1967 Axle and Tire Replacement Recommendation

[CapriRacer]

Originally Posted by Inland RV Center, In

Your thought's on updating old wheels from "C" that was used for many years, to "D" rating tires, or "E" ratings.

I was told many times that the wheel will split.

Dozens of times, that has been reported to me over the years.

Some say impossible.

Andy

I don't see the failure mechanism.

If the load on the wheel is the same, why would the wheel fail?

But if we talk about using a Load Range E tires in place of a Load Range C - AND - inflating the LR E to 80 psi (instead of the LR C's 50 psi), that I could believe.

- BUT -

A Load Range E inflated to 50 psi has the same load carrying capacity as a Load Range C does at 50 psi. I don't think the minor differences in tire construction is enough to be the difference between wheels failing and not.

And lastly, I have been trying to find wheel engineers to ask this question: If the load on the wheel is the same, if more inflation pressure is used, how significant is the increase in stress on the wheel?

I originally suspected that the difference is small as if this were important, wheels would be routinely marked with a maximum inflation pressure - but they aren't.

I did stumble on a wheel designer once (not quite an engineer) and he said that the load was the only thing they considered. That's not quite enough confirmation for my taste, so I am continuing my quest.

And lastly, I can absolutely believe that people have taken a wheel designed for a Load Range C and put it where a Load Range D or E tire is needed - and the wheel failed - and here's the tricky part: They would report this as the difference in Load Range, not the difference in load.

[TG Twinkie]

I think the wheel failure (if any) may be caused by the higher air pressures that some inflate the tires to when using "D" and "E" rated tires on rims designed for "C" rated tires. Plus installing tires that are meant for a wider rim.
I believe the rims on my Argosy are original. They are stamped with a load rating of 2,600 pounds at 65 psi MAX.
I think if I were to install "E" rated tires on these rims and inflate them to the 80 psi max. There would be an increase in the wheel failure risk.
I run "D" rated tires at 55#. So far 10,000 miles and no problems. I limit my speed to 60 mph.

[Action]

I have a similar question and slightly different.

If the load capacity is "X" is with standard steel wheel and "C" rated tire inflated to max stamped on tire. What advantage is accomplisted by changing to a "D" or "E" rated tire and inflating to less than max ? (and still acceptable for the rim.)

From what was stated above there is no greater capacity in load based on lower inflation rate of "D" or "E" rated tire. And may be the answer is more complex than I state the question just not sure.

>>>Action

[DKB_SATX]

Originally Posted by Action

I have a similar question and slightly different.

If the load capacity is "X" is with standard steel wheel and "C" rated tire inflated to max stamped on tire. What advantage is accomplisted by changing to a "D" or "E" rated tire and inflating to less than max ? (and still acceptable for the rim.)

From what was stated above there is no greater capacity in load based on lower inflation rate of "D" or "E" rated tire. And may be the answer is more complex than I state the question just not sure.

>>>Action

Ready availability of replacement tires. My '75 Argosy came to me with LRC tires, 3 of which match my rated gross weight for the trailer so they were sufficient. No one seemed to stock the C tires, even though Carlisle said they manufacture them.

My solution was to go the Michelin LTX route, but if you want to stick with STs it might be necessary to move to a D or E to get the tires easily from your local tire dealer.

[Action]

I can relate as the tire world is not static.

On a much different vehicle (1974 E -100 that was special ordered - go figure) I had a 14" rim with a factory equipped "E" rated tires. When it came time to replace the factory tires I request the stock set up. "E" rated tires in a 14" rim were very rare. I was much more ignorant of tires and rating that I am now. Based on future load (there really wasn't any) and cost I elected to move farther down the alphabet rating scale.

>>>>>>Action

[Inland RV Center, In]

Originally Posted by CapriRacer

I originally suspected that the difference is small as if this were important, wheels would be routinely marked with a maximum inflation pressure - but they aren't.

Quality wheels always have either a label with the maximum air pressure on them, or the wheel is stamped.

Andy

[CapriRacer]

Originally Posted by Inland RV Center, In

Quality wheels always have either a label with the maximum air pressure on them, or the wheel is stamped.

Andy

2 thoughts:

Next to my office is a room chock full of wheels - and most of them are OE wheels - and I don't think there is a one that has max pressure stamped on the wheel.

