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Old 02-14-2016, 06:42 PM   #11
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Don't go over the sidewall max.

2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K


2011 Flagstaff 831FKBSS
2010 F250 4X4 5.4L 3.73 LS
EQUALIZER E4 1200/12000
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Old 02-15-2016, 03:26 AM   #12
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Originally Posted by Happy Vibe View Post
Are you sure it is 10 psi over the max or is it the vehicle manufacture says inflate to 40 the max is 55 so you can go up the 10 psi without going over the sidewall max.
Yes I am shure , see at bottom of first given page ( page 40) of this document of Goodyear.
An older document to my recollection gave even 20 psi extra for Comercial truck tires , but in this newer one they also give 10 psi for them, both fatt printed.

And ofcource the note , not ot go over the rimm given maximum pressure.
I see that as cold pressure , so warm it is allowed higher,
My idea then is that its better to be save for the tires with that 10 psi extra , and if rimm says 50 psi , I would take the risk of going over that.
Best ofcource would be to take rimms wich can handle higher pressure , but only once read a Dutch topic about rimms that went leaking, to my conclusion by the to high pressure . In this case original personscar tires on caravan and where chanched to D-load tires with AT-pressure of 65 psi.
Probably rimms where max 50 psi ( AT pressure of normal car tires in Europe is 36 psi, USA 35 psi) .

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Old 02-15-2016, 05:30 AM   #13
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That is for LT tires not ST tires. And the interpretation of maximum load I believe is calculated by the vehicle manufacture not the max the tire can handle. I will stick with max on the side of the tire and unless you are a tire expert I would not be telling people to exceed the max on the side wall.

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Old 02-15-2016, 07:30 AM   #14
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Searched for RV tires with list of ST tires too, but came to a newer version of it here.
But it did not give the info I wanted anymore.
In the older version they did allow that 10 psi more for ST tires and even prescribed it for when maximum speed of 75 m/h instead of 65 m/h ( for wich maxload table was given.
For max even higher maxspeed they prescribed and 10 psi more and 10% reduction of maximum load.

Will mail them to ask why .
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Old 02-17-2016, 06:35 AM   #15
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Interested in response.
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Old 02-17-2016, 08:06 AM   #16
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Will give the answer here, if I get any, because Goodyear is not happy with me , because a few years ago , I pointed them on the ST tire list all radial tires, that are calculated with the formula for diagonal tires ,wich lead to higher loadcapacity in the lower pressure then that for radial tires used in Europe and since 2006 ( after Ford Firestone affaire was forgotten) also USA TRA has taken over .
Sended them a mail directly after my last message here , but no reaction yet.
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Old 02-22-2016, 01:19 PM   #17
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Mailed Goodyear but only got little wiser by their answers.
Will copy the conversation .

My first mail:

In an older version of this pdf on your site,
I mean to remember there was a prescription of to use 10 psi higher
pressure then given for the maximum load ( AT-pressure ,
maxloadpressure, reference-pressure) when maximum speed is 75m/h instead of the 65m/h
the maximum load is given for on sidewall. Even an advice for and 10 psi extra and 10% maxloadreduction when maxspeed 85m/h.
A similar advice you give for LT and Truck tires here,
In that PDF I mean to remember you allowed even 20 psi for Truck-tires
in the former version. Now its both for LT and TR 10 psi extra given.
My questions are :
1. did I remember this right ?
2 . why the chanche?
3 . Do you still allow 10 psi extra for ST tires above the pressure given for maximum load, for whatever reason, and if yes what reasons.

Answer fro Goodyear.

Mr. Jadatis,

Thank you for contacting our web site.

My questions are :

1. did I remember this right ? - YES

2 . why the change?

3 . Do you still allow 10 psi extra for ST tires above the pressure given
for maximum load, for whatever reason, and if yes what reasons. -

Special Trailer (“ST”) Tires
Goodyear Marathon trailer tires are widely used in a variety of towable
trailer applications and are designed and branded as “ST” (Special Trailer)
• Goodyear Marathon Special Trailer tires, with the “ST” size designation,
are speed rated at 65 MPH (105 km/h) under normal inflation and load
• This speed rating is based on Tire and Rim Association loads and
inflation pressures for ST trailer tires without a service description for
speeds up through 65 mph. (ref: TRA 2013 Year Book)
• If Goodyear tires, with the ST designation, are used at speeds between 66
and 75 mph (106 km/h and 120 km/h), we recommend the cold inflation
pressure be increased by 10 psi (70 kPa) above the recommended pressure
based on the trailer placard for normal inflation and load conditions. You
should also consult your trailer manufacturer’s Owner’s Manual for maximum
operating speed recommendations for the trailer.

