Love those rims Spish, especially in silver. I've been doing a boatload of research lately (too much) and came across your thread. I thought I'd share specs of wheels that I came across. Like you, I was only looking at OEM wheels. This is by no means a complete list.
First, the specs of the original 3rd gen alloy wheels (5-star or split 3-spoke): 16x7, 15mm offset, 6x5.5" bolt pattern, 106mm bore (this is important because our wheels are hub-centric), 4-5/8" backspace, 3-3/8" frontspace. (Front spacing can be used to estimate how far the rim might stick out or "tuck" in from your fenders.)
Other OEM wheels that will fit (all are 106mm bore and 6x5.5" bolt pattern):
- 1st gen Tundra/Sequoia, 5th gen 4runner SR5 and TE: 17x7.5, 15mm offset, 4-7/8" backspace, 3-5/8" frontspace (no spacers needed, rims will stick out 1/4" more than stock).
- 5th gen 4runner Limited: 20x7, 15mm offset, 4-5/8 backspace, 3-3/8" frontspace (FS same as stock).
- FJ Cruiser: 16 or 17x7.5, 15mm offset, 4-7/8 backspace, 3-5/8" frontspace (no spacers needed, rims will stick out 1/4" more than stock).
- 4th gen 4runner: 17x7.5 or 18x7.5, 30mm offset, 5.5" backspace, 3" frontspace (spacers may be required or else rims will be "tucked" in by 3/8".)
Any corrections or additions welcome!
Some useful links:
Wheel Terminology
3rd Gen stock OEM wheel backspacing (offset) w/ pics - YotaTech Forums
http://www.toyota-4runner.org/3rd-gen-t4rs/33980-stock-oem-4runner-rim-offset-backspacing.html
http://www.toyota-4runner.org/3rd-gen-t4rs/53387-put-new-wheels-today.html
Toyota Rim Backspacing - Toyota Tundra Forums : Tundra Solutions Forum
http://www.toyota-4runner.org/3rd-gen-t4rs/63492-new-look-2.html