Charger Forums banner
1 - 17 of 17 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter · #1 ·
All,

How sensitive is that tire pressure monitoring system? Got in to the car yesterday and the light was on. Took the tire pressure of all tires and around 23-25psi so I guess it is working, just was worried that I had a flat. I might still have a slow leak and that would suck. Just didn't know how sensitive that system was.

T
 

·
Registered
Joined
·
251 Posts
Isn't the recommended pressure 30psi (as per the manual)? If so, then 25psi would definately set off the system.

I think that 1 or 2 psi would set it off...I had the same happen last month when the tempurature dropped 15 degrees. Once the tempurature went up, the light went off, so pretty sensitive I would think.
 

·
Premium Member
Joined
·
15,199 Posts
Yep, I dont recall the exact trigger values, but I think its about 4-5psi lower than whatever stock is for your car. SRTs are 32, and I think triggers about 28 or so. If yours is 30psi, then 25 should do it.

Today, temps were about 38 at 5am. I was at 30 or so. By lunchtime, temps will be in the 60s. And my car should be right on the money at that temp. 32psi.
 

·
Registered
Joined
·
2,847 Posts
25 PSI is the threashold for the light to come on....per LX service manual.
Run the PSi that is stated on the inside of your door
 

·
Registered
Joined
·
381 Posts
All,

How sensitive is that tire pressure monitoring system? Got in to the car yesterday and the light was on. Took the tire pressure of all tires and around 23-25psi so I guess it is working, just was worried that I had a flat. I might still have a slow leak and that would suck. Just didn't know how sensitive that system was.

T
The same exact thing happen to me yesterday. Weird...
 

·
Registered
Joined
·
928 Posts
yep mine came on exactly at 25, pulled into a shop next to work and they said wow, they are all at 25lbs, did your light just come on or what?
 

·
Registered
Joined
·
2,522 Posts
Mine alarm at 28psi. 07 SRT 32psi recomended. when hot they go up to 34-35
when cold they drop to 30. I had a slow leak a couple weeks ago and they did their job well.
 

·
Registered
Joined
·
926 Posts
Yeah yesterday both mine and my wifes car went crazy with 3 low tires. It was the first cold day of the season. Alittle air in them and now everything is good.
 

·
Registered
Joined
·
1,017 Posts
mine came on where my analog gauge read 29 at all 4 corners..... I think I'm just going to put a piece of electrical tape over the light since it is one of the most useless things if it'll come on 30 seconds into a commute when my tires are nowhere near flat.

FYI, I just put on my winter tires the other day and gassed them all to 32psi when I installed them.
 

·
Premium Member
Joined
·
15,199 Posts
Holey? Lets see if I understand. A few days back, (temp then, please), you filled your winter tires to 32psi (using the same gauge?). What did you use to fill, home compressor? Inflator? Any moisture control in whatever you used?

What I suggest is getting another gauge, borrowing one, whichever, and checking your gauge. Also, what were temps when you got the low readings. I know here in MD, we are seeing 65 or so in daytime, and lows can be low 40s.

A 20 degree swing can itself account for 2-3psi.
 

·
Registered
Joined
·
74 Posts
My system lit up Monday afternoon. I checked my tires with a cheap tire gauge and saw about a 4 pound difference between the highest and the lowest. I was not sure how sensitive it was, and I did not think that the transducers were that sensitive or accurate. I was ready to take it in to the dealer until I did some research on here yesterday. I then built my own tire gauge from a pressure gauge we had in the shop calibrated it against our pressure standard. When I got home I set all of the tires at 32 psig and sure enough the light went out. It surprised me how sensitive these pressure transducer are in our tires.
 

·
Registered
Joined
·
1,017 Posts
Holey? Lets see if I understand. A few days back, (temp then, please), you filled your winter tires to 32psi (using the same gauge?). What did you use to fill, home compressor? Inflator? Any moisture control in whatever you used?

What I suggest is getting another gauge, borrowing one, whichever, and checking your gauge. Also, what were temps when you got the low readings. I know here in MD, we are seeing 65 or so in daytime, and lows can be low 40s.

A 20 degree swing can itself account for 2-3psi.


I swapped in my winter steelies earlier this month and it was probably 60 degrees out when I did it. After storing my tires for 8 months they had dropped to about 28 and my light had already come on that day when I put on the winter tires. I drove to the gas station and put in air to get all the tires up to 32. The frickin' gas station charges $0.75 to run their pump... so it better have some super-duper moisture control.

My gauge is the one on the left (with the release valve)



I guess I just don't see why the TPMS needs to be so frickin' sensitive. That's annoying.
 

·
Premium Member
Joined
·
15,199 Posts
Me thinks its that sensitive to give the driver maximum warning that stuff is about to get ugly. When I had my flat, I was cooking along at about 70-75.

System alerted at 28, as it should, I started slowing, looking for a place to get off the road. If it didnt trigger til say 10psi, I would have had to stop on the side of the road, not knowing how much time I had to get stopped.

With low profile, stiff sidewall tires, the driver might not know they have lost pressure til too late. This lewts them know its getting bad faster.

As far as falses, its all about knowing the system, and working with it. Winter coming? First cold snap, be ready to adjust your pressures for that season. My tires right now are set for about 30-31 psi at about 40 degrees. SInce my trigger value is 28, it would need to drop to 20 degrees overnight to trigger an alert. If we start seeing temps that cold, I'll adjust to suit.

Come spring, I'll wait til overnight low temps start being in the 60 degree range, then set my pressures for 30-31 at 60. Goal is that at lunchtime, heat of the day, my tires, which I have not driven on since morning, are at recommended cold pressure.
 

·
Registered
Joined
·
2,069 Posts
Best thing you can do is fill the tires with nitrogen.

Benefits over compressed air:

1) Nitrogen is less susceptible to expansion/condensing from outside temps which cause those fluctuating pressures. Also, from daily driving.

2) Won't bleed down over time because nitrogen molecules are bigger and have a harder time escaping through the bead or imperfections in the rubber.

A standard practice in the aerospace industry.
 

·
Premium Member
Joined
·
15,199 Posts
Damn, this just keps coming up. :)

1. Given equal rates of moisture in the gases, the expansion rates are similar. Dry air = Dry nitrogen

2. Unless you have a leak, this again is nothing measurable between the two gasses, remember, air is %78 nitrogen. I filled my tires last fall, with air from my compressor at home, and 10 months later, when I went to get new tires, the pressure was eactly the same, at the same temp.

The reasons its standard practice in the aerospace industry are not really applicable to passenger cars. They use it becuase they store tires for long periods between filling (they actually get a "storage fill at realtively low pressure, with final fill being done when they get mounted on the aircraft) and usage, and when they do use them, the use is incredibly harsher than any car short of a Bonneville salt flats car. And lastly, fire is much more of a concern for them.

Still dying to see a real side by side with nitrogen and air, wish there was someone local to me doing it. Id fill one side with air, one with nitrogen, and watch the pressures real time.
 
1 - 17 of 17 Posts
Top