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I'm probably being OC but I live in AZ and check my tire pressure daily before I drive. Not manually but I look on the dash before I drive and usually if I drove it the day before I have seen a drop as low as 27psi which I have confirmed manually with a tire pressure gauge. I filled it back to 30 when I saw it at 27. I know that in cold weather your pressure may drop and in hot weather it increases. As I'm driving the pressure is 30-33. Is it normal for it to fluctuate like this? Again I'm probably being obsessive compulsive for I never tested my tire pressure in other cars but I was a civic driver for the last 20 yrs! I'm not getting a warning that they are too low but just want to make sure this is normal. Thanks.
 

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I think its normal- mine now has nitrogen and is very stable. The weather is hot here and without nitrogen tires here will swing a PSI or 2. cutnout aka Cutnout
 
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Mine goes up 2-3 once hot, I run 2 lbs higher anyway from the sill, guys at conti told me years ago that 2 lbs more than sill gets you 10 pct more life without comfort problems, works for me.
 

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I have noticed on all of my vehicles with TPM that setting in the sun will warm the tires a lb or two in those tires that have the sun shining on them. they will equalize after several miles of driving.

Also, I do not think the tire pressure check before you drive is very accurate. You should drive a few blocks to get an update from the sensors.
 

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Aliens are beaming Gamma Rays at your tires...wrap them in tin foil at night :confused:

Seriously, I have noticed a 2-3 psi change cold to hot
 

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Once again the mis-information the nitrogen doesn't change pressure with temperature is proven wrong.
Agree, although nitrogen has a couple benefits, they are very small and certainly not worth the cost in car tires. Aircraft use of it on the other hand is very beneficial. Oxygen burns, nitrogen doesn't and it's also less corrosive to rubber and typically the magnesium wheels used on most aircraft.

The air we breathe is made up of 78 percent nitrogen and 21 percent oxygen, I would say that's close enough!

Kurt
 

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I'm probably being OC but I live in AZ and check my tire pressure daily before I drive. Not manually but I look on the dash before I drive and usually if I drove it the day before I have seen a drop as low as 27psi which I have confirmed manually with a tire pressure gauge. I filled it back to 30 when I saw it at 27. I know that in cold weather your pressure may drop and in hot weather it increases. As I'm driving the pressure is 30-33. Is it normal for it to fluctuate like this? Again I'm probably being obsessive compulsive for I never tested my tire pressure in other cars but I was a civic driver for the last 20 yrs! I'm not getting a warning that they are too low but just want to make sure this is normal. Thanks.
Tire pressure will change about 1 psi for every 10 deg F change in temp. A fellow who tracks starts at 26 psi and indicates on the track it reaches 36 psi. After riding for a while, when you stop, reach down, and feel the tires. They are warm! Take a lot of sharp turns and they are hot! With my normal driving they start at 29 psi and reach 32 in about 10 miles (this time of year.)
 

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Hey guys, I was a tire store owner for 30+ years. The tire pressure monitors were a constant source of aggravation. They often would read low or high. They are ultra sensitive. But yes for sure tire pressures change several times a day. Especially when we have hot days and cool nights or changes is seasons. Always check the tires when they are cool but don't get to excited if they vary 10% or less. But also as stated above, the monitors tend to be more accurate after they have been in motion. However the air has also heated and may show a bit high...

Now, Nitrogen fill is the only way to go. It is typically very stable so pressures usually do not fluctuate. Keeps the tire running cooler and the wheel is less likely to have a "crud" build up around the bead seat area as well. So while a pressure check via monitor is a good idea, using the old fashion air pressure gauge against a suspected problem reading is the best way to double check. Then remember the monitors are there more to alert you to a potential problem, (slow leak) but they are not always consistent in their readings. Typically we found those tires that did not actually have a pressure problem, that the monitor would return to a normal reading in a day or two.

Happy Motoring!
 

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Agree, although nitrogen has a couple benefits, they are very small and certainly not worth the cost in car tires. Aircraft use of it on the other hand is very beneficial. Oxygen burns, nitrogen doesn't and it's also less corrosive to rubber and typically the magnesium wheels used on most aircraft.

