i see a lot of the jeeps that have a mismatched spare on the back, or a brand new spare on the back that has never touched the pavement. i always recommend getting it in the mix as it will extend tire life by 20% if you have the room to carry it. when i had alignment problems i immediately switched my front tires to the back. after each trip out i assess the tire wear/damage from the rocks and pull the worst tire off and swap in the spare. i don't have much luck with sidewalls so the MTR-K's are what i really want to put on mine, but having a spool in the rear i wear tires quickly & it's hard to justify $1200 for tires once a year.