If max pressure were so important, wouldn't that be stamped on the wheel, and not on a label that can be removed - regardless of quality?

[Wazbro]

Originally Posted by Action

I have a similar question and slightly different.

If the load capacity is "X" is with standard steel wheel and "C" rated tire inflated to max stamped on tire. What advantage is accomplisted by changing to a "D" or "E" rated tire and inflating to less than max ? (and still acceptable for the rim.)

From what was stated above there is no greater capacity in load based on lower inflation rate of "D" or "E" rated tire. And may be the answer is more complex than I state the question just not sure.

>>>Action

Well 1 reason is that it has been reported that tires lose as much as 30% of their strength in 5 years so a D or E tire inflated to the pressure of a C would still have the capacity of a new C rated tire after 5 years.

[Inland RV Center, In]

Originally Posted by CapriRacer

2 thoughts:

Next to my office is a room chock full of wheels - and most of them are OE wheels - and I don't think there is a one that has max pressure stamped on the wheel.

If max pressure were so important, wouldn't that be stamped on the wheel, and not on a label that can be removed - regardless of quality?

I have no idea since I am not into manufacturing wheels.

Safety is always my concerns.

I, personally, would have "ZERO" faith in any wheel not properly marked. Therefore, I will not provide such a wheel to customers that trust us.

Andy

[Action]

Originally Posted by Wazbro

Well 1 reason is that it has been reported that tires lose as much as 30% of their strength in 5 years so a D or E tire inflated to the pressure of a C would still have the capacity of a new C rated tire after 5 years.

That is interesting, I have never heard of this. And in my opinon, after being mounted for 5 years the service life of any tire is approaching the end no matter what tread is left.

My daily driver's get about 13 to 15,000 miles a year in usage. At the end of 5 years that is 75,000 miles. Yikes. Currently because of my life's events, I have a trailer* that has brand new tires in July of 2009 with may be 4000 miles of useage. (And that is being generous) I suspect these tires will be shot in another couple of years due to age. This trailer will get used this year as my life's events have changed again to free up some time. At least this is the plan. I live in Phoenix where sun is a big factor. Those tires have always been covered to block out UV. No cracks when last checked.

With that stated I have this from RMA https://www.rma.org/RMA%20Tire%20Ser...cationID=11453

And from Tire Rack Tire Tech Information - Tire Aging – Part #1 While there is not a published US standard for end of tire service life based on age however Tire Rack concludes that 6 to 10 years is the limit. See the bottom of that article.

If a tire loses 30% of it's strength (or almost a third) in my opinon that tire is no longer suited for the load it was designed to handle. Or it is beyond it's service life! I would strongly question that thought process. And if that is correct, does one inflate an "E" rated tire to max less the 30% loss to get a "C" rated capacity after 5 years of usage?

*That dual axle 28' trailer supports about 7300 pounds of load. The tires (14" rim) have a maxload rating of 1880. So my max load capacity for the tires is 7520 #s. Razor thin margin in my opinion.

>>>>>>>>>>>>>>>Action

[CapriRacer]

Originally Posted by Action

I have a similar question and slightly different.

If the load capacity is "X" is with standard steel wheel and "C" rated tire inflated to max stamped on tire. What advantage is accomplisted by changing to a "D" or "E" rated tire and inflating to less than max ? (and still acceptable for the rim.)

From what was stated above there is no greater capacity in load based on lower inflation rate of "D" or "E" rated tire. And may be the answer is more complex than I state the question just not sure.

>>>Action

I think the advantage is that you are starting with a tire of greater potential, and not using that potential. This has to do with "Fatigue" - which I will explain in the next post.

[CapriRacer]

Originally Posted by Wazbro

Well 1 reason is that it has been reported that tires lose as much as 30% of their strength in 5 years.......

I have a problem with the way this is stated. No, I don't have a problem with Wazbro - or whoever extracted this. I have a problem with whoever originallt stated it that way. Here's why:

"Fatigue". Here's a Wikipedia article about it:

http://en.wikipedia.org/wiki/Fatigue_(material)

About 1/3 down the page is an S-N curve (Stress vs Number of cycles). S-N curves look very similar regardless of the material in question.

