Over-inflated tires are a bad idea

A gentle reminder, if you reset your tire pressure, be sure to reset the tire pressure indicator system:


Bob Wilson

 

I have a couple of general questions for purposes of clarification:

1. I have always considered the term "overinflation" to mean cold pressure at any point above the sidwall max pressure. It appears others use the term for any situation where the cold pressure is higher than the number recommended by the manufacturer. Is there any consensus on the use of this term?
2. Why would the manufacturer recommend a specific tire pressure, regardless of the tires used? I know that most tires have max concentrations of either 44psi or 51psi, but is it also the case that certain sizes of tires are always a specific pressure?

 

TO ALL - I used to run SCCA and i'll tell you that for maximum traction/braking, we used to "raise the antes" and pump up our tires to 46 psi PLUS.......... with an increase to acceleration and braking.

Now, I have to admit, for everyday street driving, i was VERY concerned when i hear about some drivers using 50+ psi's in their tires. Here are my thoughts..............AGAIN, MY THOUGHTS ONLY.................for those who run the stock goodyear integritys...........42/40 should be GREEEEAATT.... i dont think you will ever have a problem as I do this for my daughters car. for me, i run an aftermarket performance tire - the BRIDGESTONE potenza GO19 Grid and i've pumped them up to 46/44. After 10K miles, i notice NO abnormal wear. Same with my kids.

Again, everyone is out to give you advice. the bottom line is......take what you like, use what you like and come to your own conclusions. Incidentally, many of the GURUS that i learned from are ones that have posted here. bottom line, they are correct.

Cheers

 

I've noticed that some of the GO19 Grid tires have max pressures at 51 psi (I think they are all the 16" variety). Are yours 44psi or 51psi? Would it make any difference to you (meaning, would you go higher than 46/44 on tires rated at 51psi)?

 

how observant you are. NO, i did not notice a difference running higher psi's, soooooo, i just chose to run what i felt was safe.

cheers

 

For those who take Toyota's placard as gospel, they recommend 1 pressure for 1 tire. If that is the best pressure for the best tire why do so many "upgrade"? I suspect many of us agree with the posted article in general but disagree on the specifics.

 

Fortunately this is not what we experience in the real world...

http://priuschat.com/forums/gen-ii-...24-integritys-over-35k-miles-50-psi-pics.html

http://priuschat.com/forums/gen-ii-...g/63223-20k-miles-nokian-i3-tires-50-psi.html

 

If Toyota itself doesn't take the placard as gospel -- they delivered it to me with 5psi extra -- then I won't either.

 

The dealership always 'restores' my tire pressures to what's 'proper'. I've asked them repeatedly not to touch them, but they insist it's a liability issue. I don't think they really know or care what the pros and cons are.

 

I just replced my original integriies at 61k. I ran them at 44psi the whole time and the edges wore out first.

 

Therein lies the funny/sad/irony ... because inner/outer tire tread wear (presuming alignment is correct) is a sign of under inflated tires. Now just think how quick the integrities would of died, if you'd of had the pressures down in the 30's following the manufacturer's recommendation. When I think of all the 10's of thousand of miles in tread life that were lost, because of these 30-ish psi max pressures, it makes me smack myself. But 60k on the goodyears? you did GREAT!

.

 

Wow, research and evidence. This post owns this thread.

 

I've got about 60K on my Hydroedges, at mid-fifties PSI, and
still plenty of meat left all the way across the tread. Well,
on three of them at least, since one picked up a fatal puncture
on the last roadtrip that was pronounced "too close to sidewall
to patch reliably". Now I've got some cheap POS korean crap
on one corner which is larger than the three other HEs and is
throwing my hack-TPMS off, but I'll live with this for a while
rather than replace all four feet prematurely. "Premature" at
60K on the remaining tires?? You betcha. This one will probably
wear down faster to match, assuming no further disasters.
.
The puncture had nothing to do with inflation pressure; the
injury was an almost invisible three-armed slit going straight
into the treadblock, with the offending object missing when I
noticed the speed-mismatch and pulled off, and would have been the
same regardless of inflation pressure. Whatever the object was, it
was *sharp*, and even though I try to check where I'm about to back
into it was raining pretty hard that day and I was on some unfamiliar
highways so there must have been some metal piece of junk off a farm
implement or something laying in a little turnaround I used. That
TPMS-diamond thing totally paid for itself in terms of the design
and build time that day, as it alerted me early to the tire going
soft and let me hazard the guess that I could make it another mile
to the drier shelter of a truck-stop fuel island canopy to swap on
the ugly yellow donut.
.
Consider this: 44 PSI "cold". Yes, I've posted this before, but
it bears repeating. I bring my tires to sidewall in -5 degrees
with wind-chill in Boston, and then over the next day and a half
drive to Florida where it's 85 and blasting sun on the pavement.
Where's my tire pressure now? Well north of 50, and when hitting
the bumps on some of the crappy old concrete-slab roads down there,
easily seeing pressure pulses pushing 100 PSI. Do they explode at
45.178 PSI? No. Factor of at least five in construction safety,
even in fairly cheap tires, and very happy in countless ways at
sidewall-plus.
.
_H*

