i have a 2015 jk with a 4inch teraflex and im going to be putting on 40's but i want to take off my spacers and i want to keep my wheels at 17's but im basically clueless when it comes to back spacing and i have no idea what i should shop for. currently i have 35's that stick out about 2 inches past my stock fenders (i cant remember what my spacers are, maybe 2 inch)

 

If you're going 37s or larger you really need to look at 3.5" backspacing. Most of those options are going to be beadlocks, though there are a few non-beadlock options on the market these days. I know Dirty Life wheels offer that. Typically people running 40s are going to be on beadlocks anyhow.

 

is there anything else you would recommend doing? should they fit? do you think i will have any issues with having stock fenders and steering if i avoid wheeling until i upgrade

 

Are you putting 40's on stock Jeep axle systems?

 

no I have a dana ultimate 44 on the front and a 60 rear with 5.13

 

What steering components do you have? Those 40s are going to eat ball joints on D44 for lunch. Hopefully hydro assist or big bore steering box? As far as clearances go, every jeep is different and you're just gonna have to throw em on and start examining things closely. You're not going to go less backspacing than 3.5" really. I think you're going to be asking a lot out of that axle housing. I wouldn't run 40s on anything less than a wider D60, but that is just my opinion.

You should search up and read a lot of TheDIrtmans comments about axles and 40s.