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Old 04-01-2019, 08:59 AM   #127
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Can someone please explain me why, when I compare the same sise ST tire, in old Goodyear list I have ,with the new Endurance list , it gives exact same loadcapacity's for the same pressure, though old list gives 65 mph as maxspeed , and Endurance 87mph.
To my opinion this can only be explained by same reference-speed used of 65mph

I wrote it in earlyer post, for P-tires also reference-speed is lower then maximum speed acording to speedcode, of tire.
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Old 04-01-2019, 09:39 AM   #128
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Here the old list I saved.
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Old 04-01-2019, 09:57 AM   #129
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Originally Posted by jadatis View Post
Can someone please explain me why, when I compare the same sise ST tire, in old Goodyear list I have ,with the new Endurance list , it gives exact same loadcapacity's for the same pressure, though old list gives 65 mph as maxspeed , and Endurance 87mph.
Sure.
Goodyear just cut and pasted a new title on an old chart.
Which tells me they don't take it seriously either.
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Old 04-01-2019, 10:54 AM   #130
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Originally Posted by jadatis View Post
Can someone please explain me why, when I compare the same sise ST tire, in old Goodyear list I have ,with the new Endurance list , it gives exact same loadcapacity's for the same pressure, though old list gives 65 mph as maxspeed , and Endurance 87mph.
To my opinion this can only be explained by same reference-speed used of 65mph

I wrote it in earlyer post, for P-tires also reference-speed is lower then maximum speed acording to speedcode, of tire.
Not sure which tire/charts your comparing; the charts for the New GY Endurance take into account the NEW construction of these tires...which have new numbers for speed, PSI, for given load...no mystery that I see. Follow the Mfg. recommendation for the specific tire instead of making this complicated...my 2 cents. I did talk with GY techs a couple times on this, by the way.
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Old 04-01-2019, 10:57 AM   #131
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Sure.
Goodyear just cut and pasted a new title on an old chart.
Which tells me they don't take it seriously either.
Or, just maybe a coincidence the data fits the new design, but higher speeds with the new construction/compounds used?? Ya think??
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Old 04-01-2019, 12:29 PM   #132
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Not sure which tire/charts your comparing; the charts for the New GY Endurance take into account the NEW construction of these tires...which have new numbers for speed, PSI, for given load...no mystery that I see. Follow the Mfg. recommendation for the specific tire instead of making this complicated...my 2 cents. I did talk with GY techs a couple times on this, by the way.

Not sure what charts you are looking at.
When I look at the old GY chart (Marathon tires) and look at the new Endurance chart and also the industry standard Load & Inflation chart, and select a size shown on all three the load capacity at specific inflation is identical.
Yes, the Endurance has sizes and Load Ranges not included in the Marathon but again I see no difference other than the change from 65 mph to 87.


As I have said before if GY and the other tire companies that all added speed ratings to their tires in 2017 has some "magic construction that gave the sudden jump in load/speed capacity then why aren't they using this stuff in their LT tires to give those tires better load capacity?
Also, how is it possible that all the importers of ST tires discovered the same magic construction?


Based on my limited examination of the Endurance tire I do believe it is probably better than the Marathon but I have serious reservations about it being as much better as an 87 mph speed rating would imply. BUT when I start reading about Endurance tires running 6 to 8 years in trailer application I will be happy to admit I am wrong.
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Old 04-01-2019, 02:02 PM   #133
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The charts are the same possibly because the load/pressure table is actually a deflection table. That is, you should get the same deflection in the tire at all of the load/pressure points shown on the load/pressure table. I do not think the materials or the construction of the tire affect actual deflection under load very much as compared to the pressure. And the chart is for the same basic design of the tire and same sizes.
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Old 04-01-2019, 02:51 PM   #134
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Reaction to last post of TM9.
My conclusion from this topic is that even the old ST D-load on most Airstreams , will last about 6 to 8 years.E ven when using a bit lower pressure, fi 55 psi, eventually in combination with not using to high speed.
This because of the comfortable reserves of tires, as exeption to the TT rule.
Hoping to collect comfirmation-reactions.
Topicstarter already gave 6 years in opening post.
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Old 04-02-2019, 07:08 AM   #135
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The charts are the same possibly because the load/pressure table is actually a deflection table. That is, you should get the same deflection in the tire at all of the load/pressure points shown on the load/pressure table. I do not think the materials or the construction of the tire affect actual deflection under load very much as compared to the pressure. And the chart is for the same basic design of the tire and same sizes.
This is so tantalizingly close that my brain actually hurts.

First, tire load tables are issued by tire standardizing organizations such as The Tire and Rim Association - the US based tire standardizing organization. (There are many other tire standardizing organizations and they consult each other in an attempt to get worldwide tire standards - they don't always succeed.)

They do NOT change over time. They are also not make/model specific. They are also not speed rating specific.

Yes, the load table is attempting to get the same deflection for each data point. In theory, that means that the tire performs the same at each data point.

But the reality is that construction DOES affect the actual deflection - it's just that the load tables are designed to be generic -a standard around which the tire is designed. Different people (manufacturers) will have different ways of designing tires to meet that standard and the result will be different constructions - although the constructions will be remarkably similar.
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Old 04-02-2019, 09:54 AM   #136
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Tireman9- "As I have said before if GY and the other tire companies that all added speed ratings to their tires in 2017 has some "magic construction that gave the sudden jump in load/speed capacity then why aren't they using this stuff in their LT tires to give those tires better load capacity?
Also, how is it possible that all the importers of ST tires discovered the same magic construction?"