o Increasing the inflation pressure by 10 psi (70 kPa) does not provide any
additional load carrying capacity.
o Do not exceed the maximum pressure for the wheel or the valve.
o If the maximum pressure for the wheel or valve prohibits the increase of
inflation pressure, then the 65 mph rated speed must observed as the
maximum speed.
o It may be necessary to dismount the tire from the wheel to determine the
maximum rated inflation for the wheel and valve. *

*Details about wheel and valve inspection:
a) If the rated (maximum allowable) inflation pressure is not visible on
the wheel, consult the wheel or trailer manufacturer.
b) Tubeless snap-in type valves, depending on the type valve, are rated for
a maximum inflation pressure of 65 or 80 psi for nominal 0.453” diameter
valve holes. If a higher cold inflation pressure is used, a clamp-in valve
such as TR416S valve (200 psi maximum inflation) must be installed.

Jennifer - Consumer Relations

Because this answer did not implied that you are allowed to go over the AT-pressure , I asked specifically for this.

Ms Jennifer,

Thanks for your quick answer and information.
But question 3 is not totally answered .
10 psi above what vehicle maker prescribes, does not comfirm that if that is for instance for a D-load tire with AT-pressure of 65 psi , that you alllow 75 psi.
So question is if you allow 10 psi above pressure given for maximum load.

For LT tires in the other link I gave it is given clearly in the document

Answer from Goodyear:

It's in regards to speed, not load rating.

This answer puzzled me so again sent them a mail.

That last answer wich I bolded, and copied here, puzzles me.
It's in regards to speed, not load rating.

So I think I did not make my question clear enaugh ( often have problem with that ).

So I will refrase my question.

In this PDF about LT and TR tires , Goodyear writes next for LT.
B. When higher pressures are desirable to obtain improved operating performance. The combined increases of A and B should not exceed 10 PSI above the inflation specified for the maximum load of the tire.

To my conclusion this means for example that if you have a Loadrange D tire with AT-pressure/ = inflation specified for the maximum load of the tire, of 65 psi, Goodyear allows to fill a cold pressure of 65 psi + 10 psi= 75 psi cold pressure. Also write that that the rimms must fullfill the demand , and I assume also the valves must be able to stand this pressure , as you already answered for ST tires.

My question is simple , does Goodyear also allow this for ST tires , as to my recollection , they did in the older PDF for ST.
So same example does Goodyear allow for a D-load ST tire also extra of 10 psi above the AT-pressure/= inflation specified for the maximum load of the tire, of 65 psi , so 75 psi.

last Answer from Goodyear,and I will keep it at this , wont ask again.

Yes, follow the guidelines as listed on the publication you attached.

Of this last answer I make that ST tires also are allowed 10 psi higher then AT-pressure because I assume the publication I attached they refer to is that of LT and Truck tires.
But I you make something else of it , feel free to discuss.
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Old 02-22-2016, 02:19 PM   #18
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Originally Posted by jadatis View Post
Goodyear inflation for Marathon ST tires.
What seems to be misunderstood here is who sets recommended cold inflation pressures for all original equipment RV trailer tires.

NHTSA vie the FMVSS clearly establishes that the vehicle manufacturer is solely responsible for setting all recommended tire inflation pressures for our RV trailer tires without regard to any specific tire design. It is further mandated that those inflation pressures be displayed on the trailer's federal certification label, in it's owner's manual and on the tire placard.

Inflation pressures less than what has been recommended is considered under-inflation. Cold inflation pressures greater than what is molded into the tire's sidewall is over-inflation.

All tire manufacturer inflation charts or special deviations from them are recommendations to those who set tire pressures. Retailers set inflation pressures for plus sized tires in accordance with tire industry standards.

Deviations from the normal recommendations are for special circumstances.

When you find information saying to air your tires to the load carried you are reading something from another regulation that does not apply to any tires originally fitted under the FMVSS regulations.
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Old 02-22-2016, 02:44 PM   #19
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Answer to Airdale

cant find the quote you write is mine, but not important.

I myself value laws of nature more then laws and regulations of the organisations you mention.

To write it blunt, in the middelages the king sayd that the earth was flat , People who dared to question that where hanged. But even then the earth was round.

To come back to tires. If practice prooves that Trailer tires often fail, and you can lower that chanche by using higher pressure , you do it right to laws of nature , but might come into trouble with the knights of tire-organisations.

And the tiremaker allow that 10 psi higher pressure ( as far as I concluded) so everybody happy. You dont go over what the tiremakers allow, and you have a saver pressure with lesser chanche on failure and the missery that goes with it ( best case damage to trailer, wost case accident with injuries and even death people)
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Old 02-22-2016, 03:24 PM   #20
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Originally Posted by lbrjet View Post
Don't go over the sidewall max.

2010 F250 5.4L 3.73
2011 Flagstaff 831FKBSS
Equal-i-zer 4pt 12K

X a billion.

2016 Sabre 36QBOK
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pressure, tire

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