: Anyone else losing tire pressure?



Life.Is.Good.
11-17-10, 12:12 PM
I have a SRX with 3000 miles on it. One month after getting it tire pressure was down to 30 on each tire. Dealership said nothing was wrong and filled the tires.
Now a month later, pressure is at 30 on 3 tires and 29 on the 4th.

Dealership just told me it was normal because cold weather has arrived. I strongly disagreed. If that's true, I would have noticed that on my previous 8 vehicles with tire pressure monitoring.

They're going to check them again for leaks. I'm wondering if all 4 wheels could be bad? I have SRX Lux with standard aluminum wheels.

Thanks.

Ponyman
11-17-10, 12:29 PM
Only loss I have had is associated with the cooler weather, and they only lost about 3 pounds each.

PJ1520
11-17-10, 12:38 PM
Probably normal psi loss. Just keep an eye on it for a month, and expect the psi might drop again with the continued falling temps.

With alloys over the past 25 years I always have lost a little psi over time and mileage, more so than with steel prior to that. There always seems to be one tire/alloy wheel that loses a little more than the other 3. And yes, I lose a couple of pounds due to the temperature drop.

I currently drive a 2004 G35 Infinity Coupe and a 2007 SRX4 N*. Had to adjust the tire pressure upward in both during the past month with the overnight temps dropping into the 30s and only reaching 50 during the day. Like you, I have lost about 2-3 psi per tire, just enough to trigger the TPM in both vehicles when cold and then the TPM goes off while driving.

PJ

TRMN8R1
11-17-10, 12:50 PM
True, drop in temp equates to drop in pressure. However, once you start driving the vehicle, you should see the psi's increase, do you? And, if you drive it long enough, the heat that's generated in the tires should bring the pressures back up to nearly the pressures they were originally set. Where I live here in the NE (Buffalo area), it's not uncommon for me to have to add air during the winter months because the tires just start out at a lower pressure each morning that's it's cold which is pretty much every day. BUT, don't need to add air but once or twice the season just to maintain proper pressures. Hope this helps!

algiorda
11-17-10, 01:22 PM
The only way to stop PSI loss during the winter is to fill your tires with Nitrogen:

"Most tires are filled with compressed air, which when dry consists of about 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases by volume. Water vapor (humidity) can make up as much as 5 percent of the volume of air under worst-case conditions. Filling your tires with nitrogen mainly does two things: it eliminates moisture, and it replaces skinny oxygen molecules with fat nitrogen molecules, reducing the rate at which compressed gas diffuses through porous tire walls. That means, theoretically at least, that a tire filled with nitrogen retains optimal pressure longer, leading to more uniform tire wear and better gas mileage. The commonly quoted figure is that tires inflated to 32 psi get 3 percent better mileage than at 24 psi. "

PJ1520
11-17-10, 02:04 PM
Good info re the nitrogen and the fuel mileage improvement with that additional psi due to the lower rolling resistance, algiorda !!! Thank you for this info. !

I always wondered about the pothole factor for those of us who live in snow country. Banging through those holes certainly might break the seal between the tire and the rim, even if the rim remains undamaged. Worse, the rims might get bent, even ever so slightly. They might even have an edge break off. And that can't be good trying to keep all of the air or nitrogen where it belongs.

In my neck of the woods, road repair and resurfacing seems to begin when the last round ends, never ending year round. Within 6 miles of my house there is a stretch of heavily travelled highway where about 2-3 times per Winter an imperfection in the roadway quickly becomes a cavernous pothole in short order. Picture cars travelling at 60mph and hitting that hole which grows larger and deeper with each car that hits it.

It is not uncommon on this stretch of road for there to be episodes of mass tire blowouts, with 15-30 cars stranded by the side of the road with flats and bent/broken rims, accidents, bent/broken suspension parts, another traffic jam, and then the arrival of a convoy of State Police and tow trucks.

Usually belatedly, either the state or local highway crews show up, close down a lane or two, and then proceed to make repairs.....but by then the damage has been done. One finds oneself changing a tire and operating on a donut and facing the out of poxket expense for a tire replacement and rim repair, if not a replacement of both. Something like this is not covered by insurance, at least not the deductible part. Some optimistic/angry folks try to go after the locale for damages, and once in a while they are successful if they can prove the pothole was reported and no action within a reasonable time frame was taken to fix the pothole before the carnage began.

