factory rear diff gear ratio

2001 tacoma reg cab 5 speed 4x4 2.7l what would be the best biggest tires im going to are 33 12.5,s

 

Here's some data:

The axle code for your rig can be found on the manufacture's sticker located on the driver's side door jamb as follows:
First digit:

A = 7.5" ring gear
B = 8" ring gear
Next two digits:

01 = 3:42
02 = 3:58
03 = 4:10
04 = 4:56
05 = 3:15
06 = 3:91
07 = 4.30
Last digit:

A = 2 Pinion, Open
B = 4 Pinion, Open
C = 2 Pinion OEM Limited Slip
some '98-00 models have shown a BO code of "???" on the door plate; so far this turns out to be a 3.91 gear ratio, at least for the 5sp. RZN171L-CRPDKAB with factory 31s/265s should be 4.56 with the AT.

 

Probably 4.30s

 

Sounds reasonable blackdawg. Won't he have to do some trimming with 12.50's?

 

yes, trimming and hammering for 12.5s