TriniBwoy

For the past week now we've been getting some cold weather. Every morning when i start the car, the TPMS warning lights up for the two front tires. The funny thing is that the readings for all four tires is about 28PSI (according to the MID). I always take a quick glance at it and it looks fine (the front two that is). Now what I do is pretty much ignore it because after driving around for a while the warning light goes away. Could the TPMS just not perform correctly under cold conditions?

Desert_TL

The ideal gas law states that pressure is directly proportional to temperature if the amount of gas (i.e. number of moles) and volume inside the tire remain the same:

pV=nRT where p=pressure, V=volume, n=number of moles of gas, R=gas constant, and T=temperature in kelvins.

Therefore, when your tires are very cold, like when you first start your car in the morning, the pressure will read lower by the TPMS. However, after you've been driving for a few minutes, the tires become significantly warmer due to heat imparted on the tires by road friction and sidewall flexing. After the tires warm up, the pressure increases above the threashold that the TPMS considers "low pressure".

In conclusion, your TPMS is functioning properly. Add more air to your tires.

HiTEC

Been in the single digits all week where I'm at and I've never had that problem. I had my car through the entire winter last year, and never saw the problem as well. Sounds to me like you need to check your tire pressure and give them some more air when cold to bring them up to the cold tire pressure.

datmrman

I had this issue a few weeks back. Mine were reading 28s and 27s. I simply added more pressure (32 psi) to the tires and the problem went away.

If you switch to Nitrogen gas, then you can prevent the variations due to temperature.

TriniBwoy

Well professor Desert_TL, I'm not going to add more air to my tires because although it's winter, the temperature fluctuates alot so I don't want to have too much air in the tires. Besides, MID reports safe PSI readings after driving it around a bit.

vc123

haha nice job phyical chem there eh lol

06AM6MT

Just had the same thing happen... got cold (19 yesterday- brr!) pressure dropped to 26 in the rear cold- 28 after a bit of a warm up drive...) .... stopped at the service station and bumped up the pressure.... was happy to have the tpms tell me about it.
Though I can see if the temps in your area spike from 20 to 60 over and over that you might get annoyed the tpms makes it easy to always have the right pressure.

Adjusting the tires take 2 or 3 min at most... It might sound crazy- but I actually use my bike pump when it isn't 19 degrees outside to adjust pressure. Perhaps a bit strange- lol.

leedogg

I would say your front tires are on the borderline low side. Pump them all to 32 when they're cold.

Thorin78

ahh Pv=NRT

PvNERT

Rocket Man

^^ what he said

avs007

That's one way to do it. However, the reason why you are probably getting such fluctuations in your tire pressure, is the moisture content in the air. A lot of places don't bother putting in-line dryers on the lines, nor do they bother to drain their air-tanks...

I've been to gas stations, where when you spray the air, water droplets actually spray out with the air.

That's one of the reasons I bought my own air-compressor. (That and the tools). I put on a line-dryer on my air-hose. I don't get the fluctuations in tire pressure any more.

Pat D

Bad idea. The 32lbs is required when COLD, not warmed up. Always fill tires cold. Even tires backing in the sun or on hot asphalt will give inaccurate readings.

Ernie Golfs

You know if you ignor the low fuel warning long enough, it will stop too. Unfortunatly so will your TL.

Silver Bullet

I agree. The tire pressure should be measured when the tires are cold. Don't know how much that helps when driving in snow, don't you need to lower your pressure to get better traction? What do I know about snow, I live in Texas.

SILVERADO

for every 10 degrees that outside temperature decreases tire pressure will drop one pound. acura calls for 32 lbs when tires are cold so add air as the outside temperature drops.

the number one reason tires blow out is due to heat build up caused by under inflation.

Desert_TL

True that.

A SiQ TL

Same here.

eoswin

Can i have tpms in my acura 06.?? what would be the price?

