Still More on Tire Pressures

[john bush]

> Santa Claus brought me a paperback on RV's in general
> that has a chapter addressing the care and feeding of tires.
> The author cites the same minimum 80 psi requirement
> for cold "LT" pressures but on goes further to address
> use of pressures ABOVE the stipulated minumum

A query was sent to the truck tire gurus at the Goodyear
WEB site regarding that proposition; their response received
yesterday just says:

"We would not recommend that you exceed the maximum allowable
air pressure under any circumstances. If you feel you are too
close to the maximum load carrying capacity you would need
a different load range/size."

Anyone need a slightly used, not too useful RV reference? It might
prove useful to shim a wobbly picnic table leg or ........?

End of story.

John Bush
75 PB Sunol, CA

 

[travis martin]

> "We would not recommend that you exceed the maximum allowable
> air pressure under any circumstances. If you feel you are too
> close to the maximum load carrying capacity you would need
> a different load range/size."

I dunno; I think this raises more questions than it answers. This sounds
like a canned PR dummy response to evade liability issues, not the reasoned
answer of a tire engineer. Maybe if you called them and made a pest of
yourself you could get a real tire engineer to think about the question.

Better yet, perhaps Emory could take this on; he obviously speaks
"engineer-typese" and did wonders with Statpower.

Travis

 

[travis martin]

> Travis - I'll be happy to talk to some tire manufacturers re inflation
> pressures. I did not talk to Statpower but rather it was Henry Davis that
> has initiated and currently has an ongoing dialog with them about failure
and
> possible causes of failure.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM

Woops! Sorry 'bout that Emory! That's what comes of not having met all you
guys face-to-face!

But why not jump in? If you can actually get one of their tire engineers on
the horn, he could probably illuminate the subject. My only point was that
the answer that John reported didn't sound at all thought-out; more like a
liability-limiting disclaimer.

My understanding from, I believe, Tom Warner's recent posts is that the
inflation number molded on the side of a passenger car tire is intended to
be a maximum, but that truck tires and presumably the light truck tires
being discussed here have a minimum pressure rating. My Michelin XPS Ribs,
for example, say "maximum load at 75 psi ...." (2680 I think) but my point
is that we are to infer that this is a minimum inflation pressure. But it is
entirely possible, even likely, that I misunderstood. Lord knows there have
been plenty of opportunity for this to get scrambled. That's why I'm
suggesting that an "engineer type" could talk to a real honest-to-goodness
tire engineer and get some data.

By the way, I also subscribe to a Corvette list where a recent thread
thrashed out the relative merits of the different grades of gasoline. One of
the other list members is a peroleum chemist actively involved in that and
posted a long response; another member then obtained permission to put the
treatise on his site, much as some of our own members have done. I would
like to see some of you guys peruse it and see what you think; you might
find it interesting. Much of what he says will directly transfer to the GMC.

http://www.vettenet.org/octane.html

I may have posted this earlier; I forget. I meant to...

Travis

 

[robert schoner]

Please note the difference in the two references:
The RV Book: "MINIMUM 80 psi requirement"
Tire Gurus: "don't exceed MAXIMUM allowable pressure"

According to Wes Caughlin in Motorhome: Light truck tire specifications
state the MINIMUM pressure for the MAXIMUM load. Different from passenger
tires that state the MAXIMUM PRESSURE. He recommends 10 psi over the
minumum pressure for the max load on the LT tire sidewall as a safety factor
for pressure loss etc. Please remember that there is a maximum PRESSURE
specification for the rim (wheel) that must not be exceeded as well.

Bob Schoner
Still looking for the "Perfect" GMC
- -----Original Message-----
From: John Bush
To: GMC Net
Date: Tuesday, September 28, 1999 8:07 AM
Subject: GMC: Still More on Tire Pressures

>
>> Santa Claus brought me a paperback on RV's in general
>> that has a chapter addressing the care and feeding of tires.
>> The author cites the same minimum 80 psi requirement
>> for cold "LT" pressures but on goes further to address
>> use of pressures ABOVE the stipulated minumum
>
>A query was sent to the truck tire gurus at the Goodyear
>WEB site regarding that proposition; their response received
>yesterday just says:
>
>"We would not recommend that you exceed the maximum allowable
>air pressure under any circumstances. If you feel you are too
>close to the maximum load carrying capacity you would need
>a different load range/size."
>
>Anyone need a slightly used, not too useful RV reference? It might
>prove useful to shim a wobbly picnic table leg or ........?
>
>End of story.
>
>John Bush
>75 PB Sunol, CA
>
>
>
>
>
>