difference in K factor, we know it is a higher number than what is on the sidewall of the LT tire. But instead of qualifying it, I am asking that it be quatified for about a dozen popular LT tire sizes.

[NHIrish]

FOR THE EXPERTS;

The tires I just replaced on my Carriage Cameo were E rated DURO brand tires. The trailer has 7000 lb axles. The load rating and max psi seemed to have been overstamped at the factory from something to 3520 lbs at 85 psi.

This seems like a bogus rating to me as most E rated tires are rated at 80 psi. Could this be legit or an underhanded way to get the tire rated for 7000 lb axles?

[CapriRacer]

Francesca Knowles wrote:
Which brings me to a question to which I'd much appreciate a concise answer:
WHEN should trailer tires be replaced?
Seems to me that visual inspection/penny tests aren't right for tires that are intermittently used...how does one know that it's time to take the plunge?

The problem is that there isn't a concise answer.

For those who have studied chemistry, there is the Arrenehius equation - a reaction rate doubles with every 10°C increase in temperature. I hope it would be understandable that a tire that spends its life in Phoenix would age much faster than one in Minneapolis.

So when these things are stated, you have to understand that it might be stated in a conservative manner - short timeframe - or on the other end.

[CapriRacer]

ExRocketScientist wrote:
No, not all of them. There couldn't be more than a dozen in 16" or smaller rims (I'm thinking this should only cover 14", 15", and 16" rims -- 5 or 6 tires in 16", 2 in 15" that I know of. I'll have to work with FastEagle on 14" -- perhaps he may be able to come up with one or two more in the 15").

Litereally, I know of only one 15", and you are right about 16" - there's only 4 sizes that I think will work, but again, they are easy to deal with.

I'm thinking that if we leave things alone, then fitting LT's to trailer service will take care of itself. There would be a built in 12% reserve - and maybe that's how to say it. That way, there isn't any confusion about what the tire says on the sidewall, vs what the chart might say.

[Cox89XJ]

ST225/75R/15D should be a D rated tire. What I have now is LT225/75R/16E and is a E rated tire. I saw the link you had and it did have it listed a C. I think it's wrong. If not "I'm totally confused"

[Francesca_Knowl]

Cox89XJ wrote:

Francesca Knowles wrote:

Cox89XJ wrote:
I’m the one that post the picture of the failed Chinese tire on page 21 of this thread. It was a Mission ST225/75R/15D rated radial tire. If cruising at 65 to 67mph is abusing, yes it was abused. It definitely was not overloaded or run low of air. When I went to a B F Goodrich Commercial TA in size LT225/75R16E rated tire, I have not had any more tire problems. Still cruising between 65 and 67mph. Out of the five tires I had to fail, they all looked like the one in the picture, but one. It’s the one that came apart just North of Birmingham. No doubt, it started the same way with tread separation. The ST’s are like a heavy duty inner tube compared to a LT tire. Mine were anyway. We usually take at least two pretty long trips every year. (400 miles one way or more) Like I’ve said on short trips the tires don’t have time to build up a lot of heat so in my Opinion, that is why some people get by with the ST’s. Short trips or not very heavy campers.

Those are Load Range C six ply tires... is it possible they were undersized to begin with for the 2003 5th wheel they came on?

What part of ST225/75R/15D do you not understand. They were "D" rated. The camper they were on when I had the tire failures was a Keystone Lerado 29BH. It weighted 8,040 Ibs. empty when on the way home after buying new. After loaded and ready to go it weighted 9300. My son works at a feed mill so weighing my rigs has never been a problem. After 5 tire failures, I knew I had to do something else. So this is what I did and I have had no more tire problems. Stay away from ST’s.

Sorry- I realized that the link I posted is NOT a Mission brand tire.

But now I'm even more confused- THAT "ST225/75R/15D" IS a c-rated tire, according to the link. Is/was that last letter on the label a load rating indicator or not????

[FastEagle]

Tireman9 wrote:


I don't have access to ST type tires but maybe someone at a campground could do a quick walk around to see if they can answer this question.

Do Some, Most or All LT tires you see include the "Service Description" This is the number letter combination after the size with the number being the Load Index and the letter being the Speed Symbol.

Do Any ST tires have a Service Description?

In Passenger & LT tires the intent was to make it easy for an owner to get replacement tires as all that they should do is read the Service Description and be sure the replacement tires have a number equal or greater than the OE tire and a Speed symbol equal or faster than OE.

ST & LT tires with the load range do not have any service conditions molded into the sidewalls. It was not approved by the 2007 rules.

FE

[Cox89XJ]

Francesca Knowles wrote:

Cox89XJ wrote:
I’m the one that post the picture of the failed Chinese tire on page 21 of this thread. It was a Mission ST225/75R/15D rated radial tire. If cruising at 65 to 67mph is abusing, yes it was abused. It definitely was not overloaded or run low of air. When I went to a B F Goodrich Commercial TA in size LT225/75R16E rated tire, I have not had any more tire problems. Still cruising between 65 and 67mph. Out of the five tires I had to fail, they all looked like the one in the picture, but one. It’s the one that came apart just North of Birmingham. No doubt, it started the same way with tread separation. The ST’s are like a heavy duty inner tube compared to a LT tire. Mine were anyway. We usually take at least two pretty long trips every year. (400 miles one way or more) Like I’ve said on short trips the tires don’t have time to build up a lot of heat so in my Opinion, that is why some people get by with the ST’s. Short trips or not very heavy campers.

Those are Load Range C six ply tires... is it possible they were undersized to begin with for the 2003 5th wheel they came on?

What part of ST225/75R/15D do you not understand. They were "D" rated. The camper they were on when I had the tire failures was a Keystone Lerado 29BH. It weighted 8,040 Ibs. empty when on the way home after buying new. After loaded and ready to go it weighted 9300. My son works at a feed mill so weighing my rigs has never been a problem. After 5 tire failures, I knew I had to do something else. So this is what I did and I have had no more tire problems. Stay away from ST’s.

[Francesca_Knowl]

Thanks for the more info about your tires!

But...those are Load Range C six ply tires... is it possible they were undersized to begin with for the 2003 5th wheel they came on?

Can you tell us what model/year 5th wheel those ST's came on?
Is it possible they were undersized to begin with?

On Edit:

Wrong tire linked to...