 

hobbit, thanks for the link ... especially the picture of your goodyears. It reminded me of our integrity's ... by the time 2005 rolled around.

.

 

Never mind the pressure sensors - running with a different tire on one wheel doesn't sound safe to me, especially if it's a different size. I'll let the experts chime in with more learned opinions, but I hunch your emergency braking and handling would be seriously compromised. Maybe not as badly as with the old sin of mixing radials and bias-plys, but I don't like the sound of that at all.

 

It's not *rated* a different size, it's still a 185/65R15 but
a> since it's a newer tire and b> since the Hydroedges proved
to *not* have the rated 855 revs/mile but 1.2% more than that
[originally] in the first place, the oddball tire is therefore a
slightly different physical size but not in a way that affects
handling. Having put over a thousand miles on it in the meantime
on my subsequent wandering path home including a healthy chunk of
northeast mountain twisties, I'm not particularly worried.
.
I'll rotate it to the front soon and my MFD error might
actually drop from its current offset of 1.4% down to 0.7%
or thereabouts, what a concept. I haven't actually measured
the inflated circumference of the new one but I suspect it'll
be more in line with what the original Integrities were.
.
_H*

 

Only car I've ever lost to tire failure was inflated to placard pressure, brand new tires, and checked with a gauge I'm still using (along with several others for confirmation) within 24 hours before failure, and no signs of pressure loss while driving until the blow out on an interstate curve with an 18 wheeler alongside. The so called "professional engineer" doing the post crash exam claimed it was under inflation, but I'm an engineer and know that he was full of shit since I personally did the check out as I do with all new tires looking for valve stem/bead leaks. Must have gotten his PE out of a cracker jack box. The failure marks of the material at the bead and the sidewalls don't match with his observations of low pressure operation (I kept the tire while considering litigation against the manufacturer, and I routinely replaced under inflated tires while working construction in college so I have some knowledge of how this works in the real world.) Bridgestone's compound was bad--good luck to any of you running Potenza's, you couldn't pay me enough to put one of those POS's on a car again, damned Firestone crap compound. My estimation of PE's is not very high based on this and other experiences.

How many tires have any of you seen fail to overinflation? I've seen exactly one...and that was because a dufus put 90+ psi in a dump truck tire split rim without it properly seating against the split rim. (Actually the tire itself survived and I reused it, but the rim had to be scrapped.) He was lucky it didn't take his arm off while inflating it, and I had warned him to be careful with that particular rim since it was questionable, but he didn't listen. I told him to stop if it didn't seat by 60 psi and we would chuck the rim.

 

its funny, but i learned most of what i know about tire pressures from playing "NASCAR Racing" on the PC. it gives you tire temps as Bob stated from left, center and right. since most tracks (at least in the game) run counterclockwise (or perpetual left turning) higher temps on the right side means either bigger wedge (a thing shoved into the suspension to make car lean into the turns which shifted the center of gravity) or more tire pressure.

in the game, if tire pressures were too low, tires had to be replaced more often which meant additional pit stops, etc... the game settings were supposed to be modeled on real physics models and every adjustment available to a real pit crew, we also had...

now, granted, i often setup a car that i couldnt do two laps without at least one spinout... very frustrating at times, but also educational

 

Beside the point of the thread, it sounds like his first mistake was not inflating it inside a safety cage. That was standard practice (and presumably still is) and perhaps legally required for split rims when I was in the tire business many years ago.

Back on topic, when I was in the business I never saw a tire failure that could be attributed to overinflation. Failures from underinflation were routine.