(Me) being one of the most Hard-Headed and stubborn people I know.
I can't leave this topic (TPMS) alone..I just can't.
After reading several automotive reference sources I've discovered that there are two different approaches to TPMS. The Direct and Indirect versions. The GK Fit made the leap to the Indirect version of this system which is something totally new (to me).


The Indirect Tire Pressure Monitoring System (I-TPMS) used a different approach. The I-TPMS puts more "responsibility" into the hands of the car owner that the Direct-TPMS (or TPMS). With the TPMS there are pressure sensors in each wheel. With I-TPMS the tire pressure is read indirectly through an external sensor as part of the ABS sensor.


From what I've read there are several major TPMS sensor manufactures that are totally AGAINST I-TPMS !
Why...because of $$$$


Here is what one (major) TPMS sensor manufacture (Schrader) has to say about I-TPMS:
~~~~~~~~~~~~~~~
Additionally, in order for indirect TPMS to work effectively, all four tires must be inflated to the correct recommended pressure and be under optimum conditions. This seems like a defeating proposition for consumers, because the very reason they see the value in TPMS is to help them maintain the tire pressure to begin with. Similarly, indirect technology requires the consumer to install specific tires when replacing the originals in order to operate properly with the system. Last, if all four tires are similarly low in tire pressure from neglect (a common problem) or other reasons, an indirect system will not trigger a warning alarm. When all four tires are low, the tires wear quicker on the edges and the car is unsafe to drive, unstable and more likely to roll over; has less traction on wet roads; takes longer to stop; and uses more fuel. With so many variables about indirect TPMS that leave your brand vulnerable to dissatisfaction and warranty issues, direct TPMS just makes sense–for consumers and for you.
~~~~~~~~~~~~~~~
Keep in mind, in the last word sentence the word "you". They are not talking about the car owner. They are talking directly to other TPMS sensor manufacturers.
Here is another "industry leader telling the American consumer what they "really want"...I have to call BS on this whole TPMS game.


Here is a link to the whole topic for your pursing pleasure.
Direct vs. Indirect | The Schrader Difference | TPMS Made Right | Sponsored by Schrader

 

A company saying the competing model is dangerous and totally sub par??? Ya dont say...

 

like Edison v Westinghouse?

 

Hey, if I manufacture buggy whips I'm going to say that automobiles are dangerous! Direct TPMS is obsolete and no manufacturer is going to go back to a system that is more expensive and troublesome if they don't have to do so.

Schrader is spreading some definite incorrect information. The whole point of the TPMS button is to calibrate the system so tires do not have to be closely matched. Schrader's own system isn't accurate enough to maintain tire pressures so that argument falls flat too. The research cited in the article was paid for by schrader and we all know that the answers to survey questions are often swayed by the way the questions are phrased. They didn't acutally survey TPMS users, they simply asked questions like "Would you prefer a completely automatic TPMS system or would you prefer one you have to manually reset?" Any person who is not knowledgeable about the systems will naturally pick the fully automatic system. Now, if they had phrased the question "Would you prefer a system you can reset yourself or a system that has to be reset at extra cost at a dealer?" the answer would be very different. You can guess which question was likely on Schrader's survey!


Indirect TPMS is clearly superior because it uses existing hardware. Kettering's law states "Parts left out don't require maintenance and do not fail!

Another advantage to indirect TPMS is that you can set the optimum pressure to whatever you want. I tend to run more pressure than the manufacturer suggests because it improves handling and reduces shoulder wear. I can set the pressure, hit the TPMS button, and the system is now set to my specification, not some lower number selected by a sensor manufacturer.

The third advantage is that owners can have winter tires on separate wheels without having to buy and program new sensors.

 

well what happens to those few who have staggered setups?

 

If the stagger is within the range of the TPMS system it should handle it. Otherwise it will throw an error.

TPMS does not compare wheel revolutions directly as they are never the same. It memorizes the relationship between wheel speeds and displays a warning when one of the tires changes its speed in relation to the others. This should be able to handle a stagger.

 

Well said George. The more moving parts you have, the more maintenance you have, the more weight you have (and in this case its rotational weight), the more cost you have, the more headaches you have, etc. etc.