new owner question Tire Pressure (NYC)

[sp535]

hi all, I am happy new owner of CX-9(Touring 08) and its been quite pleasure drive past 2 month. This morning was brutally cold(New York City) and suddenly I saw warning light for Tire Pressure.

I called service department and told me that it is normal under extreme cold/hot temperature. How could that be true for the cross over vehicle?

Could someone advise what to do?

Thank you in advance.

[jabba]

Dealer said the same thing when we bought ours last week, i.e. in very cold weather the tire pressure light goes on. He didn't have an answer except that he would try putting nitrogen on his demo CX-9.

I personally think the thing is too sensitive, or might be programmed weird...

[clarko]

Aussie models don't get this feature, probably a good thing, yet it would suit our climate better, as there is no extreme cold here LOL

Clarke

[live2ski]

yep, I think it's too sensitive. I get the same false warnings if the temp goes below 10 deg F. I wonder if Nitrogen would help.

[njerald]

Put some air in the tires!!!!!

[todd92]

When the temperature drops, the pressure in the tire goes down. The TPMS is doing exactly what it's supposed to do. You need to put air in your tires.

[live2ski]

yes it drops, but by how much - a couple of psi? the TPMS should not activate this quickly or at least have an adjustment to alert at a lower psi.

[clarko]

Yeh, its kinda like saying " I drive around a lot and my fuel light ends up coming on, what shall I do?" (dunno)

Just tongue in cheek stuff mate! (rlaugh)

[live2ski]

I get it, but my TPMS light is on half the winter. it's not a good sensor if it cries wolf too much.

how about changing you fuel gauge to just a low warning light. wait until it warms up and then you'll have more gas and the light will go out ;)

[jville]

I get it, but my TPMS light is on half the winter. it's not a good sensor if it cries wolf too much.

how about changing you fuel gauge to just a low warning light. wait until it warms up and then you'll have more gas and the light will go out ;)

You'll be crying when you ignore it and ride a tire flat and have to replaceit from a patchable nail.

[jdoering]

I'm not understanding several of the repsonses. The original poster's issue was clear.

Driver's don't expect adjust the air in their tires every few days/weeks. So if an area routinely sees temperations fluctuations of X degrees (maybe 30F?) in the course of a few weeks; then it's important to have a TPMS system that does not trigger within that fluctuation range. Presumably this is safe since auto manufacturers need to design cars to operate within these climate fluctations knowing that most drivers don't adjust their tire pressure weekly.

Given the information about the thresholds and accuracy of the TPMS system; one could calculate the ideal pressure for the tires at a given temperature such that the TPMS will not trigger incorrectly due to the expected temperature fluctuation (assuming that no gas has actually escaped from the tires).

Supposedly N2 would support a wider temperature range; but I don't have any first-hand knowledge of that and there's already a whole thread arguing about N2 versus air ;)

So I think the question is whether anyone has any useful information or firsthand experience with regard to the actual thresholds for the TPMS system; calculating the ideal tire pressure; real improvements experienced with N2; etc. If the thresholds for the TPMS are too tight and cannot be adjusted then it's a design flaw from Mazda; if not then owners just need more tuning information to get their tires adjusted appropriately.

I'll go RTFM and see if there's anything interesting...

-Jeff

[jville]

I'm not understanding several of the repsonses. The original poster's issue was clear.

Driver's don't expect adjust the air in their tires every few days/weeks. So if an area routinely sees temperations fluctuations of X degrees (maybe 30F?) in the course of a few weeks; then it's important to have a TPMS system that does not trigger within that fluctuation range. Presumably this is safe since auto manufacturers need to design cars to operate within these climate fluctations knowing that most drivers don't adjust their tire pressure weekly.

Given the information about the thresholds and accuracy of the TPMS system; one could calculate the ideal pressure for the tires at a given temperature such that the TPMS will not trigger incorrectly due to the expected temperature fluctuation (assuming that no gas has actually escaped from the tires).

Supposedly N2 would support a wider temperature range; but I don't have any first-hand knowledge of that and there's already a whole thread arguing about N2 versus air ;)

So I think the question is whether anyone has any useful information or firsthand experience with regard to the actual thresholds for the TPMS system; calculating the ideal tire pressure; real improvements experienced with N2; etc. If the thresholds for the TPMS are too tight and cannot be adjusted then it's a design flaw from Mazda; if not then owners just need more tuning information to get their tires adjusted appropriately.