What the S-N curve says - among many things - is that the number of cycles to failure is a function of the stress level. So something with a lower stress level will have more cycles before it fails - like using a Load Range D in place of a Load Range C.

The S-N curve also says that you can estimate the remaining cycles to failure. - And I think that is what the statement in question is trying to express. Unfortunately, it is stated in such an easy to understand way that it becomes inaccurate and confusing.

Please note, that fatigue occurs in everything produced. It's just that tires have a pretty well defined "life".

I should also point out that the S-N curve does NOT account for the deteriortion caused by the environment - oxygen, ozone, UV rays, etc. So even unused tires become unusable after a length of time (depending on the environment)

[Wazbro]

Originally Posted by CapriRacer

I have a problem with the way this is stated. No, I don't have a problem with Wazbro - or whoever extracted this. I have a problem with whoever originallt stated it that way. Here's why:

"Fatigue". Here's a Wikipedia article about it:

http://en.wikipedia.org/wiki/Fatigue_(material)

About 1/3 down the page is an S-N curve (Stress vs Number of cycles). S-N curves look very similar regardless of the material in question.

What the S-N curve says - among many things - is that the number of cycles to failure is a function of the stress level. So something with a lower stress level will have more cycles before it fails - like using a Load Range D in place of a Load Range C.

The S-N curve also says that you can estimate the remaining cycles to failure. - And I think that is what the statement in question is trying to express. Unfortunately, it is stated in such an easy to understand way that it becomes inaccurate and confusing.

Please note, that fatigue occurs in everything produced. It's just that tires have a pretty well defined "life".

I should also point out that the S-N curve does NOT account for the deteriortion caused by the environment - oxygen, ozone, UV rays, etc. So even unused tires become unusable after a length of time (depending on the environment)

Thank you for the way you stated that.

I saw this listed a couple of places, of coarse now I can't find it. I repeated the statement to show having reserve strength would add to safety. I believe you are probably right that it was oversimplified.

IMHO way to often information seems to be dumbed down for the media and then they dumb it down more or only report the part they understand and/or agree with, sometimes past the point of making the information useless to making it misleading.

[Lance M]

Originally Posted by Inland RV Center, In

Quality wheels always have either a label with the maximum air pressure on them, or the wheel is stamped.

Andy

Originally Posted by CapriRacer

2 thoughts:

Next to my office is a room chock full of wheels - and most of them are OE wheels - and I don't think there is a one that has max pressure stamped on the wheel.

If max pressure were so important, wouldn't that be stamped on the wheel, and not on a label that can be removed - regardless of quality?

I have seen wheels (old) with a max pressure stamped on them. Usually it is on the back side of the rim somewhere a normal owner would never see it. I don't know what the rim manufacturers association rules are on this, but it seems that labeling requirements may have changed. I think an inquiry to DEXSTAR would enlighten us all.

I have replaced a few wheels lately. The picture below is a new steel wheel from DEXSTAR, made in the USA. I think most people would find this to be a quality wheel. The only markings it has are on a label on the rim next to the valve stem. No mention of a maximum pressure anywhere.

The label is very clear about the load and proper torque application to the lug nuts.
This made in China wheel is on a 2007 25' International OB.

This rim has a LR-E tire on it. Seems like a lot to me for a trailer with a #7,000 GAWR.

[Action]

TOP, that wheel is not steel either.

For a stamped steel wheel they have come in 2 flavors since split rims. Rivited and welded. Older style the center was rivited and most recent wheels the center is welded.
Assume max trailer load of 7400 #s, if a rim was designed for a certain load capacity, let's say 2600 #'s per wheel. And the end user has load range "C" tires (6 ply rating) installed that has a load capacity of less than 1900 #'s at max inflation 50 psi. If the end user were to upgrade to a load range "D" (8 ply rating) with a max load capacity of just shy of 2400# at max pressure of 65 psi is there an issue?

(Tires now have a load index from 71 to 110 so in the above example moving from a load index 102 = 1874# to aload index 110 = 2337#)


>>>>>Action

[Lance M]

I'm sorry I didn't mean to confuse anyone. The second pic is an aluminum rim from a 2007 25' International. The first pic is a pic of the sticker on a new welded center STEEL wheel. Here is a pic of the whole shebang.



No. No issue at all.

I just wanted to point out that not all wheels have a "Max Pressure" stamp or tag on them.