My Taco has 15" on it and have had those wheels on my 4runner.
I think there is more range of tires for the 15" wheel. Plus, you can get 33's (285's) C rated while the 16" 33's are mostly E rated.
I'd be willing to gamble that you have a very select size wheel, because I've never seen anyone who has actually gotten 15" wheels to fit on their 16" wheel truck without grinding the hell out of the caliper, at the very least.
I didn't want OP to think that any 15" steelie will work, because that's simply not true. Chevy wheels, with their ridiculous offsets...? I don't know, I bought a Toyota, not a GM piece of crap.
More tires is probably right, but who wants a DD with a huge sidewall? I wouldn't even dare to think of the sidewall flex with a 15" wheel, 33" tire, and a C load rating. My load D KM2's on 17" rims are flexy as is. Most 15" off road tire selections I see are standard instead of Metric, too.
You can say goodbye to any brake upgrades, because let's face it, stock 3rd gen brakes suck a fat one. A heavy steel wheel and a large tire? You'll be paying more for rotors/resurfacing than you'll save for cheaper tires.
So yeah, there's probably a 15" wheel out there that'll work, but I think it's impractical for a 4Runner.
OP can try it, but if they don't fit, sorry dude. I'm only goin by what I've read on the forums. I remember a while back, a dude got a sweet deal on some 15" Cragar soft 8's... wouldn't you know... they didn't fit over his brakes. Then you've gotta deal with return shipping... choosing the correct wheel... blah blah blah, just choose the right wheel the first time.
