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.
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 overinflated.
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.
I had the same thing over New Years. The little screen with the odometer kept running a message to check tire pressure. The tire shaped orange thing on another part of the instrument panel wasn't enough warning. It was several weeks since I drove my Frontier. All four were a bit low. Aluminum wheels can also cause pressure loss. I guess the aluminum oxidizes breaking the tight seal between tire and rim. I've had it happen a couple times on my car.
If you are getting that kind of pressure change they are NOT using nitrogen
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.
The rims I have the studs mounted on don't have the sensors so the yellow light is on all winter. I find it very easy to ignore, but if it really bothers you try about 1/2" of electrical tape.
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.
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 have to.
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 light on.
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).
A *leak* would show LOW pressures, not *high*! I am continually bleeding pressure from the tires as the "few" cold mornings are the exceptions yet the tire monkeys plan on them as the *norm*.
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).
Yeah I use that 80% stuff too and I have a machine in my garage that seems to make it virtually for free I seldom have to add air unless I have a (problem) leak. One thing about my wife's Lincoln is that sensor does not turn off right away, you have to drive a little ways. Trust your gauge.
I dont know where those sensors are located or how they connect from a rotating tire to a wire???? I never had a car with them, and hope not to ever have one. Just sounds like more worthless shit to cause problems.
However, I'd guess that wherever they connect to a wire, you can probably just ground the wire to turn off the light.
They can be quite handy to have. Tires, especially low profile don't always tell you the actual pressure from appearance and I don't know anyone that checks with a gauge every day. I had one go off on my last car so I added some air. Next day, the tire did not look low, but it was. The light tipped my off. Rather than put in more air I went to the tire guy and he pulled out a big nail.
Part of the problem is a lot those TPMS were calibrated to come on just below the max cold pressure on the OEM TIRES, not below what was on the B-pillar auto mfg sticker, which is where I keep my tires about 2lbs psi above.
Of course, in this enlightened age second decade of the new millennium, you'd think both mfgs and mechanics would know better, but no. Now I have ASE Certified technicians telling me, on newsgroups like this, and in person, to go by the cold inflation pressure on the basketba- I mean - TIRES. That the B-pillar door sticker pressures are "too low". Who knows more about how a specific model car will be driven - the tire co. or the car co.?!
Needless to say I never let any tech or mechanic TOUCH my tire pressures, or my wife's except when having new tires put on.
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