I have a 1998 4x4 4.0L OHV
It came stock with 3.73 and 235/70/R16 = 29.0" tires
Right now it has 3.73 gears and 265/75/R16 = 31.6" tires
It seems to be making the torque converter do too much work and my highway mileage isn't any better since my driving is not a "steady 65" in which case these gears would do good.
So I am thinking of regearing but can't decide between 4.11 and 4.56 gears.
Looking at this chart and approximating the rpm values for the 31.6" tires I end up with these values.
multiplied by 0.75 to account for OD at 65mph
3.73 - 29.0" - 2107 rpm
3.73 - 31.5" - 1940 rpm
4.11 - 31.5" - 2137 rpm
4.56 - 31.5" - 2372 rpm
Max BHP = 160@4200rpm
Max TQ = 225@2750rpm
Now I see that 4.11 gears would set my truck back to around stock but with the higher rotational mass and rolling resistance of the tires I was thinking of going to the next step up. I am just worried that it would be too over-geared however it is closer to and still below the max TQ rpm. Most of the driving I do isn't on the highway so I would like a little better pep and acceleration through town. Is there anyone else running this setup, do these figures seem right?