Charger Forums banner

1 - 20 of 63 Posts

·
Premium Member
Joined
·
15,199 Posts
Discussion Starter · #1 ·
Also known as TPMS, or Tire Pressure Monitor System, we can expect to see a huge amount of threads about this soon. Every fall, as folks who got thier cars since last fall discover, as lower temps sweep across the country, warnings happen.

See, gasses lose volume as temperature goes down. If your tires were filled to spec (or a little low) when the outside air was say 80 degrees, then a drop down into the 50s can drop your tires down by about 3-4 psi. If your tires were hot when filled, even more so.

In short, if your tire pressure sensor goes off, and you've just had a recent temp drop like us here in MD, don't sweat it. First step is to go first thing in the AM to a place and top them off. If you don't trust the pumps gauge, buy one, they only cost a few bucks.

If the station is more than 1/2 a mile away, add an extra 1-2 psi or so to account for the tires getting warm as you drive. Then check the next AM before driving to ensure youve got it right:)
 

·
Registered
Joined
·
5,193 Posts
AT WHAT POINT-[PSI]DOES THE SENSOR TRIP THE LIGHT. i'm thinking that the sensors look for A pressure difference between the tires and not so much the pressure of each tire. why i say this is because once i let the air out of all 4 of my tires to a pressure of 25 pounds and the light didnt come on when i turned the key on BUT when i filled one tire to 38 psi and turned the key on the light came on. then i filled the other tire across from it to 38 psi and tryed it again and the light was off. so it got me thinking it looks for a pressure balance in the tires. i could be wrong tho
 

·
Registered
Joined
·
13,222 Posts
From the '06 Service Manual, p. 22-60:

The Tire Pressure Monitoring (TPM) system uses radio and sensor technology to monitor tire air pressure levels.
Sensors, mounted to each road wheel as part of the valve stem, transmit an RF signal indicating their individual
pressure to a receiver located in the Wireless Control Module (WCM), commonly referred to as the Sentry Key
Remote Entry Module (SKREEM). These transmissions occur approximately once every minute at speeds over 15
mph (24 km/h). The Tire Pressure Monitoring system remains active even if no tire pressure related message is
displayed.
The sensors lay dormant (Park Mode), then wake and start transmitting (Drive Mode) when the vehicle first reaches
speeds over 15 mph (24 km/h). Once the wheels stop rotating for a period of approximately 20 minutes, the sensors
shut down until again awaken. Although not transmitting as when in Drive Mode, while in Park Mode, the sensors
still transmit approximately once every 13 hours to let the receiver know air pressure status at that time. Sensors
will also transmit when a pressure change of one psi (seven kPa) or more is detected during that period. For more
information on sensors, (Refer to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING/SENSOR - OPERATION).
If the vehicle is equipped with the premium TPM system, transponders located in three of the four wheel wells of the
vehicle are used to provide the WCM with the location of the tire pressure sensors on the vehicle. The transponders
are located in the left front, right front and right rear wheel wells. A fourth transponder is not necessary in the
remaining wheel well due to the process-of-elimination theory. Once the system knows the location of the first three
sensors it assumes the location of the fourth tire pressure sensor is in the left rear tire. For more information, (Refer
to 22 - TIRES/WHEELS/TIRE PRESSURE MONITORING/TRANSPONDER - OPERATION).
If the system detects that the tire pressure in any road tire is going low, beyond the Low Pressure (lamp) ON threshold
(see following tables), the TPM system will continuously illuminate an indicator lamp. If equipped with the premium
TPM system, a message will be displayed in the instrument cluster. The text message will indicate which tire
is low and the display will show all current tire pressures, the low tire will be flashing with its pressure value. This
message will be displayed for the rest of the ignition cycle, or until the Low Tire pressure condition has been corrected.
A chime will sound upon initial detection. Once pressure in the suspect tire raises above the Low Pressure
(lamp) OFF Threshold, the lamp will go out and the system returns to normal within approximately two minutes time.
If a message center button is pressed, the message is replaced by the new message requested; however, if the
Low Tire condition has not been corrected, the Low Tire pressure message will again be displayed.

TPM THRESHOLD PRESSURES - PLACARD PRESSURE 30 PSI (207 KPA)
Placard Pressure (Cold) 30 PSI (207 kPa)
Low Pressure OFF Threshold 28 PSI (193 kPa)
Low Pressure ON Threshold 24 PSI (165 kPa)


TPM THRESHOLD PRESSURES - PLACARD PRESSURE 32 PSI (221 KPA)
Placard Pressure (Cold) 32 PSI (221 kPa)
Low Pressure OFF Threshold 29 PSI (200 kPa)
Low Pressure ON Threshold 25 PSI (172 kPa)


TPM THRESHOLD PRESSURES - PLACARD PRESSURE 36 PSI (248 KPA)
Placard Pressure (Cold) 36 PSI (248 kPa)
Low Pressure OFF Threshold 34 PSI (234 kPa)
Low Pressure ON Threshold 29 PSI (200 kPa
 

·
Registered
Joined
·
13,222 Posts
:bored: know it all
It might seem that way to someone who knows NOTHING! :devil: :D


And knowing where to find it is NOT the same as knowing it all! :tongue:

PS: your sig bugs me! :halloween
 

·
Registered
Joined
·
4,495 Posts
You should be more alarmed if one tire is showing a pressure different than the others. I had 32,32,32,26 the other morning and sure enough I had a nail in my tires. I dont wanna open a can of worms but isnt Nitrogen suppose to be a more constant pressure?
 

