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Old 06-12-2014, 03:40 PM   #197
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Originally Posted by SteveSueMac View Post
I'm not sure how accurate this is, but my tire guy says the Michelins (P235/75/R15 LTX M/S2) are discontinued. He can't order them anymore.

Has anyone heard that from another source??
The Michelin website still has them listed. But their website has been known to be less than accurate.

I bought mine from Tire Rack.
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Old 06-13-2014, 07:31 AM   #198
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Originally Posted by SteveSueMac View Post
Ok wait - still wavering :-)

Would one advantage of LRDs over LRCs be "stiffer" sidewalls? I know the ST argument - I'm not asking from that perspective. Just pure C to D comparison of two 15" radial LT tires - does the D handle those high pressure slow turning challenges better than a C?
Thanks!
I think people make too much out of "stiffer sidewalls" between Load Ranges. There can be much more difference between different makes and models of tires of the same load Range, than there would be between different Load Ranges of the same make and model.

So I would ignore "sidewall stiffness" as a significant difference between Load Range C and Load Range D. The big difference is load carrying capacity, and that IS significant (and a by-product of using higher inflation pressure to get that increased load carrying capacity is that the higher pressure causes a stiffer sidewall - and the increased stiffness is not caused by the differences due to Load Range)
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Old 06-13-2014, 07:39 AM   #199
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Radial ST tires don't have stiff sidewalls, if you want stiff sidewalls go to a LT or bias ply tire.
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Old 06-13-2014, 08:23 AM   #200
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I agree that the high air pressure makes the whole tire stiffer. I don't think it matters on an Airstream. The Airstream has the center of gravity of a car not a square box trailer. High pressures lead to more catastrophic explosions when tires do let go. Most car tires let go when they are run at very low pressures because of a leak. ST tires seem to blow at pressure from poor construction. If you look at the weight of an ST tire compared to a car tire. The car tire is heavier construction. If you need more load capacity then go to the 16" LT rated tire.

Perry


Quote:
Originally Posted by CapriRacer View Post
I think people make too much out of "stiffer sidewalls" between Load Ranges. There can be much more difference between different makes and models of tires of the same load Range, than there would be between different Load Ranges of the same make and model.

So I would ignore "sidewall stiffness" as a significant difference between Load Range C and Load Range D. The big difference is load carrying capacity, and that IS significant (and a by-product of using higher inflation pressure to get that increased load carrying capacity is that the higher pressure causes a stiffer sidewall - and the increased stiffness is not caused by the differences due to Load Range)
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Old 06-14-2014, 12:45 AM   #201
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Originally Posted by SteveSueMac View Post
I'm not sure how accurate this is, but my tire guy says the Michelins (P235/75/R15 LTX M/S2) are discontinued. He can't order them anymore.

Has anyone heard that from another source??
235/75R15 36210 Michelin LTX M/S 2
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Old 06-14-2014, 08:15 AM   #202
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Ok, apparently the guy I talked with by phone was new :-). As it happens, they had 2 of these Michelins on the rack. They are now going on my trailer

Got here and before going forward with the G26es I asked if we could line them up to see the size difference. It's really about 1.5" in overall height compared to the Michelins. It wouldn't be as drastic compared to the GYMs but the Michelins are wider and taller than the GYMs.

When these wear out, I will take a look at the options available at that time. The G26es are intriguing but I'd definitely have to adjust my hitch so I'll ride this out until then. It's possible these are/will be discontinued and by that point, my only option might be 16" wheels and tires. We'll see then.

Thanks for all the great insights and suggestions! See you on the road!
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Old 06-14-2014, 08:28 AM   #203
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Originally Posted by SteveSueMac View Post
Ok wait - still wavering :-)

Would one advantage of LRDs over LRCs be "stiffer" sidewalls? I know the ST argument - I'm not asking from that perspective. Just pure C to D comparison of two 15" radial LT tires - does the D handle those high pressure slow turning challenges better than a C?
Thanks!
Tire sidewall "stiffness" much like the "Load Capacity" is a function of the tire inflation. many times a LR-C and LR-D have identical sidewall construction and components so at the same inflation the sidewalls are equally "stiff".

I know for a FACT the sidewall material on my LT225/85R16 LR-E is identical to a LT225/85R16 LR-D based on a review of the tire build specification. The difference is in the bead wire so the LR-E can meed a specific high inflation test.

Since the bead wire does not bend of flex the sidewall "stiffness" of the two different Load Range tires would be identical at the same inflation.
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Old 06-14-2014, 08:37 AM   #204
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I think maybe Capri Racer or Tireman9 could give you the best answer on that question, Steve.
Tire weight is something to look at or compare (when all else is the same). LT235/75/15

The Pirelli Scorpion ATR LRD tire weighs 38lbs
The GoodYear Wrangler HT LRC weighs 32lbs

However-
The Firestone Transforce AT LRC weighs 44lbs I think this may be because this tire has a "Commercial" designation.

Most of the weight difference is in the tread unless you are comparing a Polyester body tire with a Steel body tire. Many "Commercial" tires have steel body ply much like 22.5 dia "truck tires" seen on Class-A coaches.