So I would not be surprised if any of us have, unbeknownst to us, a slightly out of round rim and/or a slight rim leak. Sometimes the leak can be mitigated by simply deflating, cleaning the rim, and then remounting the tire. And sometimes truing of the rim is necessary.

The rim shop I use specializes in alloys and never seem to run out of customers, especially in the Winter and early Spring. They are not cheap ($150-$250 per rim repair, depending upon the severity of the damage), but they are good at what they do and the rim comes out looking like new.

Beats the alternative when I hit a pothole at highway spped or the wifey scrapes a rim on a curb, and we want the unsightly scrape or the leak to go away.......the oem "factory replacement" rims on my wife's Infinity run $880 each.

PJ

sube5186
11-17-10, 02:16 PM
I was having the exact same problem with all four tires, and it WAS NOT weather related. I decided to check the tire valve cores in the stems. All of them needed to be tightened. One was very loose. I already had a valve tool like the one below, so tightening then was not a problem. Pressure seems to be holding fine now.

I have noticed that if you rely solely on the tire pressure display in the DIC, you have to wait until you've been driving for a few miles before it displays accurately. I always check my tire pressure using a good analogue gauge. That's the only way to know for sure if your tires are losing pressure.

If you continue to have this problem, there is a Technical Service Bulletin related to leaking cast aluminum wheels. It affects all GM vehicles. The fix requires resealing the wheel to correct the porosity. The TSB no. is 05-03-10-003F.

http://www.amazon.com/Milton-S445-Valve-Tool/dp/B000COMXGS/ref=sr_1_fkmr0_2?ie=UTF8&qid=1290020410&sr=1-2-fkmr0


Sube

Life.Is.Good.
11-17-10, 02:27 PM
Thanks everyone.
While driving, the highest I've seen the pressure is up to 32.

I've been watching it fall the past month, pretty steady. That's why I don't believe the cold has that much to do with it. Now that it's down to 29 and 30 I want it checked again. Don't want to mess with the tire tread or gas mileage.

Thanks again. I'll for sure have them check the valves.

sube5186
11-17-10, 02:37 PM
Don't forget, you have an air compressor in the back cargo area under the floor. It dispenses plain air, as well as tire sealant. Before you waste a trip to the dealer, I would suggest you inflate your tires to the recommended pressure, check them with a separate pressure gauge and then monitor them over the next week or so.


Sube

Life.Is.Good.
11-17-10, 02:54 PM
I do?? Is compressor standard?

It's no problem. Our dealership brings me a car to drive, fixes my vehicle, then returns my vehicle. My aux plugs aren't working so they are picking it up anyway.

They even bring us a car for oil changes. That's what we get for being their number one customer; 40 company cars + quite a few personal cars.

sube5186
11-17-10, 04:06 PM
I do?? Is compressor standard?

Yelp. That's what they give us, since we don't get a spare tire.


Sube

RippyPartsDept
11-17-10, 04:11 PM
we just got a nitrogen machine... $40 and you're all set... takes about 15 minutes

dctex99
11-18-10, 10:50 PM
also when it rains, or snow is melting, tires lose pressure around the rim....I think tire monitors have just made us watch it more carefully; I see older cars with low tires every day; they should be checked monthly!!

C&C
11-19-10, 06:19 AM
Nitrogen, unless you're getting it gratus (for free) is a waste of money for the most part. I direct you to here for more than you wanted to know about nitrogen and tires: http://home.comcast.net/~prestondrake/N2_for_tires_FAQ.htm

RippyPartsDept
11-19-10, 08:39 AM
What kind of source is that?

PJ1520
11-19-10, 09:39 AM
Rippy......I have to agree with C&C. From a practical or measurable matter, what does the $40 for nitrogen-filled tires get you? I put nitrogen in the same category with aftermarket air intake boxes/filters. I'd rather spenf the money on something else. :beer:

PJ

RippyPartsDept
11-19-10, 10:28 AM
i'm not saying it's a must, but if it keeps the tires at a steady pressure then it's a good thing

now that TPMS can read the pressure in real time through the dash many customers get worried when they see the pressure change

and of course if you don't have TPMS you should be regularly checking your pressure no matter what you fill the tire with

Smokin' SRX
11-19-10, 10:44 AM
Good info all. I too feel Nitro is a waste of $. But, yes, you might loose air a tiny bit slower with Nitro, thus avoiding running w/ low air for a few days, but you still have to check monthly (either manually with tire guage or look at Info display on dash.) Your call.

