All Gladiators have a steelie spare and do not come with TPMS sensors from factory. Let's say you installed the spare after you punctured a tire, the TPMS light will flash (indicates a sensor fault) and will not read the pressure of whatever tire the spare replaced. (Will read as a dotted line or 0) The Jeep (and all FCA products) have an auto relearn system which picks up the sensors location and recorded air pressure as you drive. If you were to install a sensor in the spare, the Jeep won't pick up an extra sensor but may rather mistake it for one already on the Jeep since the signal of the newer sensor may be stronger since it's newer - or maybe it will read it fine. Shouldn't be much of a concern if you need to install your spare anyway, really just an outstanding emergency situation. The JL Wrangler and even the JK before it have sensors in the spares and can detect when and what sensor is in each spot on the Jeep (doesn't track whichever one is in spare position) so the JT may or not be programmed to do so and I'm willing to bet it doesn't given that you don't get one from factory. Personally, I'd leave the spare alone and check it the old school way every once in a while like it was done for a century - with a gauge. I even shut off my whole TPMS system. Not a fan of computers for everything I just said.