Tire size, need help

What is the biggest tire size I can fit on my stock 5 lug Tacoma? I want something bigger but I haven't bought a lift yet and it's getting time to put new tires on

 

235/75r15 or 30x9.5r15

The black box mod also has to be done to prevent rubbing, but these tires should fit without a lift.

 

What exactly is the black box mod?

 

There is a "black-box" on the rear portion of the front fenders, designed in most part apparently, to keep us from using significantly larger than designed tire sizes on our 5-lug Tacoma. It involves cutting away a section of the rear 'bulge' in the plastic fender liner, and then unbolting a cab-corner cover from the frame to give additional clearance for larger than ~245/75R16.

https://www.tacomaworld.com/threads/how-to-black-box-removal.357919/

 

Also, 5-lug, gearing is an issue as you get higher in tire size. You can fit the wheels on, but you ain't gonna make 'er go if you haven't got your final drive gear ratio right.

5-lug auto, is a relatively straight-forward (if not inexpensive) regear fix.. 5-lug standard is an odd beast, and isn't quite so straight forward to rectify. 31's are about as far as you want to go, before regearing becomes a factor to consider - unless you live in the Prairies..