Hey folks, with the weather starting to get cooler in many parts of the country, I thought this would be a good time to remind everyone about the tire pressure monitoring system (especially since I got a TPMS light this morning).

On cool mornings, you may get a TPMS light -- this is because the air in the tires is cooler and thus under lower pressure. This is also a good time to check the pressure in your tires, since the stated pressure (don't have my manual handy) should be set when the tires are cold.

Edit: I hate to sticky my own thread, but someone else suggested it, so I'll do it temporarily.

 

If your stock tire pressure is set to 32 PSI cold as specified in the door jam and manual, the TPMS light should not be coming on.

It should only come on if the pressure is less than 26 or higher than 49 PSI.

rx8cited

 

This is a good idea. Should be a sticky. Mine came on this morning as well.

 

You should always seasonally adjust the tire pressure in your tires - the rated pressure is for current AMBIENT air, and the tire will drop about 1 lb of pressure for every 10 degree drop in temp. I check mine monthly in the morning before a drive and make sure the day i do the check, it's an average day for that time of year. Then I adjust from there.

Best thing to invest in is a high-quality pressure guage.

 

Mine came on to about three or four mornings ago. That was the reminder I needed

 

This is good to know so I don't get surprised on a sunny December day! About two more weeks and this will be a weekend car. (If it is sunny).

 

I finally checked my tires this morning (after an overnight low of 42°F for the third night in a row), and they were all at about 26psi cold. So I inflated them all to 32psi before heading out this morning.

 

Beware, I went up to Tahoe last week (7000 ft.), from sea level. When I got up there, my light came on also. Tires looked fine, I talked to my brother-in-law, who is a real car expert. He said not to worry, the altitude caused the pressure to increase to the point the TPMS came on. He stated it would go off when I went back down to L.A. Like a dumd ***, I trusted him, and drove 500 miles back home. When I got into L.A., the light was still on. I checked the pressure, and one tire was about 25 psi. What a fool.

Don't trust why you think it comes on, check your pressure.

 

I was under the understanding that the system was designed with a high and low pressure as well as a differential pressure. The high and low were mentioned but I was also told that if the pressure in any of the tires varied more than 4 psi it would come on as well. That true?

 

Who told you? I've never heard or read this, so I don't have any reason to believe it's true.

rx8cited

 

--Mazda master mechanic at Laird Noller Mazda in Kansas City. He was going over sytems in the car with me after we brought the car in for him to trouble shoot the check engine light.

 

Mine came on this morning, scared me to death. Walked around the car in the pooring rain looking for a slashed tire and thankfully didn't fine one.

 

haha, it sounds to me like you did what i did. I'm a few miles away from my oil change and i live on a hill..so i turn the car on this morning and i have the oil light AND the tire light..i jump out to look for tires with holes and such and then remembered this thread..i haven't actualy checked the tire pressure yet--but due to the fact that my hands are numb from being outside for 10 min..i'm really not to worried that it is low. (but now that i said that, they'll all be low!)

 

I love watching Floridians try to deal with 70 degree weather.

 

Did she say her hands got numb.....I wonder the temperature was.... :D

 

Simply Blue: Arent you supposed to be working, Buddy?

 

Oops. Just found the thread where she says it's 56 out.

 

it was 49 all night people...and that is cold...there is a huge diff. between winter here and winter up north...but thats not a topic for this thread..:D

but after driving and letting the temp get into the 70's, my TPMS went off...even though my TP was 26 in the rear two...stupid air

 

I second this. I am a car newbie (read: computer geek). I bought a tire pressure guage for 89 cents at walmart and it sucks! haha. It doesn't even give repeatable readings! I can't believe I spent 89 cents on it.. man I feel ripped off.

 

OK, let's do a little math here. Your sea level pressure is at 14.7 psia. So, assuming Tahoe at 7000 feet is under a tight vacuum, the most your tire pressure will be (assuming you pumped it up to 32 psig and Tahoe is colder than LA) is 46.7 psig. Your lights snap on at 49 psig.

I hate to pile on, but you were right about the fool part.

 

^^confused the hell out of me

 

I got my car during the summer and the light came on only once... and yes the tire was low in pressure. In the last few days it would come on every morning and it started with a significant temperature drop... so I too thought that lower temperature resulted in lower tire pressure so I was not too woried... After a while I was driving the light would go off probably because the friction heated the air up inside the tire... anyhow I will go to fill 'em up asap.

 

Last night I left my house and drove a short distance before my tire pressure warning light came on. I realized I didn't have a tire gauge with me so I pulled into the first gas station I came to and purchased one. I don't know how accurate it is, but all 4 tires checked out at 30 PSI, I looked inside the door at the label that should tell me what the correct pressure for the tires is, but guess what? It didn't have this information printed on it! It of course has the spaces for the recommended PSI, but the numbers aren't there.

Anyway, since I didn't know what the tire pressure should be, or how accurate the gauge was (really cheap one), but since they were all the same I just started driving again. The light came back on when I started the car and stayed on until I shut it off at my destination. I was out of the car for no more than 5 minutes and when I restarted it the light stayed off. I made one more stop before heading home and the light never came back on.

Now I noticed after getting my car that sometimes the bluetooth headset I use with my cell phone acts a bit odd when I use it in the car, not every time, but just some times. I also know that the tire pressure sensors use radio waves to transmit the information they gather to the car, is it possible that there is some sort of interference happening between these?

Also, why the heck aren't the recommended tire PSI's listed on the label on the dorr frame? What's up with that?

 

I can't answer your question about about the cell phone but the tire pressure should be set at 32 psi, remember that in cold weather your sensors may trigger the light and after you drive a bit and warm them up the pressure will return to "normal" .

 

There's another sticker on the suicide door with the information printed on it (at least there is on mine)... I don't know why they did it that way. 32 PSI is the recommended pressure I believe... after you started driving you probably warmed them up and got them to the proper range. My light has only gone on once, when the temps dropped quite a bit, and one of the tires was ~27psi, with the others around 30.