Just wondering if anyone could help me out here. I've got a used jeep and was wondering how I could find out the gear ratio?
It has 31's on it and it isnt hard to break them loose.
at 60mph on the highway I'm running about 2400rpms
It's an auto if that helps?

 

90% bet there 3.55s

 

I know thats the stock ratio but I thought with larger tires my RPMs would drop lower because of that. Oh yeah, and my overdrive is working

 

at 70 im running 2200 with 33s and stock gearing. 31s dont make that big of a difference.

 

do you know of anyway I could find out for sure?

 

up in the search type in gear ratio chart. it will give you what you need

 

thanks man
the formula works and you were right.
60mph x 3.55ratio x 336/31inch tires = 2308rpms
thanks again

 

could possibly be 3.73. because i think mine runs about 2200-2300 at 60mph. i have 3.55.

 

i bet that is from the differences in actual tire size. ive seen 31s that measure 28.5 and 31s that measure 32 1/4. tires are dumb when it comes to common sizes

 

yeah, you're kinda right.

 

with an auto you have "slippage" even in lock up