A 33x10.50 tire can in some cases fit on a stock height vehicle, provided you are using the stock rims as well. The KM2 has relatively large shoulder tread blocks and will more than likely require you to lift the 4Runner slightly, or trim areas that rub. The most common place to rub on the front end is the mud flap - which is easily removed - and on a seam that runs inside of the inner fender well. The seam can be folded over flat so that there is a minute amount more clearance, but the better bet is to adjust your torsion bars (if only seeking tire clearance and not overly concerned with droop travel and/or ride quality) or install ball joint spacers and longer shocks.
I am a firm believer in raising your vehicle as little as possible to get away with the tire size you intend to run. With that said, mount a set of 33x10.50r15s to your rims, bolt the rims to the truck and watch for rubbing. If the rubbing is minimal and only under certain (rare) circumstances, you may not need to do anything. If the rubbing occurs slightly along the seam inside the fender well under suspension compression, then look into bending the seam flat.* If the tires rub fairly regularly, then you will need to raise the front end via adjusting the torsion bars (22mm wrench, lots of solvent, and about 12 turns per inch of adjustment) or installing the aforementioned ball joint spacers.
If you have 4.56 gearing right now, you will probably be okay with 33x10.50 tires, although 4.88 gearing is optimal. If you have 4.10 or 4.30 gears you may want to consider a re-gear, or swapping 3rd members with someone looking for your ratio (and who has the 4.88s you desire).
I'm actually looking to install a set of 33x10.50r15 KM2s on my stock rims in the coming weeks. I went ahead and got 1.5" ball joint spacers, longer shocks and and a differential drop kit just to make sure I am covered. So, why would I advocate lifting as little as possible, then turn around and buy a 1.5" lift kit for my truck, even though it may not be needed after flattening the seam and/or minor trimming? Kind of makes me sound hypocritical, no? My reason is simple: install the ball joint spacers for more travel, trim as needed, flatten the seam and then let some tension out of the torsion bars so they ride nice and soft (and subsequently will allow decent flex off road). When all is said and done I hope to have 33" tires on stock rims, at or near stock ride height with 1.5" more suspension travel, a softer ride and close to stock CV axle angles. Your goal may vary.
*link to flattening the seam in the fender well:
Pinch Weld and new 33x10.5 tsl's - YotaTech Forums
