Newer cars have a TPMS and warn you when the pressure gets low. Now that
cold weather is here,check to see that your tire is at least the
recommended pressure. I forgot about it and this morning it was 7
degrees. One tire was 1 pound under and set off the warning. It would
not reset after driving as it had to come up even more than driving did.
Filled it up when I got home.
Not a major deal as I knew the pressure was adequate to drive, but it
annoys me to have that yellow light on when driving. I understand this
is a common happening for the first really cold snap.
What's more annoying is when the sensor fails and it costs over $100 to
fix it at the dealer. Happened on my wife's Subaru and even though I
set pressure on all the tires a few pounds higher, would not stop.
Another example of dumbing down America by requiring these sensors.
I am just glad the state inspection does not require them to work. I have a
2008 car with about 25,ooo on it and a 2007 truck with about 55,000 on it
and both have a bad sensor in atleast 1 tire. Probably a dead battery in
them. A tire place told me they would be about $ 60 for each tire. I am not
about to spend around $ 500 or more just for some stupid sensors if I don't
That is similar to a car I had years ago . A milage counter came on around
50,000 that was to replace a sensor that later was determined not to need
replacing at 50,000. The factory fix was to cut a wire that turned the
It all started when we switched from candles to oil lanterns. Then to
gaslight. Then electricity. It was bad enough that the city folk used
it, then FDR decided to inflict it on the rest of America, too.
Don't get me started on modern medicine. My great grandparents died of
TB. They didn't need no rescuing with those newfangled antiobiotics.
We're back at Costco every week or two having them add nitrogen to
the tires. On a cool day (30-ish in the AM), tire pressure (all
around) will be low. However, on a warm/normal day (80-ish in the PM),
pressures will be high -- TOO high if we'd added nitrogen on one of
those colder mornings!
[I think it's 1 psi per 10 degrees F?]
And, the Costco tire droids want to "overfill" by ~3 psi claiming
the tires are "hot" now that you've driven on them. So, instead
of 35/33 psi, they'll fill to 38/36 psi. Then, the ambient
temperature climbs 40 or 50 degrees and the tires are considerably
So, bleed out some nitrogen to bring them down to ~40/38 ("hot")
and hope we don't get another cold day to bring them *down*, too far.
If you are getting that kind of pressure change they are NOT using
Nitrogen is very thermally stable pressure-wize,The calculations for
this change are based on the Ideal Gas Law. A good rule of thumb is
this: For every 10 F degree change in temperature, the pressure will
change by 1.9%. With dry nitrogen,if a tire is filled to 32 psi at a
temperature of 75 F degrees and the temperature drops 10 degrees, the
tire pressure will drop to 31.4 psi; a difference of .6 psi. If filled
at 65 degrees to 32psi, and driven untill the tire temp is 95 degrees,
the pressure will rise to 33.8psi
A 50 degree temp rise will only add 3psi - which is no problem at all.
With air which contains moisture, you will get more pressure change.,
but not a huge amount.
My hunch is leakage. TPMS set without proper torque when installed can
leak air. I have TPMS on summer and winter tires on separate OEM rims. Never
have such problem. I usually over inflate by 5% or so. You'd feel the
ride is deffirent over inflating by ~10% or so.
10% ovderinflation is peanuts.
Most cars ride and handle much better (and tires last longer)
with10-15% overinflation. Spec on my Taurus is 32. I run a minimum of
36 - usually 38PSI Stops the "tucking" on turns and makes it handle a
whole lot nicer. Doesn't hurt the ride either.
On 1/5/2016 9:18 PM, email@example.com wrote:
It's 30 degrees. Tire monkey inflates tires to 38/36 psi (instead of 35/33).
*Ambient* changes by 50 degrees -- to 80F (the next afternoon). By *your*
numbers, expect a 10% change in tire pressures: 41.8/39.6
The problem is the naive "+3" that the tire monkey uses to bias the
"hot" temperature of the tire. He's factoring in a ~10% increase even
though the tires *probably* haven't risen 50 degrees in the 2 miles from
our home to the store over *cold* asphalt.
E.g., car claims it is 67F in the garage, now. It's been sitting there for
at least 6 hours. TPMS claims 38/36 as current pressures.
Tomorrow AM we'll expect 50 for a low -- with a high of 60. Saturday morning,
we'll touch freezing (we've already been down to 21). Last month, we were
seeing 80. Temperatures around town vary by ~10F (currently, 48-56F).
When we purchased the car, it was 110F. So, sitting in the garage these
past four months, the car experiences an 90F swing in temperatures -- before
rolling friction is taken into account.
Pick an inflation pressure. Then, expect to change it pretty regularly
(or live with under/overinflated tires in SOME set of conditions).
No big deal. I virtually ALWAYS over-inflate my tires according to the
placard. by at least 10% (at 70 degree F nominal temps)
My tires see temp swings of up to 130F degrees (or even slightly more)
over the year, not taking into account the heat buildup from driving
We *add* because I *bleed* off the excess pressure. Ambient has changed
~60F in the past 4 weeks.
As I stated elsewhere, TPMS claims tires are presently at 38/36 at 67F,
sitting in the garage for 6 hours (51F outside). In a few days, we'll be
at freezing when SWMBO heads off for an early morning class. A few
of weeks ago, 80 degrees in the afternoon. Two weeks ago, 21-24 at night.
In another couple of weeks, 80 will be the norm, again. Then, +10F every
month until we're at 110.
When the pressures are "in your face" (on the dash), you're less likely
to ignore those low *or* high pressures (than you would, otherwise, if
you had to manually check pressures!).
So, you pick a temperature and a pressure and *hope* the weather
stays reasonably constant. As all *I* can do is bleed pressure from
the tires, I have to rely on Costco to put it back in when the
temperatures fall (again).
I'd have it filled about 2 lb over the recommendation and just leave it.
I don't see the pressure unless I turn the screen t that page or if
there is a low warning. Tires have a pretty reasonable tolerance. No
sense going nuts over it
We've never had a warning indicated. Instead, SWMBO started exploring the
various displays on the various screens shortly after purchase (makes sense
to familiarize yourself with a new vehicle). She then became fixated on
that display when she noticed the one tire losing pressure (i.e., she made
a point of checking it each day and noting that it didn't "track" the
There are three screens/displays in the car. The one that shows tire
pressures shows very little else of interest -- the various odometers,
oil life, instantaneous fuel economy (also available on one of the other
screens), average speed/hours driven (on this tank of gas), etc.
It also shows some *dynamic* displays -- e.g., if you alter the
volume, channel, etc. on the sound system, that is displayed
briefly, overriding what would otherwise be displayed. I think
there is an option that allows the driving directions to appear
there ("turn left", "turn right", etc.). And, the lane departure
warning system uses it (we didn't opt to purchase that "toy").
It's much easier to keep the tire pressures "consistent" in the
non-winter months as the temperatures tend to vary less.
How consistent do you expect it to be? Both front tires are the same,
both rear tires are the same, but are 2 psi higher than the front.
Close enough for me.
Remind her that 33 and 34 are really very close with rounding. 33.4
will read low and 33.5 will read high. Could drive you nuts trying to
get perfect reading with different temperatures.
Before you had a readout the pressures were probably much worse that
what you see. Put some black tape where the actual readout is.
Came with one of the packages on my car. Once in a while it is
annoying, but other times it is handy. Could be a lifesaver if you were
to doze off. It will steer for me but alarms if you have your hands off
the wheel very long. This is my car
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.