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JohnBoyToo · 10-02-2012, 11:33 AM

according to this: http://www.tirerack.com/images/tires...plications.pdf

"Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load."

so the 80 lb sidewall max can have 90 psi put in it ?!?

nosticks · 10-02-2012, 12:14 PM

I didn't know that. Thanks for the web site posting of the bulletin.

JohnBoyToo · 10-02-2012, 12:43 PM

That statement is a little ambiguous so I emailed Goodyear....
and while waiting on an email response O called and reworded my question to say "does that mean 10 PSI over the max sidewall pressure ?"
and they said yes, with the caveat that the rim can withstand that pressure....

Now, how do you find out what rim comes on a new rv and how much pressure your rim can handle ?!?

wa8yxm · 10-02-2012, 02:48 PM

When you read that '90 PSI max" or whatever it says, PLEASE READ THE FULL SENTENCE:

If you read just the part you mentioned above you will over inflate your tires and wear them out faster

Maximum load XXXX Lbs. at Maximum pressure of YY PSI.

Less Lbs = Less PSI.

nosticks · 10-02-2012, 03:36 PM

Johnboytoo, The rim should be stamped on the back side as to max pressure. My 16" rims are stamped 110#. At first it was hard to see, but with a light on the back of one of the spokes was where I found it.

JohnBoyToo · 10-02-2012, 06:49 PM

no need for caps - I did read the full sentence - actually I read the whole document
and more documents and also called two sources I've used before...

All I can tell you wa8 is what the tire rack dealer said....
and the goodyear store down the street I've used for a while...

I'm waiting on the response from goodyear to be sure....

but it sure seems like the official documentation from goodyear says there is a cushion built into the tires for 'warm up' so cold psi means COLD - not driven at all...
and max press CAN be exceeded by 10 psi according to that document...

hard to misunderstand this portion:
"10 psi... above the recommended pressure for the rated maximum load."
the rated max load is only at the max pressure on the sidewall
and in my case it's 80 psi... so my kollege math says 80+10 = 90

)

will wait and see, but sounds promising...

JIMNLIN · 10-02-2012, 07:20 PM

Old old info. At one time it was only a couple of ST tire sizes that Goodyear recommended doing so but a reduction in load was required for the higher speeds.

Adding 10 psi above 80 psi cold pressure has the tire at 90 psi then run down the road at interstate speeds has the tire growing another 8-10 psi to 98-100 psi. IMO not a wise choice.

Dunner · 10-02-2012, 07:47 PM

Better solution is to put LT tires on and inflate them to sidewall pressure.

azdryheat · 10-02-2012, 08:15 PM

Quote:

Originally Posted by Dunner

Better solution is to put LT tires on and inflate them to sidewall pressure.

Midniteoyl · 10-02-2012, 08:29 PM

Quote:

Originally Posted by Dunner

Better solution is to put LT tires on and inflate them to sidewall pressure.

Midniteoyl · 10-02-2012, 08:31 PM

And, just so no one gets the wrong idea, we are talking about Trailer Tires. Specifically, Goodyear Marathon 'ST's... which are one of the um, 'Chinese like' ones. Goodyear says to up the PSI becuase they found that they would have to otherwise derate the weight and/or the Max speed, or both.

Dunner · 10-02-2012, 08:44 PM

Never had another tire failure after going to LT tire on my trailer.

JohnBoyToo · 10-03-2012, 09:30 AM

Yes, many opt for LT tires....
but if you're not ready to spend another $750 to $1000 right now,
and want to make it as reliable as possible...

if May, 2011 is old, then what am I ?

again, just trying for all the information available... still waiting on goodyears response.