The air we breathe is made up of 78 percent nitrogen and 21 percent oxygen, I would say that's close enough!

Kurt
Agree. There was another interesting reason for using it in aircraft. They fill the shocks with 1500 psi nitrogen, as I recall. That leaves a lot in the high pressure cylinder when the pressure gets that low and can no longer be used to fill shocks. They use the remainder in the tank (1500 to ~ 200psi) to fill tires (or at least that was done in the past!)
 

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I'm no expert on nitrogen versus air inflation, but I've been getting my Vette tires installed at Tire Rack (located here in Northern Indiana) since buying my first Vette, and I consider them to be experts on most things tire and wheel related.

Here are their thoughts on the matter:

- Nitrogen is a gas and is still affected by changes in ambient temperature (about one psi for every 10° Fahrenheit). Nitrogen filled tires will require pressure be added during the fall/winter months as ambient temperatures and tire pressures drop. Nitrogen is good but can't change the laws of physics.
- Nitrogen reduces the loss of tire pressure due to permeation through rubber over time by about 1/3. This helps maintain the vehicle's required tire pressures a little longer, but doesn’t eliminate the need for monthly tire pressure checks. This is good for people who don’t maintain their vehicles well.
- Nitrogen is non-corrosive and will reduce oxidation and rust due to the absence of oxygen and moisture. This will help minimize wheel corrosion to promote better bead sealing. Tires that are used routinely will be replaced long before any life benefit would be received by using Nitrogen. This is most beneficial for drivers who drive their vehicles infrequently (car collectors, track drivers, snow tire users, motor home owners, etc).
- Nitrogen is a dry gas and will not support moisture that could contribute to corrosion of the tire’s steel components (bead, sidewall reinforcement and belts) due to the absence of moisture over extended periods of time. However it’s important to remember that atmospheric pressure is constantly pushing oxygen and moisture into the rubber from the outside of the tire. This is especially good for low mileage drivers who don't wear out their tires quickly or those that run average annual mileages but use long wearing radial (60K and 80K warranted) tires.
- Nitrogen assures more consistent pressure increases due to increases in operating temperatures in a racing environment because of the absence of moisture. This is especially good for participants in track days, high-performance drivers education schools and road racing.
- Drivers should use standard air if pressure adjustments are required when a local source of nitrogen can’t be found during a trip. While this reduces the benefit of higher nitrogen content, it is far better than running the tires underinflated in search of a source. Often the original nitrogen provider will refill the tires for free or a nominal cost when the driver returns to his hometown.

Tire Rack - Tire Tech - Nitrogen
 

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Thanks Mobius--good stuff. cutnout aka Charlie
 
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certainly nitrogen has it's small advantages, now you just have to decide if the added charge from the dealer is worth it...if it's anything other than "free" I'm not a buyer, besides as time goes on, I'm gonna put in air as I'm not about to go back to the dealer for more nitrogen...

I can tell you how this came about...dealers have always sold add-ons, but once the public started to beat the dealer down in profit due to internet/truecar/edmunds pricing and screaming "I want invoice" the dealer started looking for other ways to generate gross once they were forced to go near invoice - so out came the add ons:

nitrogen
window VIN etching
protection packages galore: paint, interior, Ceramoglass, etc
tire insurance ( the only real valid one for some)
still the rustproofing game
doc fees
adding minor accessories to every car - wheels caps, pinstripe, splash guards, etc
some fancy F&I plans
and many more you can think of...now these "schemes" are not really fakes, they all work, but not for the 400% markup the dealer wants...

seen last week while I was working in a BMW dealership, price was $799 - no polishing:
 

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The lower moisture content in nitrogen also prolongs the tire pressure sensor's life. I found out the hard way when the sensors in my Infiniti started faulting at 40-60K miles. All were visibly corroded from moisture in the tires.


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For both the C5 and the C6, and for my 2012 Cruze, the tire pressure system only gives a "warning" when the PSI drops to 25 PSI. Can anyone confirm this for the C7 please?

Also, on both our C5 and our C6, the TPMS was off one pound in just one corner. After doing a lot of measuring, using my really good tire pressure gauge to confirm, a gauge which measures down to 0.1 PSI, learned to ignore that corner always being one PSI difference.
 
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