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Old 11-02-2010, 07:45 PM   #43
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Your weights per tire are very similar to mine X4, of course. So I would expect similar results.
I've only had my TPMS for about 1000 miles and I typically saw 71 - 72 PSI hot after a starting point of 65 on my current GYM LRDs. Check me here.....

It would seem that confirms that LREs and LRDs have similar performance characteristics relative to flexibility and tread squirm as pressure rises ( and thus temp rises) are similar at 65 PSI.

LREs will provide a cooler tire at an allowed higher pressure (indicated by a lesser percentage rise at 70 PSI)

Incidentally, I found in that Goodyear RV booklet you referred to in one of your posts shows 10 degree rise per 1.2 PSI rise. That's a little more accurate than the old SWAG at 10 degrees per 1 PSI.
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Old 11-02-2010, 09:15 PM   #44
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while collecting the pressure/temps/weight/wear data is useful,

it's important to realize the many limitations within this info.

tool accuracy/precision, point of measure and the many confounding variables.

1 psi per 10 degrees is easy to remember, 1.2 MIGHT be more precise for some tires and in some settings.

for example in late fall/winter/early spring a 10 degrees ambient temp increase may impact tire pressures LESS...

than the same change in the heat of summer.

because surface temps impact this change and cold pavement will negate some air temp increases.
_______

using the tpms to monitor tire temps has some limitations too...

stem mounted sensors are reading a different chunk of air than rim/inside temp monitors.

larger tires, inflated to HIGHER pressures have more air molecules inside and that impacts the transfer of rubber temperatures.

in other words, the mass of air molecules are a buffer/heat sink for the changing sidewall/casing/rubber temps.

tpms provide a very indirect measure of actual tire temps.

the ideal place to measure temp is WITHIN the tire (casing/belts/tread) but most of us don't have needle probes.

i am confident tire makers know what the critical internal/casing/belt temps are.

perhaps some day soon tires will have temp sensors incorporated into the carcass, it is very possible with current technology.

every tire maker warns that UNDER inflation leads to excess heat which leads2 casing/belt separaton and ultimately tire failure.

this issue SHOULD be universally known but still folks ignore or misunderstand.

this article includes thermal PIX that demonstrate the heat changes in the tire, it's a good visual for WHY under inflation is a no no...

http://www.nittotire.com/assets/safe...t%20Trucks.pdf

no doubt the same thing could be seen in UNDER inflated ST tires, with the proper tools.

ST tires have a thinner, more supple side wall than LT tires or high performance P metric tires.

with sudden air loss an ST tire is more like to fly apart (while rolling) because of the thinner sidewall.

OVER inflation is harder to determine with ST tires, we aren't riding in the stream and 'damage' from high inflation is vague and subjective.

a simple way to decide IF the trailer tires are over inflated is the 'chalk line' test...

mark a broad line of soft chalk across the entire tread width...

then roll the trailer 2-4 tire revolutions, enough to scrub off some of the chalk.

IF the tires are over inflated, the chalk pattern will demonstrate this clearly.

cheers
2air'
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Old 11-02-2010, 09:44 PM   #45
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Agreed, on the temp readings. I think that's why your temp readings above and in the link provided above reflect lower than 10 degrees per 1.2 psi. I believe you said you used an IR thermometer (I assume on the sidewall or tread). The air inside will be hotter due to airflow on the outside of the tire skin and it's cooling effect (as well as pavement temp in cool climates or in rain). I would assume that the Goodyear number of 1.2 is done with lab quality equipment inside the tire. Thus, I would prefer using the pressure rise and calculating the temp rise mathematically.

I am only interested in temp rises to set a base pressure for dramatic climatic or load changes on an occasional basis. Also, your data has helped with the decision with Ds vs. Es. as the Es will allow for greater variation of base pressures for extreme heat situations, perhaps, without sacrificing ride quality unnecessarily. I really doubt that any of the temp rises we have been examining here come anywhere close to being a carcass degrading situation. Operating consistently well outside the 10% pressure rise I could see, over time, adversely affecting case bonding. I would be willing to bet that many of these posted tire failures had been in the works for some time prior to catastrophic failure. Especially in high heat areas.

I think my IR thermometer is really only good for quickly spotting trouble at fuel stops, like hub temps, brake temps. Theoretically, TPMS abnormal pressure rises would indicate a problem, but I don't think it would catch it as early as a thermometer (ie, emerging hub problem or light brake drag)
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Old 11-02-2010, 09:59 PM   #46
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the summary info on tire temps in post #36

is from a tpms that measures air TEMPERATURE as well as pressure at the valve stems.

while i did use an IR temp gizmo for years it is no longer used on the tires...

it does still see some action on hubs, rotors, exhaust pipes and dutch ovens...



cheers
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Old 11-02-2010, 10:09 PM   #47
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Gottcha, As you stated temps are probably low at the stem also??? Is this an internal sensor or a screw on "cap"?

Never thought of the dutch oven and the IR!!!!
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Old 11-02-2010, 10:39 PM   #48
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i am using the canadian branded tpms many others here have chosen with external/screw on sensors...

tpms...

it has a really BRIGHT red led that signals major issues...

YouTube - TIRE PRESSURE MONITORING SYSTEMS, TPMS,HAWKSHEAD PRESSURE TRACK RV, TPMS

the sensors are the lightest of the external systems and the monitor displays all tire positions simultaneously.

i am tempted to toss one of the sensors INSIDE the dutch oven stuffing in a few weeks,

and compare IR surface temps to internal temps...

(hi vinny)


cheers
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Old 11-13-2011, 07:57 AM   #49
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Goodyear Marathon Tire Failure

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Originally Posted by chaimemet View Post
on our trip to NS & PEI the first day out the tread completely blew off the Marathon. Used for less than 2 years at least every 6 weeks. Changed all 4 to Carlisle Es 10 ply.
We had the left rear tire blowout on our 2008 Classic 31 yesterday. Failed tire looks exactly like the pic you posted. Tire failure did serious damage to our trailer. Did you contact Goodyear? Our trailer is going to be out of service for some time. I'll never put a set of Goodyears back on..... steve
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