Tire Pressure Indicator

[Marana Rich]

Just curious. My DIC gives me a reading for tire pressure that is different from hand held gauges. My own gauge and the ones at the service station are pretty close, but always read at least two pounds more than the car. Anyone else notice any difference? Which one to trust?

My speedometer and the HUD digital readout usually show at least 1 mph difference also. Which one to trust? Going through a radar trap at +10 rather than +11 may make a difference?

[Eddie44]

I don't know about the TPS but I would trust the HUD. I have had HUD on one Pontiac and two Vettes now. I checked them all with a radar gun and all three HUD's were right on.

[ChadC]

the TPS is very, very accurate.

[Marana Rich]

I knew it registered the difference pretty well as the tires heated up, but I have been running highway speeds most of the time, and it gets up to 31-32. In the morning cold in the garage they all read 27-28. Guess I will add some air, see how it feels.

[code918]

I used the latest in speed detection (LIDAR) to test out (A) to see if the HUD display and speedometer were accurate, and (B) to see if the LIDAR would pick up the vette (due to the sharp angles and lack of any real flat frontal surfaces). The HUD is dead on, when it said 40mph, so did the LIDAR.

As for the tire pressure sensors. My tires always gain a few pounds after driving on them for a few miles. I also noticed that the tires lose a few pounds a pressure every month or so (stock F1 EMT runflats). I would think that the sensors are fairly accurate, but I would certainly trust a good analog pressure gauge over the sensors any day.

[1EVLC7]

Tire Pressure Monitor System

The Tire Pressure Monitor System (TPMS) on your vehicle, uses radio and sensor technology to check tire pressure levels. Sensors, mounted on each tire and wheel assembly, transmit tire pressure readings to a receiver located in the vehicle. The TPMS sensors transmit tire pressure readings once every 60 seconds while the vehicle is being driven and once every 60 minutes when the vehicle is stationary for more than 15 minutes. Using the Driver Information Center (DIC), tire pressure levels can be viewed by the driver. The TPMS also uses the DIC to warn the driver when air pressure, in one or more of the tires, falls below 24 psi (164 kPa) or is above 42 psi (290 kPa). For additional information and details about the DIC operation and displays see DIC Controls and Displays and DIC Warnings and Messages .

A low tire pressure warning light also appears on the instrument panel cluster when a low tire condition exists. The low tire pressure warning light will be shown each time the engine is started and stays on until the low tire condition is corrected.

Each tire, including the spare (if provided), should be checked monthly when cold and inflated to the inflation pressure recommended by the vehicle manufacturer on the vehicle placard or tire inflation pressure label. (If your vehicle has tires of a different size than the size indicated on the vehicle placard or tire inflation pressure label, you should determine the proper inflation pressure for those tires.)

As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one or more of your tires is significantly under-inflated.

Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability.

Please note that the TPMS is not a substitute for proper tire maintenance, and it is the driver's responsibility to maintain correct tire pressure, even if under-inflation has not reached the level to trigger illumination of the TPMS low tire pressure telltale.

The Tire and Loading Information Label (tire information placard) is attached to the vehicle's b-pillar. This label shows the size of your vehicle's original tires and the correct inflation pressure for your vehicle's tires when they are cold.

Your vehicle's TPMS can alert you about a low or high tire pressure condition but it does not replace normal tire maintenance. The SERVICE TIRE MONITOR message, in the DIC, is displayed when the TPMS is malfunctioning. For example, one or more TPMS sensors may be inoperable or missing. Also, the active handling system will be affected.

TPMS Sensor Identification Codes

Each TPMS sensor has a unique identification code. Any time you replace one or more of the TPMS sensors, the identification codes will need to be matched to the new tire/wheel position. The sensors are matched, to the tire/wheel positions, in the following order: driver's side front tire, passenger's side front tire, passenger's side rear tire, and driver's side rear tire using a TPMS diagnostic tool.

Federal Communications Commission (FCC) and Industry and Science Canada

The Tire Pressure Monitor System (TPMS) operates on a radio frequency and complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:

This device may not cause harmful interference.

This device must accept any interference received, including interference that may cause undesired operation.

The Tire Pressure Monitor System (TPMS) operates on a radio frequency and complies with RSS-210 of Industry and Science Canada. Operation is subject to the following two conditions:

This device may not cause interference.

This device must accept any interference received, including interference that may cause undesired operation of the device.

Changes or modifications to this system by other than an authorized service facility could void authorization to use this equipment.

[1jester]

I would recommend filling the tires with Nitrogen as your tire wil not loose pressure over time, much like air does. Mike

[Marana Rich]

Many thanks for the good input.