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So I ordered winter wheels for my 2012 se hatch with the sport package and decided not to spend the extra money on the TPMS sensors. So I put the winter wheels on yesterday fully expecting to see the tire pressure warning light. And... nothing. So I figured okay maybe I just need to drive it. So today I drove it about 20 miles round trip to/from work and still no tire light. What gives? As far as my car knows it doesn't even have wheels on it right now. Why no warning?
 

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I have been starting to wonder about that too.

My fuel economy dropped when the temperature dropped for a week, so I was expecting my tire pressure to have gone down with the temp.

So I started wondering if so why the Tire Pressure Monitor hadn't gone off, and what is the threshold to set off the sensor.
 

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The tire pressure sensor is supposed to be set about 25% below the recommended pressure.

The sensors are 'pinged' every so often and not just on 100% of the time.
(how often I do not remember)
This is to save battery life in the wheel portion.
PS how can you know when to replace the battery in the wheel sensor. and what battery does it use?
 

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I had put winter tires without the TPMS on my car last week. It took a few days before the tire low pressure warning lights came on.
 

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TPMS on this car is not good. I had to drive over 20 miles for it to detect there was a spare tire in use (same as you would without TPMS sensor since the spare doesn't have a sensor).

Useless if you have a low tire and it takes that long to tell you. What's the point? Just a hassle when you switch rims/tires dealing with sensors, for a sub par system.

And no it's not typical, other Ford vehicle detect changes immediately.
 

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It's designed to detect loss of pressure, when you have a puncture.
It will detect immediately if you have a puncture.
The Sensor tells the car, not the other way around.
The car checks with the sensors periodically not constantly.
 

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It will detect immediately if you have a puncture.
How do you know this? Have you tested your vehicle?

I have tested how mine works. I dropped the tire pressure under 25% TPMS threshold. Just like not having a TPMS sensor present, it didn't alert me of the low tire pressure until 25 miles of constant speed down the road.
 

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It's designed to detect loss of pressure, when you have a puncture.
It will detect immediately if you have a puncture.
The Sensor tells the car, not the other way around.
The car checks with the sensors periodically not constantly.
Same way all of my previous cars worked.

My BMW notified me immediately that there was a puncture, where as a different time when I put on the spare, it took the system quite some time to throw a fault.

Want to test it out? Start your car and get a knife.
 

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i had snow tires installed with the sensors. After driving approximately 60 miles, the low tire pressure warning came on. After a minute or two, it went off and about 300 miles later, it hasn't come back on. So now I'm also wondering about the TPMS.
 

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I hit a pothole at low speed--I didn't think twice about it. A block away, I got the three-chime warning and the message center displayed, "Low Tire Pressure." Got out and there was a definite hiss as I watched the tire deflate.
 

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I hit a pothole at low speed--I didn't think twice about it. A block away, I got the three-chime warning and the message center displayed, "Low Tire Pressure." Got out and there was a definite hiss as I watched the tire deflate.
Well someone has proved it, It has done what it's supposed to do.
By the way the sensors only work if the wheel is actually rotating.
If it's standing still it does not trip the chime.
The sensors look for a rapid decrease in pressure.
 

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Picked mine up last Friday, Saturday morning the low pressure light was on. I checked all the tires and sure enough rear driver side tire was at 23 psi. I added air to about 40 psi and again the next day it came on again, same tire was low so i am taking it to dealer this morning to have it fixed.

Looks like it's working the way it should. btw.... I have the 18" low profile tires and even with it being about 20psi lower than the others i could not tell with a visual inspection.
 
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