I have to disagree on this according to my experience. I have 3.21s (unfortunately) and I'm just at 2000-2100 RPM on stock wheels which measure to be closer to a 31" than 32"

The chart says that I should be at 2022 for this combination. If someone is that far off, maybe they do have different gear ratios or they need to measure their tires one more time. Hell I'd love it if my dealer put in the 3.73s on accident

 

The chart data is mathematically correct. Again it uses actual measured size of the tires diameter. Tire diameter is measured from the ground to the shoulder of the tire. It does not take into account any converter or clutch slip which would be minimal with a locked up converter or engaged clutch at cruise speeds. If you see differences beyond ±5% recheck your tire diameter, reaffirm your gear ratio and should that fail you likely have a slipping clutch or torque converter.

 

I'm running 38" toyos (37.7") on my 2012 jku with 3.73, it's my DD planing to go to 4.88s. I'm leaning more towards better economy! And I don't want my automatic to be searching for the right gear to go into, really annoying!!!! All so like the idea of the R/P being a little beefier over 5.13 or 5.38s. I'm not a hard core rock crawler type guy, but do enjoy it now and then ;-) mostly trail riding, hunting & fishing. Just want to here some feed back! RUBICONS ROCK ;-)



Scored a 1035 on RTI Ramp

 

My build sheet says I have 3.21 gears but I run 2000-2100 rpms at 70 mph. The chart suggest I have 3.73 gears. I have a procal to set my speedometer but maybe its off still. I run 1800 rpms at 65 mph. Oh yeah 35" tires.

 

35s and 3.21 gear ratio ? ...... Good luck with that !

 

You must have a heavy foot then, because I received well over 16.5 mpg with mine on a 3.5" lift 1"BL and 3.73's with 35's on my 2012 JKU Sport.