I noticed more of a difference going from 265s to 285s then I did going from 285s to 315s. I think it's partly because when I switched to 285s I also installed a suspension lift. Also, the 4runners I've had experience with always felt heavy and slow to begin with & I run BFG 315s which are just about the smallest 315s you can get.
Since you have a lift and 285s, I'm assuming you've already accepted the fact that a lift & larger tires will increase the speed of wear and tear on parts, will typically benefit from additional parts to maximize handling & your MPGs will take a hit. As long as you are willing to do some form of modification whether it's trimming, hammering, tubbing, body lift, spacers, aftermarket UCAs or a combination, you'll be able to make 315s work. It just depends on how much effort you want to put in, your driving habits, & your daily/recreational driving conditions. BUT you'll definitely need to do something to minimize rubbing with 315s especially if you're already rubbing with 285s on your current set up.
With that out of the way, the type of adventuring I do can be achieved with a stock 4runner which means, aside from maintenance, just about everything I've done to my 4runner has been to achieve a specific "look" I wanted as long as it didn't compromise its function in a manner that would negatively impact how I use my 4runner outside of my comfort zone. I'm pretty straight up & never had to kid myself that something I was doing was for function when it was really because I just liked it.
For example & only speaking for myself, the following are a few things that come to mind that was done because I liked it & had almost nothing to do with enhancing function because like I said earlier, everything that I do can be achieved in stock 4runner:
-suspension lift (to make 285s work without hammering/cutting)
-body lift (to make 315s work without hammering/cutting)
-265s to 285s then to 315s
-satoshi grill mod
-hood w/ scoop
-paint job