I'll go RTFM and see if there's anything interesting...

-Jeff

There is not anything escaping the tires, its the fact that hot air/gas expands and coll it down and it contracts. Every 10degrees F temperature change is equal to 1-4psi change so in your example a 30 degree change is equal to a 12psi pressure fluxuation. Here in FL it was 32degrees yesterday morning and 77 by the afternoon. So lets figure this, a 45degrees temp change is equal to roughly a 5-16psi change. Take 2 minutes out of your life and save yourself a headache and CHECK YOUR TIRES. The warning light is no excuse for poor matainance.

[live2ski]

correct. air is not leaving the tire. the cold temp reduces the pressure enough to set off the TPMS. once the temp increases the tire pressure returns to 'normal' levels and the monitor goes off. I'm not going to add air to the tire just because it's cold out. Unfortunately, I'll probably lose a tire at some point because I ignored the real warning.

[jdoering]

jville; you change your tire pressure daily when you drive in the morning versus the afternoon under such conditions?

Gas expanding and contracting is obvious. The question is how sensitive the TPMS systems is versus how much you can/should over-inflate the tires at higher temperatures to avoid under-inflation at lower temperatures. The real numbers all exist; I don't have them - I was hoping someone might.

Your calculation of up to 16 PSI change from morning to afternoon seems extreme for tires designed to have a PSI of 36. The Mazda service manual cites a change of 1.5 PSI per 18 degrees/F; so more like 2.5 PSI total in your case.

So with those numbers you could just "over-inflate" your tires in the afternoon by 2.5 PSI and probably be fine...

But I'm still curious about the real numbers. Recommended versus Max pressure for the tires; TPMS min threshold; and average pressure reduction rate for N2. The service manual suggests that a dealer can get the TPMS light on threshold (or last value) using the M-MDS.

-Jeff

[jville]

Working an autotech and shop manager, yes i have then checked and adjusted quiet frequently. Twice weekly roughly. jdoering you said its a flaw from mazda? So what you want is an TPMS that doesn't let you know a tire is low until maybe an 18psi difference? so on a 36psi reccomended pressure you would be comfortable riding around on 18psi b4 you were notified about this. The mazda service manual also states how not to rally your car or launch it off ramps. ALWAYS follow the manufacturers rec. pressures unless towing or changing load range. Like i said b4 CHECK YOUR TIRES. they are called idiot lights for a reason.

[kosh2258]

correct. air is not leaving the tire. the cold temp reduces the pressure enough to set off the TPMS. once the temp increases the tire pressure returns to 'normal' levels and the monitor goes off. I'm not going to add air to the tire just because it's cold out. Unfortunately, I'll probably lose a tire at some point because I ignored the real warning.

I live in Minnesota and we recently experienced a temperature swing in excess of 60 degrees within 36 hours and it didn't trip a TPMS warning. In fact, I haven't ever seen a TPMS warning on my 9.

Keep in mind that a TPMS warning can be tripped by only one abnormally low tire. From past experience these systems are rigged to go off if tire pressure goes below or above x% of the nominal pressure.

You'd be doing yourself a favor to at least get the pressures checked to see if you do have one unusually low tire. At worst, you find out if all the pressures are low, at best you find out you have one low tire and save yourself the grief of getting a flat or ruining a tire.

[jdoering]

Working an autotech and shop manager, yes i have then checked and adjusted quiet frequently. Twice weekly roughly. jdoering you said its a flaw from mazda? So what you want is an TPMS that doesn't let you know a tire is low until maybe an 18psi difference? so on a 36psi reccomended pressure you would be comfortable riding around on 18psi b4 you were notified about this. The mazda service manual also states how not to rally your car or launch it off ramps. ALWAYS follow the manufacturers rec. pressures unless towing or changing load range. Like i said b4 CHECK YOUR TIRES. they are called idiot lights for a reason.

Did I mention an 18 PSI difference? Did I say Mazda has a flaw?

Others reported cases where TPMS went off and they did not believe their tires were under-inflated before the temperature dropped. Maybe they were incorrect, maybe not...

Saying "check/inflate your tires" doesn't answer the original questions; that's obvious.

I only said that Mazda has a flaw IF the warning system cannot handle typical daily / weekly temperature swings when the tire pressure is correct for the peak temperature. It's a useless warning if normal day-to-day variation trips it with everything else correct.

Now kosh2258 has come back with useful counter-examples including a suggestion on what might actually triggers the TPMS.

