the problem is most 18" wheels if not all of them that will fit the 4runner are 18x9" and a stock tire size of 265 wide will not fit, the rim is too wide. I think you need at least a 275 wide tire, a 275/65/18 would only be .4 inches taller, you could run that without any lift with a 0mm offset wheel.
So 18" wheels are going to be too wide for tires that will increase my height w/o rubbing is what you're saying? Forgive my ignorance.
For Example:
Mine are 18x8 with 35MM off set, so that leaves me at close to 5 backspacing, which is .5 difference from stock. Basically, they fit.
Not gonna lie - that sounds pretty crazy to me that your wheels even fit with those specs without rubbing (I'm assuming you don't rub). 8" width and 35mm offset comes to BS of 5.88". Most of the talk I have seen on here is that you should try to stick to around 4.5" BS (as you even mentioned yourself).
Are you running wheel spacers with those?