275/65/18 or 285/70/17

I'm running 265/70/17 stt pros love them getting new rims only come in 17x9 or 18x9 which my tire only go's to 8.5 now I have no rubbing at all stock height I plan on putting 2.5 fox coil overs extended travel wanting as close to 3 in front as I can get over stock height can I go down 32 threads ? I know 16 equals 1 in over so 32 would be 3 ?

 

Holy crap, did you drink 10 cups of coffee just before posting this?
If you want to GUARANTEE that you will not have to trim, cut, grind on your exact vehicle and setup, keep it to 265 or below.
Otherwise get what you want and have an expectation that you will prob have to modify in some way to fit bigger tires.
Many people say on here that you do and many say you don’t. It comes down to YOUR exact truck and your exact parts. Nobody here can in no way give you any guarantees unless you stay at or extremely close to factory size and dimensions.