As I've repeated several times; I was hoping someone actually knew something about this. As an autotech; do you actually know how the TPMS monitoring works? I don't need an explanation of how to use idiot lights or that I should maintain my tires per the recommendations.

-Jeff

[jville]

Sry didn;t notice your IF b4. And to answer your question yes i know how the tpms system works. I don;t know how you would want the vehicle to determine the difference between a low tire pressure caused by lower temperatures or caused by a puncture. What if its cold out one morning and you really do get a nail? There are just to many variables to account for. Newer vehicles are having problems because the variant is too low. I must get at least 10 customers on cold days complaining about their TPMS light. And i believe that as of 09 or so they are gunne berequired in all new vehicles. I don't have TPMS on my speed 6, and the lo-pro 18s are hard to tell if low, so i frequently check them. You have to understand my position dealing with dumbasses who come in complaining baout their tires that they ran flat and want me to cover it under road hazard NOT. sry i'm venting.

[jdoering]

Not a problem; I'm an engineering type so my perspective is probably at the opposite end-of-the-spectrum from yours: all theory, actual details be damned :)

I do want to know if my pressure is too low due to temperature; I just hope (like others here) that I can adjust the tires properly for a given time of year and have that be good enough for several weeks irrespective of short-term changes.

Hopefully cars, tires, TPMS, and gas used can combine to achieve a wide enough safe-operating range without false-failures from the monitoring system.

-Jeff

[sp535]

thanks for lots of advices. Please correct if I am understanding incorrectly.

It seems like i need to check tire pressure whether I can find unbalanced condition.

Q1: So, is this something I can do myself? Or should I have to reply on the Mazda service Center?

Q2: I have looked tire pressure gauge from internet and the price and choice range varies too much. Is there any good suggestion based on your experience?

Q3: When default, Does cx-9 have N2 gas or Air inside?

Sorry for too basic questions....
Thanks in advance.

[live2ski]

So i checked my tires. they were all 34psi in a cold garage (40's). I got the car almost 3 months ago and it was in the 70's. Assuming the dealer gave me the car at 36psi, a 2psi drop with a 30 degree temp drop seems within the norm.

I'll top them off at 36psi tomorrow. This weekend I plan on going to the mountains where it will probably be below zero (f) at night. I'll report back if this worked or not. It'll also be interesting to see if altitude has any effect as there are 6000ft differences over the mt passes.

I just don't have time to check my tires every week for 1 or 2 psi. It would be good to know how the TPMS works. what is the % drop before it goes off - can this be adjusted? For folks who live in colder climates they may want a larger range to avoid the false alarms.

[tireboy]

as a tire professional. i can tell you that the tpms system is the biggest peice of garbage option that auto manufacturers have invented . on a good day i deal with people that are too lazy to manually check their tire pressures . and sooner or later you wind up destroying a very expensive tire . or wind up causing an accident because of the lack of doing simple checks. do you wait till the oil light comes on before ya check it???? ahhhh no.. we have become way too dependent on electronics to tell the motoring public what to do with our cars or trucks. what happened to checking your car's fluids and tires yourself ???? all the electronics in the world cant replace the simple checks that could potentally save your life and your family....

[live2ski]

Sorry, I'm not much of a tire guy (or a car guy). I try to by good reliable cars that require not much more than scheduled maintenance for a long life. I'd rather fix computers. do you keep your firewall/virus/OS up-to-date daily? or do you wait for the little popup to say you need an update? same difference.

the CX-9 is the first car I've had with TPMS so I'm learning the nuances of it. I would like to have it only go off if the pressure drops x% within a specific timeframe signaling a moderate leak. Sure, over time my tires will lose some air and will need to be filled. But that can happen during other maintenance like oil changes or tire rotation.

as a tire prof, you should love tpms, as we goobs will ruin our tires easier and provide you more business ;)

[jville]

Sorry, I'm not much of a tire guy (or a car guy). I try to by good reliable cars that require not much more than scheduled maintenance for a long life. I'd rather fix computers. do you keep your firewall/virus/OS up-to-date daily? or do you wait for the little popup to say you need an update? same difference.

the CX-9 is the first car I've had with TPMS so I'm learning the nuances of it. I would like to have it only go off if the pressure drops x% within a specific timeframe signaling a moderate leak. Sure, over time my tires will lose some air and will need to be filled. But that can happen during other maintenance like oil changes or tire rotation.

as a tire prof, you should love tpms, as we goobs will ruin our tires easier and provide you more business ;)

Your both right and wrong, yes it has prospect of more business, but changing a tire with monitoring systems is a PITA! and one wrong move you just bought a new sensor (about 75$) Oh and to answer ur ? my virus software and spyware updated automatically everytime i log on(trend and webroot) and they have been good so far. I uderstand your point about u;d rather work on cars, to each his own, however back in the day you couldn't own a car without know how to do a WHOLE lot more than the turn key operations today(noy even that sometimes) I guess its mainly a POV love/hate relationship.