Tire weight can be misleading and I do not consider it a good "yardstick" when selecting tires.
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Old 06-14-2014, 08:41 AM   #205
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I think the difference is that load range C tires max out at 50 psi. Load range D goes to 65. You get more weight capacity with the D's. The extra psi probably makes them stiffer, good for turning, etc. If the trailer came with load range D then that is what I would want to go with. If it came with steel wheels and load range C tires then I would use a load range C or a p 235 XL tire at 50 psi. Mine works fine with those. I did not want to put the C tires or the P 235XL tires on a trailer that came with Al wheels and load range d tires at 65 psi. The big trailer sets still most of the timea so I am using GYMs on it still. Going on 4 years and time to change if I decide I want to pull it.

Comment on the wheels is good. If changing to a higher inflation level you should ALWAYS confirm that you are not exceeding the wheel max inflation rating. The wheel may have sticker or number stamped on it. Many aluminum wheels have both load and inflation max cast on back side of a spoke. The wheel manufacturer should be able to provide the ratings. Your RV MFG may or may not be able to answer the question.
I feel they should know this info but that is expecting competence on the part of the person you are talking with. Some have it some don't.

First thing to confirm are the numbers on your tire Placard.
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Old 06-14-2014, 09:12 AM   #206
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I agree that the high air pressure makes the whole tire stiffer. I don't think it matters on an Airstream. The Airstream has the center of gravity of a car not a square box trailer. High pressures lead to more catastrophic explosions when tires do let go. Most car tires let go when they are run at very low pressures because of a leak. ST tires seem to blow at pressure from poor construction. If you look at the weight of an ST tire compared to a car tire. The car tire is heavier construction. If you need more load capacity then go to the 16" LT rated tire.

Perry
In my 40 years as a tire engineer I have only seen a handful of tires fail due to high inflation and those tires had been inflated to 2-1/2 times the sidewall max and none of those were ST type tires. Most is not all "Blowouts" are in fact Run Low Sidewall Flex Failures.

Here is a video of just such a failure on an Airstream. After seeing the video I tried unsuccessfully to contact the owners but on July 22 2012 I posted on my blog my analysis "Blowout" A Real Life Experience
of what I saw and feel I have established the real cause of the failure was a loss of air pressure.

If interested you can Google the post title to see the analysis.
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Old 06-15-2014, 12:05 PM   #207
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Here's the link. Very interesting analysis. Of course the question unanswered based on the analysis is why this tire lost pressure...

http://www.rvtiresafety.com/2012/07/...real-life.html

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Old 06-15-2014, 06:21 PM   #208
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Here's the link. Very interesting analysis. Of course the question unanswered based on the analysis is why this tire lost pressure...

www.rvtiresafety.com/2012/07/run-low-flex-failure-real-life.html

Jack
If I may, perhaps I can explain why you can't always find the offending loss of pressure location.

There is a failure condition commonly referred to as a "Run Flat" - that is, the tire was operated with little or no inflation pressure. Roger accurately described the evidence that leads to that diagnosis.

When I was examining failed tires, I would sometimes get all the pieces - and about 90% of the time, I could find the puncture site. Sometimes it wasn't obvious, but sometimes was obvious - and, surprisingly, even obvious ones were sometimes overlooked by whoever first examined the tire and reported the tire as having a defect - although the defect was neither named (Yes, they do have specific names), nor its location.

So you may ask about the other 10%.

Rex Grogan - a tire engineer formerly of Dunlop - has published a number of books on diagnosing tire failures and in his book entitled "An Investigator's Guide to Tire Failures", he has a chart showing the puncture sites of tires based on a survey he made of tires from the West Mercia (UK) Police Department - and 13% of the punctures occurred in the area that is damaged during when a tire is run flat.

My analysis of tires with similar conditions is right in line with his findings. In fact, I have rarely (as in less than 1% of the time) found a problem from the tire itself that caused this condition.

So it should not be a surprise not to find the puncture site when pieces are missing.
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Old 06-15-2014, 07:29 PM   #209
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The Marathons and maybe other ST tires suffer from tread separation and I would assume that the tread ruptures at some point and then the pressure is lost. I do agree that most car tires fail from poor maintenance or a nail that goes un noticed and leads to pressure loss. I think that many of the ST failures that happen here are a result of the tire actually failing. I see people driving around with 10 psi or less in their tires and I know that they are in for a flat. If you try to get their attention you usually get dirty looks. I have personally never had a tire blow out. I have had flats and found potential flats before they blew out from low pressure. If you come out of a store and you see your trailer or car leaning to one side, don't get in and drive it.

Perry

Quote:
Originally Posted by Tireman9 View Post
In my 40 years as a tire engineer I have only seen a handful of tires fail due to high inflation and those tires had been inflated to 2-1/2 times the sidewall max and none of those were ST type tires. Most is not all "Blowouts" are in fact Run Low Sidewall Flex Failures.

Here is a video of just such a failure on an Airstream. After seeing the video I tried unsuccessfully to contact the owners but on July 22 2012 I posted on my blog my analysis "Blowout" A Real Life Experience
of what I saw and feel I have established the real cause of the failure was a loss of air pressure.

If interested you can Google the post title to see the analysis.
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Old 06-15-2014, 07:38 PM   #210
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Maybe part of getting your license is proving that you can change a tire on the vehicle you drove in on and showing you can also check air pressure and check basic fluid levels and going through a preflight of the vehicle before getting in it. I wonder how come the dude in the video could not change his own tire. It is not like they were 80 or something. It does not sound like his failure was from low pressure.

Perry
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