Tire pressure telltale

[Southern Boy]

If you're getting low tire pressure indication around 28 psi and the normal tire pressure should be 33 psi. It appears that the TPS is set at around 15% or 16% of normal tire pressure.

 

[Southern Boy]

I’ve been reading about the TPM systems on this car since I never had a car with TPM s before.
The information I read stated that when the tires are rotated the ECU has to be reprogramed to the new locations of the tires. Is that the experience of those of you who have had these systems? Do you have to take the car back to the dealer or is this done where you rotate the tires or does the ECU detect the new location itself?

Just some added information on TPM sensors.
This web site
http://www.sherco-auto.com/tpms.htm has a complete listing of TPMs (among a ton of other things)

This is a hyperlink to the most comprehensive cross reference for TPMs I’ve seen.
http://www.sherco-auto.com/TPMS Application Chart.pdf

 

[dg_moore]

I’ve been reading about the TPM systems on this car since I never had a car with TPM s before.
The information I read stated that when the tires are rotated the ECU has to be reprogramed to the new locations of the tires. Is that the experience of those of you who have had these systems? Do you have to take the car back to the dealer or is this done where you rotate the tires or does the ECU detect the new location itself?

Just some added information on TPM sensors.
This web site
http://www.sherco-auto.com/tpms.htm has a complete listing of TPMs (among a ton of other things)

This is a hyperlink to the most comprehensive cross reference for TPMs I’ve seen.
http://www.sherco-auto.com/TPMS Application Chart.pdf

I'm not so sure about the reprogramming requirement. I have snow tires with tpms on spare rims. When I swap in the fall and spring the TPMS syncs automatically with no need to reprogram. I know they are sync'ed because when I get a low pressure warning the correct tire is always indicated.

 

[mcginnpm]

As a previous poster mentioned, our atmosphere is already comprised of about 78% nitrogen. Purifying it to 100% has never been proven to be cost-effective, let alone a proven difference in vehicle performance.

Here are the only up sides I know of about nitrogen in your tires:

1) The nitrogen molecule is larger than the oxygen molecule, so "molecular level leakage" should be reduced and tires should stay inflated longer. The logic here is that properly inflated tires provide better mileage and performance, thus a "slower leaking" gas will maintain proper tire pressure longer. The obvious counter to this arguement is to check and adjust your tire pressure regularly.

2) Nitrogen is a "dry" gas (i.e., when it is produced, it has no water vapor in it), thus reducing heat build-up in the tire, which is why they put nitrogen in race car, heavy commecial truck, and aircraft tires. The key word here is dry, not nitrogen. The air pump at your local gas station fills your tire with ambient air. If its one of those hot, muggy summer days when you fill up your tires, you are going to put A LOT of water vapor into your tire. For anyone who's studied water in its various forms, you know that water can retain and release A LOT of heat. It also plays havoc with the total gas pressure inside the tire, especially if it cools and condenses into a liquid form. If you were to fill your tires in the high deserts of Arizona, you'd probaby be getting just as much benefit as filling with pure, dry nitrogen.

3) Nitrogen is an inert gas, whereas oxygen is reactive (its an oxidizer). Thus, there should be less deterioration of the rubber compounds on the inside of the tire with pure nitrogen. But air already is 78% nitrogen, so I don't see this as a significant benefit. The outside of the tire takes a much worse beating and I worry more about some kind of deterioration working from the outside in, vice the inside out. Take a look at the inside of a tire with tens of thousands of miles on it when they remove it from the wheel and tell me how much deterioration you see.

If these benefits are worth the cost of nitrogen, then by all means feel free to spend your money on it. My money is on keeping my tires properly inflated and filling them on cool, dry days.

 

[rwlewis]

From HMA Service Web site info...

The Genesis Sedan uses a Low Frequency initiator near each wheel to force the TPMS sensors to transmit one at a time at each ignition cycle. This auto locates the sensors and checks their health.

Thus there is NO need to do any programming when rotating the tires.

 

[Jimmmmbo!]

Here are the only up sides I know of about nitrogen in your tires:

Well stated.

The only addendum should be that the gas station compressed air is not "Oxygen." It is general air that we all breath, which isn't signifcantly different than the (78%) nitrogen mixed with it.

Nit-pick: Nitrogen is not an "inert" gas; but it is certainly inert for our practical needs.

 

[Slider]

I had my light come on as well when the temp dropped here in Houston to the 30s...light went back out after it warmed up. I took a pressure check and all were normal.

 

[Mark_888]

I had my light come on as well when the temp dropped here in Houston to the 30s...light went back out after it warmed up. I took a pressure check and all were normal.

Boyles Law.

 

[Admckillip]

Boyles Law.

About to post the same thing. Pressure in a closed system is proportional to temperature. The colder it is, the lower the pressure will be in the tires. It's not a problem with the sensor. It's physics.

 

[gray devil]

My tire pressure telltale went off at 29 PSI when the weather got colder. I checked all the tires and they were at 29.5 except for the left rear it was the one at 29 and the one which was showing to be the low tire on the telltale.

As for nitrogen, the dealer had the tires filled with nitrogen when I purchased the car. I have since just added air. My question is, if Hyundai recommends 33 PSI in my tires filled with air, I believe there should be a different and perhaps higher tire pressure required if the car is filled with nitrogen.

Hyundai designed the car to have the tires inflated at 33 PSI cold and they have taken into account that the air pressure will increase as the tire heats up. If you install nitrogen and the nitrogen pressure does not increase as much as air would, then I would figure the tire pressure would be too low at operating temperature.

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[rwlewis]

It may be significant to note that the tire pressure module also triggers based on rate of change in pressure. Thus a car parked in a warm area (garage?)may experience a rapid decrease in pressure when taken outside in the winter.

I do not think there is a separate message or indicator for the rate of change type alarm as opposed to the absolute pressure alarm.

 

[Mark_888]

My tire pressure telltale went off at 29 PSI when the weather got colder. I checked all the tires and they were at 29.5 except for the left rear it was the one at 29 and the one which was showing to be the low tire on the telltale.

As for nitrogen, the dealer had the tires filled with nitrogen when I purchased the car. I have since just added air. My question is, if Hyundai recommends 33 PSI in my tires filled with air, I believe there should be a different and perhaps higher tire pressure required if the car is filled with nitrogen.

Hyundai designed the car to have the tires inflated at 33 PSI cold and they have taken into account that the air pressure will increase as the tire heats up. If you install nitrogen and the nitrogen pressure does not increase as much as air would, then I would figure the tire pressure would be too low at operating temperature.

You do not need to use different tire pressure for nitrogen rather than air. It is true that if there is a lot of humidity in the air in your tires, the tire pressure may change more rapidly (up or down) than nitrogen, but that is not a big deal since:

1. If you use a decent air compressor (without obvious signs of water in the hose) it will not be much different. Admittedly, I have seen some air compressors that spew water, but just avoid those.

2. If you are driving at higher speeds and moist air expands faster than nitrogen, then that is not all that bad since it is usually better to use more air pressure when driving at higher speeds.

Race car drivers need much more precise tire pressure since they taking curves at 200+ MPH, and a tire that does not perform as expected due to variations in tire pressure could cause a race car to lose control.

The 33 PSI value is for cold tire pressure (about 70 degrees F ambient temps when tires have not been used for several hours).

 

[nadel]

my r-spec sedan has p235/45r, continental compact as oem tires. using dial type "accu gage" ($40 us)and setting front tires at 34psi with rear tires at 36psi i have noticed a sharpness and MUCH better handling in corners!.granted the ride is a bit more firm than with lower psi settings but not uncomfortable. try it see what u think