Quote:
Originally Posted by RidingOnRailz
So are you suggesting that 26psi cold was an acceptable pressure, but that anticipated loads per axle weren't taken into consideration?
Confused..
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Let me put it like this:
Tires on the 1997-1999 Ford Explorer: *
P235/75R15 @ 26 psi = 1594# = size in question!!
P225/70R15 @ 30/35 psi = 1475#/1594#
P255/70R16 @ 30 psi =1913#
Tires on the 1997-1999 Chevy Blazer:
P205/75R15 @ 35 psi = 1452#
P235/70R15 @ 32 psi = 1643#
* - Tire load carrying capacities at the pressure specified INCLUDING adjustment for use on an SUV.
Please note that the load carrying capacity of the tire in question is NOT the lowest value.
I didn't show other vehicles, nor do I have the GAWR's, but at the time (Fall of 2000) I did ALL of the vehicles and had access to the GAWR's (which I don't now) and I gave that information to our VP of quality for the tire manufacturer I worked for. I was asked to do this to be sure we knew what was going on - particularly since Firestone was pointing out the pressure issue. Looks like they did a good job of obscuring the facts as the argument continues to sway people even 20 years later.
What did come out of this analysis was that - using our own data - certain tire combinations showed NO returns for the same time period - and those returns had one thing in common = H and higher speed ratings.
Our conclusion at the time was that it wasn't the pressure on the Ford Explorer that was the issue. I wasn't in a position (at the time) to know what the issue was (somebody in our organization did!), but I later found bits and pieces on the internet to get enough to make a coherent story - which lead me to write up the webpage I cited above.
So for 20 years I have been saying that the pressure was not the issue and the combination of the design of the tread pattern and the way the plant processed the rubber WERE the issue. This is also what the government (NHTSA) found.