TriniBwoy

If you have a 2006 TL you already have TPMS.

eoswin

Sorry I forgot to mention it is 06 tsx

fsttyms1

If your tires are that low cold, they are to low psi. Add air to them cold, it will solv your problem and you wont over inflate your tires or have too much in.

jzacuto

Sorry to sound like a simpleton, but isn't the general rule (and isn't this published in Acura tech pubs) to always measure tire pressure when the tires are warm? So if the TPMS is registering low (and you don't appear to have a flat tire) and you drive a bit and the pressures come up, everything's pretty honkey dorey.

TriniBwoy

Yeah, since then I've pump all four to 31/33 PSI and check them regularly (espiecally with a set of Michelin Pilot Sport A/S tires).

TriniBwoy

Not sure...sorry.

6spMike

The rule has always been to check cold.
Add a couple or 3 psi if they are warm; i.e. set to 35 if you want 32 when cold.
You guys got me thinking...
At first thought, nitrogen or dry air shouldn't make and difference in the pressure variation over temperature. pv=nrt is the universal gas law.
On second thought, maybe the vapor pressure of the humidity in the air is the cause of the difference. The water precipitates out when it gets cold (it snows or rains in your tires!), so the vapor pressure contribution from the water drops.
Wow, I learned something today.
Whoo Hoo!!!
Mike

evolpe

You guys are getting way too technical. The people who are saying the tpms is inaccurate in cold and extremely hot climates are wrong, it's always accurate. It's how the temperature affects the pressure inside the tire. However, if you have a warm air pressure reading somewhere around 35 psi, excessive heat will never cause the pressure to reach dangerous heights and vice versa.

mike03a3

I've seen several posts saying you pump them up to 32 cold. The recommended pressures on my '07 TL-S are 35 front and 32 rear. Since the TPMS will go off at 20% below the standard pressure, that's 28 for the fronts. My car was delivered with low pressures. The next morning I got the tire pressure error when I started it. I just pumped them to 35 and 32 and they've been fine since.

It's a basic, albeit annoying, fact of life that we need to check and adjust our tire pressures to compensate for seasonal differences in most parts of the country.

Putting the fronts up to 35 where they belonged also helped the handling.

evolpe

I got mine in december and I live in the north east where we've been having weather all over the place. The dealership couldn't have checked the tire pressure to regulate them because my front right was near 40 and my front left was 30/28 depending on the weather. I first noticed it on a cold day when the TPMS warned me about the front left being low. I was pissed when I saw how fucked up all he pressures were. The dealer owed me a detail so I told him to regulate the air pressure. Moron forgot to tell the service guys so I had to do it myself.

Also, when I did my own detail of the car (dealership details blow) I noticed some nicks in my paint (I bought an 06 demo). Did any of you guys get toch up paint with your purchase? Since they never touched up my car during the detail I'm tempted to go over there and demand they give me a bottle.

007TL-S

SPOT ON BROTHER-MAN!

MisterFubar

iTrader: (1)

I removed the sensors on my old vehicle just for this reason. I got tired of airing my tires down and having to listen to the low tire alarm go off.

jptl04

iTrader: (1)

even if you remove the sensors, the TPS alarm will still go off. i don't think there's a way to disable it. correct me if im wrong.

MisterFubar

iTrader: (1)

This wasn't on my Acura. I removed them on my Nissan Titan. The truck had a little bit different system on it and with the sensors removed the alarm wouldn't sound although the light would eventually come on after the truck was running for around an hour without getting a signal from the sensors.

niti

Can you tell me more about the "line-dryer" apparatus? Where to buy, how much etc. That sounds like a great idea if it's fairly inexpensive. Is it something that you just pick up at home depot? Did a search on the home depot site and came up empty.

jptl04

iTrader: (1)

found this on ebay is this similar to the one you bought?
http://cgi.ebay.com/ebaymotors/AIR-W...QQcmdZViewItem

bumski667

use nitrogen

TriniBwoy

Excuse my ignorance, but what's the benefit of using nitrogen.