The SRX sensors won't light up till you're already down to around 29LBS! Both dangerous at speed and horrible wear/MPG, by then. Some ignore the sensor light in the cold mornings, as the rising pressure will put out the light as you drive and heat up the tire, but don't do it. Common for pressure to drop 1lb for every 10F degrees of temp decrease. So, 36 lbs @ 80F, COLD tire, (as spec requires) becomes 31 lbs @ 30F temp. ( that happens within same month sometimes!)

All rims loose air. Especially alloys. How often is the question. Once a week, 5 lbs, is a problem. Great idea to check the valve stem core tightness as SUBE suggests! Any shop can do it in 60 seconds. Some folks say they never added air, but don't realize that their Dealer/shop is correcting pressure w/ every oil change or service. Running just 5lbs low is both dangerous, (blowouts) and costly at speeds above 45MPH.

I have seen my MPG IMPROVE from 21MPG to 26 MPG (highway) just by airing-up to 38PSI. (2 lbs above factory specs!) from the usual, below-spec that I run (33lbs cold). I run the 33lbs (cold) for a softer everyday ride, on my 20's and say damn the gas and extra minimal wear. It goes up to 36lbs as I drive. Ride is rougher @ 38psi, and tire wear is slightly higher down the middle tread, but on long, smooth, summer, highway trips, I didn't care. Especially the way my tires wear extra on edges, from my rapid cornering habits. Not a good idea in snow/ice to run below the 36lbs, cold, recco by GM. Traction losses will occur in snow, and these ain't exactly no snow tires they gave us!

Yes, I'm anal about tire pressure and have a rapid fill air tank in my garage, so no biggie to play with tires weekly, for me. But I would not PAY for Nitro in my tires. For free.......sure! :cool:

SS

PJ1520
11-19-10, 11:35 AM
Smokin.....your post should be required reading. And for that compliment from me, you should buy the first round with the money we save on skipping the nitrogen. :drink2:

I would like to add something here and would like input from others.

The psi on the SRX DIC readouts (driven by the TPMS sensors) do not match the gauges at my service station, neither the one on their air hose nor the analog manual one they pass between mechanics. Nor do the DIC readouts match my digital gauge. They don't match my expensive analog gauge. And they don't match the analog gauge on my electric tire pump. All three of my gauges are in agreement with one another.

I wrote off the service station gauges because they are used to death and are abused. Both my digital gauge and my analog gauge agree with one another....but both never match the SRX DIC, off by about +- 2 pounds, up or down, depending on which tire I am checking.

I trust my own gauges over the DIC for accuracy. One reason is that all three of my gauges don't take a pounding like the TPMS sensors do. And the second is that all three of my gauges will read exactly the same pressure for the fronts, for example, while the DIC reads higher for the left front and lower for the right front. Something is amiss. So I treat the DIC as a relative reference point, not an accurate reading.

Another thing I need clarification on. Does the TPMS warning activate on a particular tire that is out of wack with the other 3, by a low readout threshold triggered by one or more of the tires, or when all/most of the tires in general are low by a certain psi variance % or poundage?

Is it possible through the relearn procedure to bring the TPMS readouts in sync with my gauges? It is a real pain to look at the DIC readouts and have know that when it says 28psi for the right front that there is actually 30psi in there. And if the left front is reading 32psi there is actually only 30 in there. No consistency across the board from tire position to tire position, up and down.

Now that I have put everyone to sleep......hopefully you folks can enlighten me.

PJ

Smokin' SRX
11-19-10, 11:56 AM
Ok............pick the "water hole"! LOL

Simple answer: All TPMS are "Off" by a pound or two. Even Lexi! They were essentially developed to show a dangerously low tire pressure BEFORE the blowout occurs, on a long highway trip or just warn you first thing in the morning, that you have a slow leak and are already down to 19PSI before you take off. Nature of the beast, from every car mag I've read.

Some autos have a General indication that one tire is low, based on it's individual pressure, but won't say which one (Recent Malibu I drove had this type). You gotta get out and check.

Ours, as we know, has individual point monitoring, with the criteria also again being, individual pressure, irrelevant to other tires or rate of loss. Relearning the sensors doesn't affect.



