I have aggressive tires from a 2004 Ford Expdetion. That i want to put on my 2003 4runner Sr5 v6 2wd. The tires i have now are R16" and my current Lug nut configuration is 6 Lug Nuts, 6x139.7 (or known as 6x5.5). The aggressive tires i want to put on are 285/70/R17, lug nut configuration is 6 Lug Nuts, 6x135. From what i have seen online the largest you can put is 265/70/r17. Since the lug nut configuration is different i am going to buy 6x5.5 to 6x135 (Set of 4) Wheel Adapter Special 1.5 inches for around $100. Do y'all think that with the 1.5in spacers there would be good enough clearance to stop the tires from rubbing on the wheel arches? Would i need to adjust the suspension? I believe the '03 4Runners have a Torsion Bar, would i need to adjust the suspension, if so how much would i need to and how much would be adjustment is recommended without putting a strain on the cars suspension. Also is it easy to adjust?

I was thinking i may have to invest in like 1-1.5in Coil Spacers, or maybe a leveling kit, because i feel i would have good clearance at least in the back.
I dont want to cut the plastic in the wheel arches.

Let me know if putting these big tires are even possible.
I plan on keeping the old tires too so i can change them out for longer drives, so i do not put too much strain on the engine.

the 1.5in spacer will move the wheels OUT but they wont keep the tires from rubbing on the wheel arch/openings. If anything they would probably rub more since they are moved OUT of the wheel well. You can lift it to make them fit but if that's the case you may as well by some cheaper steel wheels in the proper fitment/lug pattern. Either way you will need a lift to fit 285's.

You will need 3 inches of lift in the front. Properly back spaced wheels. Remove the aft mud flaps in the front wheel well. Push the plastic wheel well liner forward in the front wheel well, new upper control arms to get caster back in spec. Possibly a body mount chop to stop the tires from rubbing. Fitting 285/70 r17 (33") tires on a 4th gen takes some effort.

I ended up with fj coils front and rear. Bilstein adjustable struts set at 1.75 on the front. Daystar 1.5" spacer on rear. And light racing adjustable upper control arms. After all of this I only put 265/70 r17 (31.6") or 255/75 r17 (32.1") tires on. I didn't want to completely kill mpg on the 75 mph highways in TX or mess with the body mount chop. I still had to push the forward wheel well plastics forward and reshape the mud flaps with a heat gun. My caster is at +3.9 degrees left and right.