So I got a spare OE set for my GS, and I'm wondering how long the batteries last in them?
Also, and this may be a dumb question, but what would happen if I just put all 4 in the console or glovebox? Wouldn't they all "see" the same air pressure regardless? Then I could switch wheels around at will.....

 

Search the forums for a TPMS pipe bomb. That's your answer!

 

Putting all four of the sensors in the glove box would be useless. What each sensor does is transmit a signal when air pressure in a tire drops under a certain psi. The cpu that manages the TPMS also routinely sends a signal to each sensor around every 50 miles (on one trip with shutting off the car) just to make sure that the sensors are still functioning.
This is the reason why we have members that don't have the sensors installed on their rims and yet have no tmps lights on. If you keep the sensors in your glove box they will transmit the signal reading low pressure on all four tires. Again, if you drive under 50 miles on each trip you really wont have to worry about it but if you do then what zax3gs suggests is your best bet. A TPMS pipe bomb is a sealed pipe (usually PVC) that is set to about 35 psi with your sensors inside so basically it fools your sensores into thinking their in your tires.

 

The PVC deal sounds good - makes sense. Anybody know why they made the warning in these cars be 3 colors in 3 different places?? It's insane overkill-----

 

I have 3 sets of wheels that's y I have mines inside the spare tire and works great for me.