How would I know; your the expert here! I would think the reason the LT tires don't have the better load capacity is they are intended for a different application and don't offer the same type sidewall construction as an ST tire; no? As we all know, (I think) the ST tires have additional lateral stress from the TT...the LT tires are originally intended for use on a "Light Truck" or "SUV"...some of us also use them on our TT's, but it's a given that the sidewalls are constructed differently then the ST tires...again, your the experts here...I just apply the info from the MFG to be safe when using their products...works for me anyway...
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Old 04-02-2019, 12:46 PM   #137
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Scaled

Scaled my trailer hitched with full gas tanks and full fresh water is 6130 lbs ready to camp not including the tongue weight


Based on GYE chart with adding a 30 % margin for load shifting flex, my trailer is near 8000 lbs that would make it 2000 LBS per tire= @ 45 PSI

And later they gave 55 psi from the tiremaker.
I calculated for the 8000 so extreme reserve of 30% for the Endurance 65 psi .

But now asuming the 6130 to be accurate determined and so fully loaded.
I trew it troug my calculator and lowered the loadindex by 6 to 111, and it adds 11% to the load. Putted the pinload on zero.Gave 56 psi as advice.
This is maximum reserve without bumping.
So you can leave your reserve-rivets at home.
Expected livetime of tires 6 years , mayby even 10 .
So 55 psi they gave is OK.


Now we cleared this, we can go offtoppic again.
The average American and sertainly if they are as clever as to buy a Airstream, understands that Tireman9 himself does not believe in the existance of special stuf to put in Trailer tires that make them carry more load.


We are writing in circels here, yust accept that maximum load is calculated or reference-speed, and this is not always the maximum speed of tire acording to speedcode.
To my conclusions the old and new ST tires have reference-speed of 65mph for wich maxload is given.


Also the old ST where allowed higher then pressure behind AT ( most 65psi) , 10psi extra was adviced for 75mph and if 85( or 87) mph speed and 10 psi extra and 10% reduction of maxload.
So in fact they had also maximum speed of 87mph ( or was it 85mph) so in any case to be compared with speedcode N.


Also for P-tires reference speed is for S to V speedcode 99mph, and maximum speed of tire is higher. So a system the tiremakers dont think strange, so can also use for other kind of tires, like the ST.


Then at last the calculation of maxload for lower then reference-pressure.
Goal for long I also accepted was that deflection had to stay the same as when maxload and reference-pressure on tire, but now I know its all to prefent overheating, I think its better to say that calculation for lower pressure is to give the tire the same heatproduction a second as when maxload and referencespeed on tire and driving the reference-speed.
Probably this is the same as when same deflection, but does not have to be.



The calculation of the pressure/loadcapacity lists should give , when putting in a graphics-line, a regular curved line.


If you would make a graphics ( if the right word for it) for the lists given for ST , you would see a verry curved line, with peacks at 50psi,65psi,and even sometimes 35 psi , all the reference-pressures of C- and D-load, and the 35 for P-tire( B-load).


This is because those lists are calculated for one loadrange , and the maximum loads of the others are glued in to it. Can be some other combinations like above a sertain pressure step over to the higher loadrange to calculate.
Ol together not a sound system to laws of mother nature.
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Old 04-03-2019, 06:37 AM   #138
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Jaditas, how did you make the correlation from the load/pressure chart to how long the tire will last?

It will last until it fails. Do you really want to go there or do you want to try to change it before failure and give up a little use?
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Old 04-03-2019, 07:15 AM   #139
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Old 04-03-2019, 08:05 AM   #140
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Jaditas, how did you make the correlation from the load/pressure chart to how long the tire will last?

It will last until it fails. Do you really want to go there or do you want to try to change it before failure and give up a little use?

"For trailer use only " Tyres in Europe have speedcode N and only 2 Loadindex steps higher then same sise and loadrange ( called Plyrating in Europe) C-tyre wich is european name for LT. That is where I got the rule of tumb 1 LI for every 10 kmph/6.3mph concluded from , so They are calculated in maxload for 140kmph/87mph and so referencespeed is maximum speed.


For Tempo 100 sticker, in Germany, so you may drive 100kmph/62mph, the tires need to be not older then 6 years.
Also some insurances insist on that not older then 6 years.
Many travel-trailers ( called caravans in Europe) have their tires more then 6 years, and pressure advice is on fora determined with my made spreadsheet often. But also in Europe the general rule of using Maximum pressure( in fact reference-pressure) is often given.
So this proves that if you give the tire a defllection that gives zero chanche on overheating , the tires last yust as long as C/LT- tires.
Michelin gives advice to let the tires be checked every year after 6 years, and in any case renew them after 10 years.


And also this topic showed already lifetime of 6 years, but still wayting for more reactions about it.
This is , so I concluded, because , even if you lower the loadindex by 6 , the tires still have a comfortable resereve .
Airstream is in this, an exeption to the rule, with tires that have comfortable reserve and giving reference-pressure of mostly 65 psi as advice.


But disatvantage of this , having to replace some rivets after every trip, pups up here.
Savety of tires so not once overheating in its livetime, is the most important. But enaugh is enaugh, and having to replace rivits should not be needed, so also important.
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