Also, the weather has been quite nice these past few days, so now I have a higher PSI reading from MID After driving around on the freeway, the PSI get as high as 37 PSI, does anyone know if this is a dangerous level? Is there some set PSI we should not exceed?

Thanks.

MisterFubar

iTrader: (1)

Here is a quick and dirty answer on why you can use nitrogen.

"Here are a few other benefits of using Nitrogen in tires:

[1] Nitrogen is denser than Oxygen: This means the larger
molecules escape less easily from tires resulting in a more
gradual loss of pressure over time. According to the Michelin
Tire Manual, a tire that is inflated with Nitrogen loses its
pressure 3 times slower than if it were inflated with air.

[2] Nitrogen is moisture free: Pure Nitrogen inflated tires
experience less steel belt and rubber degradation. Nitrogen use
also reduces valve and wheel corrosion.

[3] Nitrogen provides longer tire life: Nitrogen inflated tire
run cooler and require less maintenance according to the Goodyear
application bulletin.

[4] Nitrogen is non-flammable: Nitrogen technology has been used
in aircraft, military and race car technology for over thirty
years."


You should be just fine with 37 psi, it's not enough of a difference to cause any abnormal wear and it's well within the safety limits of the tires. If it bothers you, go ahead and take them back down to your normal pressure for peace of mind.

MisterFubar

iTrader: (1)

*Didn't edit in time*

It's not worth the trouble of running pure nitrogen if you ask me, we have a nitrogen generator at work and if I have a low tire at work I'll go ahead and fill it there, but I won't go out of my way to do it. I've never had a tire that rotted out before the tread was worn down and I've never had a problem with corroding wheels. I bet most shops that sell you nitrogen for your tires are only using nitrogen that's about 95% pure anyway.

fsttyms1

Thats a safe psi. The maximum is printed on the sidewall of the tire. I run mine between 38-42 depending on the driving im going to be doing. And i dont get unusual wear.

mike03a3

Actually, O2 is denser than N2, not the other way around. If anything, the difference is molecular weights slightly favors oxygen.

Maybe, maybe not. Industrial nitrogen is likely to have less water vapor than your basic gas station compressed air, but how much less is a variable. The primary cause of rubber degradation is external exposure to ozone, not internal exposure to O2 or water vapor.

There is no scientific basis for this claim. Properly inflated tires will certainly run cooler than under-inflated tires. It's far more important that you check your tires frequently than it is that you fill them with anything other than air from a compressor that has a drier on it. (A drier that gets maintained!)

Ah yes, the inevitable "it's used by the military and airplanes, it must be better" argument. Airplanes use nitrogen for several reasons. (1) It's basically free. Aircraft use high pressure nitrogen to pressurize the oleo struts in the landing gear, so there is plenty around. Military bases (and I assume large commercial airfields) have LOX plants to produce liquid oxygen and nitrogen. (2) Aircraft grade nitrogen, like aircraft grade oxygen, is exceptionally pure and free from water vapor. Aircraft grade oxygen is better in both regards than hospital grade. This is critically important because aircraft operate systems at extremes of both temperature and pressure. The gas in the tires and struts may be over 100 degrees on the ramp in the summer, but a few minutes later they may be 30 or 40 degrees below freezing at cruising altitude. Any water vapor or impurities could cause serious problems under these conditions.

The other thing to consider is reality.

a) You already have almost 80% nitrogen in your tires. Air is mostly nitrogen.
b) The nitrogen you're buying won't be pure. Often it is only 95% or so, about the best from your typical gas station membrane generator. .
c) When you "fill" your tire with nitrogen, you are starting with a tire that is already full of air unless you use a vacuum pump to suck it all out first. An empty tire contains a volume of air at 1 atmosphere, almost 15 psi. To make your tire gauge read 30 psi, you pump in two more volumes. So, your tire contains about 90% nitrogen, or about 12.5% more than you started with.

Bottom line, for passenger cars it's really just a gimmick to make money.