·
Registered
Joined
·
13,222 Posts

·
Registered
Joined
·
2,847 Posts
I wouldnt pay for it, but Nitrogen almost eliminates the PSI variance due to temperature
 

·
Premium Member
Joined
·
17,663 Posts
Arfur also says that if you put nitrogen in your tyres, you won't have this problem. :ninja:
 

·
Premium Member
Joined
·
17,663 Posts
You should be more alarmed if one tire is showing a pressure different than the others. I had 32,32,32,26 the other morning and sure enough I had a nail in my tires. I dont wanna open a can of worms but isnt Nitrogen suppose to be a more constant pressure?
For the past two years, a cold night/day like the past 24hrs would have set off my sensors. But so far this year, nothing.

The only difference is nitrogen.
 

·
Registered
Joined
·
5,193 Posts
You should be more alarmed if one tire is showing a pressure different than the others. I had 32,32,32,26 the other morning and sure enough I had a nail in my tires. I dont wanna open a can of worms but isnt Nitrogen suppose to be a more constant pressure?
WELL NOT IF YOU HAVE A FREAKING NAIL IN YOUR TIRE!:smile:
 

·
Registered
Joined
·
13,222 Posts

·
Registered
Joined
·
191 Posts
I bought my charger Dec 26th 2006, went through the whole summer, and now it's back down in the 40's and I have not had the alarm go off once...
 

·
Registered
Joined
·
13,222 Posts
I bought my charger Dec 26th 2006, went through the whole summer, and now it's back down in the 40's and I have not had the alarm go off once...
I check 'em once in a while anyway Randy, since the alarm won't go off until they're down to around 25-26 psi.
 

·
Registered
Joined
·
3,862 Posts
Makes me wonder if humidity makes a difference. I fill up my tires with air from my own compressor, whereas the local gas station's air supply is literally dribbling with water droplets. Consequently, I filled up my winter tires (on non R&T rims) in my warm garage last Fall to 30 psi and never once had a TPMS go off all winter even with temp drops to -30C (-20F ish).

Either that, or people are filling their tires to 28-29 psi when ultra-warm and that's what's causing a big enough drop on cool mornings. (anything warmer than 10F I consider a cool morning. :) )
 

·
Premium Member
Joined
·
15,199 Posts
Discussion Starter · #17 ·
Makes me wonder if humidity makes a difference. I fill up my tires with air from my own compressor, whereas the local gas station's air supply is literally dribbling with water droplets. Consequently, I filled up my winter tires (on non R&T rims) in my warm garage last Fall to 30 psi and never once had a TPMS go off all winter even with temp drops to -30C (-20F ish).

Either that, or people are filling their tires to 28-29 psi when ultra-warm and that's what's causing a big enough drop on cool mornings. (anything warmer than 10F I consider a cool morning. :) )
(Hands TTA a rolled up paper wrapped with a ribbon)

Congratulations, sir, you have graduated.

Yes, humididty makes a huge difference, in fact, from what more technically educated folks tell me, the only real difference. And people do have to learn to adjust for seasonal differences. Adjusting your tire pressures twice a year sholdnet be too much to ask.
 

·
Registered
Joined
·
13,222 Posts
(Hands TTA a rolled up paper wrapped with a ribbon)

Congratulations, sir, you have graduated.

Yes, humididty makes a huge difference, in fact, from what more technically educated folks tell me, the only real difference. And people do have to learn to adjust for seasonal differences. Adjusting your tire pressures twice a year sholdnet be too much to ask.
You have learned wel! :smoke:

Remember, when something goes from gas-to-liquid (or the reverse), there's about a thousand-fold change in volume! So, a drop of water expands into about a liter of gas (water vapor), and vice-versa. These state changes make a big change in pressure, inside a tire. Nothing else normally inside a tire except water undergoes this kind of change under normal conditions.
 

·
Registered
Joined
·
289 Posts
One quick question....what wrong with using nitrogen in your tires?
i just put some winter tires on the rears and i had nitrogen put in them...big difference in ride and handling..does it cuase damage? i mean ya paid for it but i dont have a way to separate nitrogen with my compressor at home and so whats the big deal..sorry if i missed something as i am new here...
thanks :}
 

·
Premium Member
Joined
·
15,199 Posts
Discussion Starter · #20 ·
Nothing wrong. just that the benefits over (properly dried) air are ridiculously overstated by the industry that makes the equipment.

The only way for nitrogen to make a difference in your ride and handling would be if your other tires were filled to a different pressure. Either your stockers were low, and these are filled with more pressure, or maybe its a difference between the tires.

When you change two variables, in this case fill gas and tires themselves, its impossible to tell which variable caused the difference you felt.
 
1 - 20 of 63 Posts
Top