Got a 2012 F250. I've read the owner's manual, and also done a search here down in the Wheels & Tires section - got about 30 pages of "results" that I tried to skim through without finding the answers I'm looking for.

If I understand the situation correctly, only the four road wheels have sensors. The spare is apparently a "temporary" tire and does not. The sensors activate what is to all intents and purposes an idiot light that tells me that one - or maybe more - of my tires is low, but not which one or how much. My questions:

1: I assume the sensors have batteries in them. How often do they need to be checked or changed? Or do I need to replace the whole sensor? How long should I expect them to last?
2: If I replace the "temporary" spare with a real rim and tire, can I have a sensor in there? Will the system then read the spare and tell me if it's low? Or will having a fifth sensor on the truck confuse the system and cause problems? Anyone here tried it/is doing it?
3: Apparently there is no AUDIBLE warning of low pressure. Anyone know of an aftermarket add on that could sound an alarm, maybe hooked up to the OBD port? Could those Scangauge doohickeys provide that function?
4: If I want to replace my stock rims with aftermarket, do most of them accept the sensor, or do I have to give up my TPMS if I go aftermarket?

BTW, regarding that "temporary" spare. Most tires are supposed to be replaced after 7 years or so, regardless of remaining tread. At some point, are we supposed to get a new spare even if we've never used the one that came from the factory?

Thanks.

 

From my understanding, the battery in the TPMS is on average last 10 years. The sensors have to be "awakened" for them to report. It tells you in the owner's manual to drive the truck a certain distance/time before doing the sensor location procedure. I would assume that one of the sensors not be "Awakened" and report to the TPMS receiver, the truck would know you are using the spare time in one of the 4 positions. I have a dually so not sure if this is correct. Have you read up about the TPMS in your owner's manual?

I have never heard nor read about the 7 year replacement rule. Most people never replace the spare unless it is bad or has been in use. I would think as long as the tires are not dry rotted or cracked from the sun and UV, the life might not be in question.

Just my humble opinion

 

Aren't the sensors programmed to each tire, so when you rotate the tires the low pressure on the left front might actually be the right rear?

 

The owner's manual provides a procedure for reprogramming each wheel to the new, correct location when you rotate them.