Using the wheel from the spare
 

I have a 2006 A6 3.2Q. Is there any downside in swapping out one of the alloy wheels with the wheel on the spare tire? I'm considering this because one of the "active" wheels is pretty scuffed up. I'll probably do it next time the car needs new wheels. I presume it has a TPMS and they are all about the same age.

Which begs the question, how long do the TPMS units last?

Thank you!