For those out there who can not resist a new toy it looks like a great item. But for those who truly want the correct tire pressure a good analog (not one of those cheap pencil stlyle) tire guages would be a better deal and much cheaper. All you have to do is check the pressure every time you fill-up. The other problem is that this gizmo warns you of over pressure. If you ride on the highway for about a half an hour your pressure will be over the recommended because of heat build up. I don't think thats particularly good information for the general population. This is just my humble opinion.
My assumption on how this would work is that the tire sensors would send msgs with a "tire id" and current pressure AND temperature to the monitor. From the monitor, you'd be able to program both the expected "cold" tire pressure, and the maximum "hot" temperature. So it shouldn't go off after driving for half an hour.
I'd want to know more about how it works before purchasing one for myself though...
Is there some installation specific id? (e.g., if two cars with this system are parked within the 20ft rf range, could there be any confusion)
They say the sensors are powered by batteries that last about four years. Can the batteries be replaced after that, or do you have to buy new sensors?
Is the monitor battery powered? Is there a cord going to a 12v outlet in the car? Is it hardwired into the car?
For cars like the Prius where you might want the front tires a bit higher pressure than the rear tires, can that be handled by the monitor?
It looks a lot like the system that was in my 1999 Corvette. The sensors simply radio the information to a central computer. Except in the Corvette, the system was already built-in, so there was no "stand up" display.
I think the GM system is unable to tell you what the pressure is...instead, it measures the PSI "change" from the initial calibration, then displays the "derived" value for you.
That's not necessarily bad, but it's important to know, because whenever you change or rotate the tires, you'll probably have to recalibrate the sensors to...
A) Tell the computer which of the four corners each sensor is at
B) Tell the computer what the initial pressure is in each tire
...so if I'm right, you'll still need an accurate tire pressure guage.
My Vette used to have two tires that always had a slow leak; even after I bought all new tires, those wheels still exhibited a slow leak.
Being able to check them from inside the car, and/or having the obnoxious "low pressure" alarm go off for one or more tires was actually a nice "early warning" telling me I need to check and fill them up...BEFORE getting that flat tire from driving on underinflated tires.
Why was the system so nice? Get this; Goodyear was the only place in town that sold Runflats for the C-5 Corvette (even the dealers didn't have them!). They were $1,600 for a set of four...and they were each unique, uni-directional tires (not rotatable)...isn't that INSANITY? But the pressure system and alarm helped me SAVE one or more of those tires a couple of times.