Tom,
The letter you refer to on Billy Massey's site is from General Tire Company.
It refers to their tire only and only the 8.75x16.5. Extrapolation of this
letter to 225x16s or any other tire cannot be justified. If it applies to
all tires we should see a General Motors Corporation letter or letters from
each tire company saying the same thing. The certified tests should be
documented somewhere. Instead we have other companies such as Michelin
giving quite the opposite advice. Tell me where to find explicit written
data from GMC about GMC's tire recall and its application to all tires used
on a GMC.
Bob McLaughlin
- -----Original Message-----
From: owner-gmcmotorhome
[mailto
wner-gmcmotorhome]On Behalf Of tom warner
Sent: Friday, April 07, 2000 9:33 PM
To: gmcmotorhome
Subject: GMC: How much longer is this tire myth going to hand on and
confuse people
Chuck trying to put this incessant regurgitation of the myths on the proper
tires and tire pressures or the GMC motorhome to rest is nothing short of
frustrating. How many times have we got to go over this before everyone
understands. IT HAS NOTHING TO DO WITH HOW MUCH WEIGHT IS ON EACH TIRE.
CERTIFIED TESTS HAVE PROVEN IT SHOULD BE AN LT225/75R16 ALL STEEL TIRE
INFLATED TO 80PSI.
The supplied recall sticker from General motors did not say sometimes it
should, it did not say, chuck has the option, it did not even say that it is
tom warners opinion. It was very clear.
Why are we still discussing this?Look at the General Motors letter and
recall sticker and tell me what you dont understand and where you keep
getting these crazy ideas about tire pressure?
http://www.web-access.net/~bmassey/tire_recall.html
>Michelin books and Goodyear web page agree on tire pressure verses load on
>these tires. Michelin book recommends measuring the load on each tire
>individually for a fully loaded RV and then "For control of your RV, it is
>critical that the tire pressures be the same across an axle". To me, that
>means measuring the full GMC on each front wheel and both back wheels as a
>set and determining what the correct pressure should be from the chart on
>that set of axles. So you should wind up with two different tires
pressures,
>one for the front axial and one for the rear axials.
>
>They also recommend a calibrated dual end gage.
>
>The cold inflation tire pressures verses the loads for single LT225/75R16:
>
>35psi/1500 lbs
>40psi/1650 lbs
>45psi/1790 lbs
>50psi/1940lbs
>55psi/2060lbs
>60psi/2190lbs
>65psi/2335lbs
>70psi/2440lbs
>75psi/2560lbs
>80psi/2680lbs
>
>They also recommend increasing the recommended tire pressure by 5 psi "to
>accommodate temporary shifting of load from side to side which is common in
>RV's".
>
>"A tire that is underinflated will build up excessive heat that may go
>beyond the prescribed limits of endurance of the rubber and the radial
>cords. This could result in sudden tire failure. A tire that is
>underinflated will also cause poor vehicle handling, rapid and/or irregular
>tire wear, and an increase in rolling resistance which results in a
>decreased in its fuel economy."
>
>"Overinflation will reduce the tire's footprint or contact patch with the
>road, thus reducing the traction, breaking capacity and handling of the
>vehicle. A tire that is overinflated for the load that it is carrying will
>also contribute to a harsh ride, uneven tire wear, and will be more
>susceptible to impact damage."
>
>Lowering tire pressures to match their load on our light 23' was the
>cheapest and fastest way to cut down on darting in wheel ruts.
>
>Year of manufacture is currently the last three numbers of the DOT number
>system. The first two numbers are the week of the year and the last number
>is the year. That will be changed in the future to a four number system
with
>the first two numbers being the week of the year and the last two being the
>year. "In cooler, clean air locations, the expected tire life will be
>longer than in high temperature, high ozone areas".
>
>Hope this information clears the air on what is the correct tire pressure
>for your GMC. I know mine not only rides better, but is a lot less
sensitive
>to road ruts with the tire pressure lowered to match the tire load + 5 psi.
>
>
>
>