Way better than nothing............I use my digital as a real reading, too.

SS

RippyPartsDept
11-19-10, 12:58 PM
I've got those valve stem caps that pop up when the pressure is 32psi and have a green ring (for good pressure i guess) - and a 32 on the top... i've yet to see how accurate they are, but they seem pretty good

PJ1520
11-19-10, 02:32 PM
Ok............pick the "water hole"! LOL

Simple answer: All TPMS are "Off" by a pound or two. Even Lexi! They were essentially developed to show a dangerously low tire pressure BEFORE the blowout occurs, on a long highway trip or just warn you first thing in the morning, that you have a slow leak and are already down to 19PSI before you take off. Nature of the beast, from every car mag I've read.

Some autos have a General indication that one tire is low, based on it's individual pressure, but won't say which one (Recent Malibu I drove had this type). You gotta get out and check.

Ours, as we know, has individual point monitoring, with the criteria also again being, individual pressure, irrelevant to other tires or rate of loss. Relearning the sensors doesn't affect.

Way better than nothing............I use my digital as a real reading, too.

SS

Good stuff!

By the way, are you sure you would permit yourself to be seen with someone still driving a Gen I SRX? ;)

Smokin' SRX
11-20-10, 10:42 AM
PJ, You may not know that I had a First Gen SRX, N*, loaded, AWD, Mag Suspension, full glass roof, and all! (just no DVD/3rd row option). That was origin of "Smokin' SRX" name. It flew, with that 320 HP V-8 ! I was on this forum from 2004-2007, when I got a new 2008 Enclave........but I'm back! LOL

I wrote volumes about switching all 4 tires to same size in 2006 (as opposed to diff front/rear from GM) Much concern/opinions by all. In the end, very successfull experiment. (went fatter rear tire size all way around!) And yes, I turned heads everywhere we went with the black diamond paint, chrome wheels (aftermarket option) and unique styling that you still enjoy :}

Guess I know u well enough for a Capt. Morgan, based on our common lineage. LOL

TheCaptain
11-20-10, 07:31 PM
I would like to add while my 20"ers were on, i was losing about 1-3 psi in each tire per month regardless of temperature or kms driven. My 18"s seem to be holding so far.

Also, don't forget, our tire monitor is only accurate if someone has reset the monitor (in the event of rotated tires) because the monitor won't follow the sensor. You have to reset every time you move a tire (from one spot to another) so that the monitor represents the proper tire.

PJ1520
11-21-10, 12:31 AM
I propose we start a chapter of of AA.............Anals Anonymous. My wife thinks I ponder this type of stuff way too much.

Smokin' SRX
11-23-10, 12:51 AM
so does mine. Then I point to all her pocket books and shoes.....

SS

jcapps
11-25-10, 03:54 PM
My tires are constantly losing pressure. It has to go to the dealer due to a check engine light. I am sure the dealer will tell me thats normal. Never went through this with any other vehicle.

Smokin' SRX
11-28-10, 11:29 AM
My tires are constantly losing pressure. It has to go to the dealer due to a check engine light. I am sure the dealer will tell me thats normal. Never went through this with any other vehicle.


I don't see what size tires you have in your Profile/Info ..........but, I can tell you that 20" low profile tires and alloy rims are a formula for slow air leak. Very common on Muscle car forums.... don't despair. Not that it helps us, but nature of beast me thinks.

we should all list some basic data on our Profile/info line EG..., .model, main options

SS

jcapps
11-28-10, 09:32 PM
18" wheels. My z06 has not lost a lb since I last checked, my collector cares either.

carbdude
11-30-10, 11:39 AM
OURS LOOSES AIR CONSTANTLY ALSO!

I've had to top off our tires every 3 or 4 weeks since purchased in May (were now @ 5,000 miles).

I use a High Dollar Racing Tire Gauge so I know it is highly accurate @ 35lbs....
But the DIC always shows 30-31 lbs... 4 to 5 lbs off WTF?

Another Item On The Dealers Look @ List.

18" wheels - Lux. Pkg.

Dude

Smokin' SRX
11-30-10, 08:35 PM
18" wheels. My z06 has not lost a lb since I last checked, my collector cares either.

Thx JCapps. Sorry, no other ideas. but it's fairly common with alloys. The 18" seem impervious. Love the uni-directional on the Vette. That's a sweet ride.

SS