Re: 2012 Sahara 18" on 2011 JGC Overland
You need the 56029398AA sensors, they are used on a wide variety of chrysler vehicles (on all 2011-2012 WK2s regardless of trim or options). I got OEM ones off ebay for $65 that work great. As mentioned above, wk2jeeps.com has a detailed description of the TPMS.
Dunno what came on the wrangler, I thought I read in the suspension/wheel/tire sub-forum of someone throwing newer wrangler wheels on the WK2 without issue. . It takes about 10 minutes of driving for the new sensor to be detected.
I don't think the spare has a sensor, if it does its not monitored.