[kosh2258]

Sorry, I'm not much of a tire guy (or a car guy). I try to by good reliable cars that require not much more than scheduled maintenance for a long life. I'd rather fix computers. do you keep your firewall/virus/OS up-to-date daily? or do you wait for the little popup to say you need an update? same difference.

the CX-9 is the first car I've had with TPMS so I'm learning the nuances of it. I would like to have it only go off if the pressure drops x% within a specific timeframe signaling a moderate leak. Sure, over time my tires will lose some air and will need to be filled. But that can happen during other maintenance like oil changes or tire rotation.

as a tire prof, you should love tpms, as we goobs will ruin our tires easier and provide you more business ;)

Checking tire pressure regularly is part of standard maintenance for any vehicle.
If you look in the owners manual Mazda recommends checking the tire pressures at each fill up, most manuals say the same thing.

Now, that said, do I check my tires at each fill up, no, I don't. But I do check them monthly, especially so in the 9 because I have the 20" tires and they aren't at all cheap to replace. So far, I haven't had to add air to the tires. But I did set pressures late last fall when the temperatures were getting down into the upper 30's and low 40's so that may have some bearing on why I haven't seen a TPMS light this winter.

Ted

[live2ski]

not that it matters, but I have the 18" wheels. in my case, the tpms went off in under 2 weeks of owning the car. I guess that's my bad for not checking the pressure. maybe off-topic, wouldn't keeping the tires slightly under pressure help with snow/ice traction by keeping the tire a bit softer?

[kosh2258]

not that it matters, but I have the 18" wheels. in my case, the tpms went off in under 2 weeks of owning the car. I guess that's my bad for not checking the pressure. maybe off-topic, wouldn't keeping the tires slightly under pressure help with snow/ice traction by keeping the tire a bit softer?

I haven't found that tire pressure makes much of a a difference in my experience (within normal limits, of course). The determining factors seem to be tread compound formulation, the tread pattern, and how much sipeing is used (sipeing is the slits in the tread - snow tires always have a lot of sipeing).

I don't mean to seem as if I'm picking on people about tire pressures and checking - not my purpose at all.
I've got prior experience with TPMS from a previous vehicle and I learned about the quirks back then. Although I do miss that system because it had a display mode that showed the sensor measured PSI of each tire and identified the low tire position. It also monitored the spare as well, which saved having to dig it out to check pressure.
The system on the Mazda, and several other brands, is pretty simplistic and not really all that useful. It meets the letter of the law but isn't worth much in terms of communicating information to the driver.

Ted

[todd92]

I have TPMS on 3 different vehicles and not having any problems.

[Craig-CX9]

Yes, I too wish that the CX-9 had the advanced TPMS sensors and monitoring. Is there an aftermarket way of reading the OEM sensors? It would be great if this could be integrated into the Scangauge!

Craig

[DSherwood]

I am amazed, I can look at a tire and see that it is low 2-3 lbs of air pressure, when I see a car on the road with low tire pressure, it pretty much tells me that they are unaware of a lot more than their air pressure when driving.

Of course tire pressure goes down with temperature, there is a great logical explanation from Jville. I can't believe how preventative maintenance is so taken for granted.

[chiurw]

I read in a car magazine that you lose approximately 1 lb of air for every 10 degF drop in temperature. Some TPMS sensors, I believe the ones installed in the Corvette, can tell you the actual pressure. However on our CX9's, these sensors are nothing more than a fancy "idiot" light. Our morning temps finally dipped into the 30's and the TPMS dummy light was on. I checked all four tires and found they were below 35 psi. Once I inflated all four to the recommended tire pressure, the dummy light was extinguished. So based on my experience, the TPMS sensors are set to trigger once the pressure drops below 35 psi, which is the recommended tire pressure. I just filled them to 38 psi to account for temp fluctuations.