I have a Sport S without max tow, Rubicon take off wheels that I want to have 315/70/17 BFG ko2 put on. Getting mixed answers on if spacers are needed. I had to add spacers to my Jk when I added the 315s to stock wheels but I’m sure about the JT.
Rubi take offs are 7.5 wide. Many tire shops won't accept the liability of mounting a 315 on a 7.5. And many won't install spacers. I'm sure you'll find one willing to do both no problem... but there is a reason some shops won't do it in the first place.
I don't blame them, I'm generally not a fan of spacers. Buy the wheels with the proper offset you need, don't force wheels and hubs to accept stresses they were not designed for. Your diffs will probably scream at you as well. Don't show up to a dealer with massive tires on spacers with any drivetrain, suspension, or braking issues. You'll get your JT red flagged and basically invalidate any part of your warranty other than infotainment.
If you're dead set on doing this anyway... yea you'll probably need spacers. Mounting a too wide tire on a rim not wide enough to safely accept it is going to push more sidewall inwards, which you'll probably need space to safely clear without rub.