Tire inflation advice needed

[Rolf]

Originally Posted By: CapriRacer
But this doesn't change the fact that the placard pressure specified enough inflation pressure to carrying the max load of the vehicle - so it was not the cause of the failures - and the link you provided proves that!


The reason why Firestone recommended 30, not 26, is that - as the NHTSA's own studies show - 25% or so of drivers have at least one seriously underinflated tire.

If you put 30 or 32 in, and fail to check the tires for 6 months, and they drop to 26, you're okay. If they drop to 24, you probably are still okay. Start at 26, and you're trouble right away.

That is the cause of the failures, not some imaginary stress factor in tread plies.

The other factor, IMHO, is that inexperienced drivers - e.g., most women and a lot of men - disregard the warnings their tires give them.

Tread separations typically exhibit when they begin as vibrations or thumping. Disregard that and in 5 or 50 miles you have the entire tread separate.

There is simply no doubt in my mind that 95% or more of the Firestone tire failures lay at the feet of the operators.



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[CATERHAM]

Tire failure due to overinflation is virtually nonexistent.
Tire failure due to underinflation is all too common.

Unless you check your tire pressures weekly, I find it best to add a few lbs over the mfg rec's.

 

[CapriRacer]

Originally Posted By: Rolf
The reason why Firestone recommended 30, not 26, is that - as the NHTSA's own studies show - 25% or so of drivers have at least one seriously underinflated tire.

If you put 30 or 32 in, and fail to check the tires for 6 months, and they drop to 26, you're okay. If they drop to 24, you probably are still okay. Start at 26, and you're trouble right away.

That is the cause of the failures, not some imaginary stress factor in tread plies.

The other factor, IMHO, is that inexperienced drivers - e.g., most women and a lot of men - disregard the warnings their tires give them.

Tread separations typically exhibit when they begin as vibrations or thumping. Disregard that and in 5 or 50 miles you have the entire tread separate.

There is simply no doubt in my mind that 95% or more of the Firestone tire failures lay at the feet of the operators.

.


I'm a little unclear on your position. Is it the following:

1) The placard pressure is OK If so, I agree.
2) That people neglect tire maintanence and the result is underinflated tires. If so, I also agree. BTW, the study you cited was the basis for mandating Tire Pressure Monitoring Systems (TPMS) - a much dispised item on these web pages.
3) That the Firestone tire failures were mostly the result of underinflation and not the result of a quirk in the design. If so, I disagree, and we could have a very interesting discussion on this point. You've presented some data that supports that position. But we do not need to go into that now.

 

[Rolf]

Originally Posted By: CapriRacer
I'm a little unclear on your position. Is it the following:

1) The placard pressure is OK If so, I agree.


Firestone's advice of a placard showing 30 psi rather than 26 psi was correct and would have avoided much of the ensuing problem.

Quote:
2) That people neglect tire maintanence and the result is underinflated tires. If so, I also agree. BTW, the study you cited was the basis for mandating Tire Pressure Monitoring Systems (TPMS) - a much dispised item on these web pages.


As a direct result of the Firestone tire fiasco.

Quote:
3) That the Firestone tire failures were mostly the result of underinflation and not the result of a quirk in the design.


That is correct.

The tires in question were statistically more likely to have a tread separation than many other tires, but the percentage was still within reasonable bounds.

However, when underinflated and then driven at high speeds by individuals likely to ignore every warning of impending disaster, and also unlikely to negotiate a blowout properly (e.g., slamming the brakes on), such a failure was most likely going to result in death or serious injury.




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[Geonerd]

Interesting Firestone / Exploder reading!


There is nothing magical about the factory spec. door jamb pressure.

My Accord's tires definitely suffer edge wear when inflated to the suggested 32 PSI. When replacing those tires, I started paying attention to the tread depth, checking once every few weeks. 35 PSI was better, but still fractionally too low for even wear. I've settled on 39PSI as a good compromise between ride quality, tire wear, and (slight) fuel savings. I tried 45 PSI, but the wear and tear on both car and driver was a little more than I was comfortable with. (If I spent lots of time cruising the interstate, I'd have no issue with 40+ pressures.)