The 4.62 should work well with the 235 tires, the 5.125 will work well with a 31 or 32. You may lose a bit at highway speeds with the 31's because the torque converter lock up doesn't like big tires and most likely will not lock, adding about 400 rpm to your normal cruising speed.
I have the same year and style as yours, 95 Geo Tracker 3 speed auto with 5.125 gears. I run 32 x 11.50 BFG AT KO tires and sometimes wish I would have went with the 4.62's for better highway rpm.