Low Tire Pressures

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Filled up some newer Nokians to 34 psi a few weeks ago. Someone commented one of the front tires looked low. Checked the tire pressure and it read 28.5 psi. Checked all tires and they all read 28.5 on the digital tire pressure gage. When I filled them to 34 it was after some hwy miles on a hot day. The tires have an "A" temperature rating. Hoping I don't have leaks around the rim. Had them installed at QuickLane who took his time and one of the best according to the advisor.
 
You lose 1 psi per 10 degrees F due to physics of gases (air). Also, driving around generates heat and pressure too. You put in 34 psi on a hot day after some driving. So attribute about 2 psi to driving around heat generated, and 4 psi due to 40 degrees hotter that hot day, and you just demonstrated physics. Deflategate all over again here.... no scandal.
Knowing that, one can adjust their thinking about tracking pressure.
Also, sometimes its the Schrader valves, not the tires.
 
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If faulty and leaky, I doubt all four tires would lose air at the same rate.
We've recently had temperature swings going from 80s to 60s.
Also, you mentioned filling them to 34 after hwy driving on a hot day. That'll go down to a lower number in cooler weather.

It's best to check tire pressures in the morning before driving and before the sun warms them.
 
Thanks, they put in new valve stems when tires were installed. Since all tire pressures were the same I thought that was a good sign. Car is outside all the time and has had a fair amount of hwy miles put on it recently.
 
I set my tire pressure before driving in the morning. I use a good gauge. As stated tires increase or decrease in pressure at a rate of ~ one psi for every 10 degree f. change in temperature. Ed
 
Tires can lose around 1psi a month normally, also 1psi per 10f

my tires were going from 36 to 40 while driving..
well outside temp dropped and suddenly they were at 32-33 36 after extended driving.

Also these firestone destination AT seem to lose abit more air than other tires I've had previously.

If its the 2005 with alum wheels.. they can lose quite abit of air from bead seat corrosion.. but all of them dropping the same makes that unlikely.
 
Keep in mind that the sidewall rating is "COLD" so even at what most refer to as "max sidewall" it's still designed for expansion. I usually only see about 3 PSI swing on my Cruze's TPMS from morning/cold to the peak of a mid-day highway run, but that they all dropped consistently sounds much more like expansion/contraction than leakage.
 
Originally Posted By: SatinSilver
When I filled them to 34 it was after some hwy miles on a hot day.


That's it right there.
 
Here's a page from a Toyota TSB you might find helpful:

TP_TSB_11OCT17_zpsqctggvtf.jpg


HTH
 
gaiginnv, I've never seen a chart like that. Kudos to Toyota. However, its too complicated for the average John Q. Public out there.
Its even able to fool us because the "O deg F" shown on the left vertical axis is really the DIFFERENCE between room temperature and the ambient outdoor temperature you are checking the tire at, NOT 0 deg F winter temperature.
Want it complicated a bit more(?): A tire parked in shade vs. a tire in full sunlight will read about a couple of psi different.

In summary: The B-pillar placard temperature is really the 70 deg F pressure. Now add or subtract 1 psi for how hotter or colder the ambient air temperature is, and put the tire in the shade (no sun), and let the tire cool for at least a couple of hours after driving. Still too much for people to follow. Soccer moms don't want any of this.
 
Originally Posted By: oil_film_movies
gaiginnv, I've never seen a chart like that. Kudos to Toyota. However, its too complicated for the average John Q. Public out there.
Its even able to fool us because the "O deg F" shown on the left vertical axis is really the DIFFERENCE between room temperature and the ambient outdoor temperature you are checking the tire at, NOT 0 deg F winter temperature.
Want it complicated a bit more(?): A tire parked in shade vs. a tire in full sunlight will read about a couple of psi different.

In summary: The B-pillar placard temperature is really the 70 deg F pressure. Now add or subtract 1 psi for how hotter or colder the ambient air temperature is, and put the tire in the shade (no sun), and let the tire cool for at least a couple of hours after driving. Still too much for people to follow. Soccer moms don't want any of this.


Just about all of that is incorrect
spankme2.gif
 
Same thing recently happened to me. The Sonata's tires were around 29 psi which I usually keep at 36. But my Jeep's tires were still at 35 psi
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but it sleeps in the garage all the time.
 
