Good call. I hadn't thought of that. They're at 45 psi... THANK YOU!
My 2 cents, I don't think you should have noticeable wandering issues. I don't. Is yours a 2.0L? Mine is a 3.6. It does not wander and I don't think it should. The only time I notice it is in cross winds (and worse above 65 mph), then yes there is a small amount, but not general around town driving. I would make sure suspension is torqued down correctly. I run 37 psi as listed on the placard. Yes, lowering air pressure will reduce MPGs slightly. You might want to go test drive a few Jeeps on the lot and see if it's your Jeep or if it's just you not being used to it.
Having just gone down this rabbit hole myself, the first thing I would recommend any new JL owner is to familiarize yourself with the ESS/battery system. The AUX batteries tend to not last long and can drain the starting battery as well as cause a host of other electrical gremlins. It's also easy to blow a fuse if you are someone else doesn't know that with the main battery terminals disconnected the leads are still hot from the AUX and if the pos touches anything grounded in the engine compartment it can blow the fuse on the fuse array. Many carry a spare fuse array ID: 68368854AA. I would also recommend to bypass the AUX battery.
