Low Tire Pressure - 2014 Mini Cooper Hardtop Long-Term Road Test

Edmunds.com

Low Tire Pressure - 2014 Mini Cooper Hardtop Long-Term Road Test

Our long-term 2014 Mini Cooper warned us to check the tire pressure, but which tire?

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random_shots

Given all four tires were down it is reasonable to suspect the change in ambient temperatures as the reason for the low tire pressure. Mornings are now 20 degrees cooler over the last few days in So Cal. Tires are suppose to be checked cold (before driving) and set to the appropriate PSI shown on the door jam sticker or owner's manual. Nitrogen is suppose to be better at reducing the deviation in PSI due to ambient temperature.

kirkhilles1

Yeah, at the time our brand new Pilot had warning lights come on! Oh no! Turns out that all 4 tires were low? Broken TPS system? Nope, just really cold weather.

chol92594

Temperature changes have caused TPMS warnings on both my 09 Civic and my father's 07 Tundra. It's a pretty common occurrence here in the Midwest. That being said, I still don't understand why all cars (especially ones as new and advanced as the Mini) don't show individual tire pressures. My neighbor's GMC Terrain does this (I think many GM cars do), but my mother's 2013 Tiguan does not, even though it has a multifunction display on the IP that would be perfect for such a purpose. That way, if all four tires were low but close to each other in pressure, you could assume that the warning is being caused by low temperatures and not an air leak.

As far as nitrogen goes, ambient air is already about 78% nitrogen, so filling up your tires with pure nitrogen will provide little benefit, if any. Plus, it's pretty much impossible to fill a tire with pure nitrogen, since air will be trapped inside the tire when it's mounted to the rim. You would have to continually fill and release the nitrogen, which would get pretty expensive.

Also, regardless of the tire type (run-flat, conventional, summer vs. all-season, etc.) you can't really tell if a tire is low by just looking at it. This has been proven extensively. If a tire DOES actually look low, it's probably well under the recommended PSI and warning threshold for the TPMS system.

fordson1

How does a car that is supposedly being maintained by a professional fleet manager get tire pressure dropping from 35 psi down to 25-28 psi?

How many times are car owners told that the TPMS is a safety net - that it's NOT a substitute for regular manual checks of tire pressures (and "regular" is taken to mean like once a month, not once a year), including on Edmunds' own site?

Donna, this happens time after time with Edmunds LT cars. Who there is supposed to be doing stuff like this?

quadricycle

Donna DeRosa said:

cafe au lait

Don't forget your accent aigu (acute accent) Donna! I'm having nightmarish visions of Americans pronouncing café as caf or cafee...

allthingshonda

I don't understand the reset procedure of driving around so the system can get a reading. In my Acura the information display indicates which tire is low and the individual pressures of all the tires. After adding air, if all tires are filled correctly, the warning light and message will turn off when the proper pressure is reached. By the time I get back in the car there is no longer a warning message and the system will indicate the current pressures. No driving around or pressing a reset button.

stever

A while back the TPMS light went off on my Grand Caravan. Topped up the tires and the light immediately went off.

This morning I woke up out of town to temps just under 20°F and the light was on, so off to the closest tire shop I go. One tire was down to ~34, rest were the "normal" 38 psi. Aired up the tire and took off but the light didn't go off. Stopped 5 miles up the road and rechecked the psi and it was holding air okay. So we continued on a 40 mile backroad through the Gila NF here in NM to the cliff dwellings. After the fourth stop (aka "driving cycle") over the next hour, the light finally went off and I was able to quit worrying about it.

darex

chol92594 said:

. That being said, I still don't understand why all cars (especially ones as new and advanced as the Mini) don't show individual tire pressures.

It does do exactly that (once calibrated).

thecardoc3

fordson1 said:

How does a car that is supposedly being maintained by a professional fleet manager get tire pressure dropping from 35 psi down to 25-28 psi?

Donna, this happens time after time with Edmunds LT cars. Who there is supposed to be doing stuff like this?

Actually this happens on "millions?" of cars all of the time and the lackadaisical approach to tire pressures and to the TPMS system by the average owner is worth a story all on its own.

thecardoc3

allthingshonda said:

I don't understand the reset procedure of driving around so the system can get a reading. In my Acura the information display indicates which tire is low and the individual pressures of all the tires.

By the time I get back in the car there is no longer a warning message and the system will indicate the current pressures. No driving around or pressing a reset button.

There are so many different systems out there , and so many different ways to use as well as service them one could almost make a career out of just this one aspect. Here is a company that sells servicing tools for shops. http://www.bartecusa.com/ Here is their training kit advertisement pdf. http://www.bartecusa.com/pdf/tpms-training-kit.pdf

Without information like this and tools like this company provides shops wouldn't be able to keep up with all of the different systems. One reason that a lot of cars have to be driven has to do with how fast the sensors go to sleep and quit broadcasting the tire pressure. When driving the sensors react top the movement of the tire and broadcast all of the time. When stopped they go to sleep in order to try and increase battery life.