Right after I put some Cooper's on my Buick they were losing 2-4 pounds every 3 or 4 weeks which I thought was a little excessive but after a while this stopped. Now I only need to adjust them 3 or 4 times a year. I'm not sure what happened here but I'm guessing they sealed better or settled on to the rims over time due to the rims being old or dirty.
 
Originally Posted By: gaijinnv
Just about all of that is incorrect
spankme2.gif

If you still disagree with Toyota, then I suggest you go back and study engineering. The Toyota chart is correct. What parts of it are you not understanding?
 
Thank you everyone for the comments. Some very good points were made. Checked the psi this morning of just one rear tire and it was 34.5. When I filled all the tires yesterday to 35 they were warm from getting off the highway, maybe 10 miles. Temp yesterday was in the low 70's. I only checked one tire this morning since I didn't feel like checking all of them. I will check them again next week.

My mom commented the other week the front tire looked low. Which is why I checked it. When I saw 28 psi I thought for sure I'd be taking it in for a leak repair at Discount Tire. But when all of them had the same psi I knew that probably wasn't the case.

A week or two ago we saw some temps in high 30's and some highs in upper 80's. Plus a fair amount of hwy driving. Probably about 2000 during the last air fill up.
 
Originally Posted By: oil_film_movies
Originally Posted By: gaijinnv
Just about all of that is incorrect
spankme2.gif

If you still disagree with Toyota, then I suggest you go back and study engineering. The Toyota chart is correct. What parts of it are you not understanding?


Yes, the Toyota chart that I posted IS correct. The way you tried to explain it is completely wrong
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Originally Posted By: gaijinnv
Originally Posted By: oil_film_movies
Originally Posted By: gaijinnv
Just about all of that is incorrect
spankme2.gif

If you still disagree with Toyota, then I suggest you go back and study engineering. The Toyota chart is correct. What parts of it are you not understanding?


Yes, the Toyota chart that I posted IS correct. The way you tried to explain it is completely wrong
33.gif



If I may: I think gaijinnv was mostly objecting to your characterization of the placard pressure being a 70°F temperature. That pressure is applicable regardless of the outside temperature.

That means is that every time the temperature changes, the pressure has to be adjusted - at least for those of us who are anal retentive! The rest of the world will fill the tires to a reasonable pressure so that it accounts for predicable temps in the season we are in and adjust the pressure when those change - like now, when we are transitioning from summer to winter.
 
Originally Posted By: CapriRacer
I may: I think gaijinnv was mostly objecting to your characterization of the placard pressure being a 70°F temperature. That pressure is applicable regardless of the outside temperature.

I see where gaijinnv and you are confused. Look at the circled-5 on the Toyota chart. What does it say? Workshop Temperature! The DIFFERENCE.
Therefore, reading the chart, see that 0 deg F is at 0 adjustment when there is 0 difference between the outside temperature and the Worshop Temperatue indoors at ..... you guessed it... about 70 deg F.
Get it yet?
 
Originally Posted By: oil_film_movies
Originally Posted By: CapriRacer
I may: I think gaijinnv was mostly objecting to your characterization of the placard pressure being a 70°F temperature. That pressure is applicable regardless of the outside temperature.

I see where gaijinnv and you are confused. Look at the circled-5 on the Toyota chart. What does it say? Workshop Temperature! The DIFFERENCE.
Therefore, reading the chart, see that 0 deg F is at 0 adjustment when there is 0 difference between the outside temperature and the Worshop Temperatue indoors at ..... you guessed it... about 70 deg F.
Get it yet?


No confusion here, you are the one who does not get it.

Substitute "ambient" for "workshop" and it should be clear that the values on the x-axis are the difference between the ambient temperature at which the tires are being inflated and the near-term expected ambient temps in which the vehicle will be operated.

For example: If one were to inflate their tires at 30 DEG F and expect the ambient temp to remain the same, then the difference would be 0 degrees and the required adjustment would be 0psi. Note this has nothing to do with your suggestion that these numbers are at 70 DEG F.

Further, the recommended cold tire inflation pressures on a car's door placard are pressures at ambient temp, NOT at 70 DEG F as you suggest.

Claro?

HTH
 
Movies,
I think gaijinnv's interpretation of 'confusing' Toyota quote is appropriate.

At times, writing 'manual' in language not of your native-tongue could be challenging!


Item 1- should read as:Cold Tires ...... and Parked Outside (add) , Inflation Temperature
Item 5- Workshop Temperature should read as : Inflation Temperature.

Just my
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.
 
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