JKU Rubi, auto, 3.8....4.5 lift 37s. 95% dd 5% mud and hills..aint got no rocks her. thanks

 

Just picked mine up after getting 5.13s installed so no more experience than from the shop to my house and it drives so much better. I have 35's on an auto 2010 rubicon. Wish I would have done it sooner.

 

I live at 7200' and have a 2011 JKUR with 37x13.50x17 Toyo MT's and 5.13 gears. It is great in town but still has a hard time pulling the mountain highway passes of Colorado. I am loaded up with bumpers and winch and I am getting 14.8 MPG with Amsoil in all boxes and engine.

 

37 Toyos, 4.5 lift rubi manual with 5.38s. Drives great, but a touch low for 37s. I pull a M101a2 and the low range is great for that. If it wasn't for the towing I'd be at 5.13

 

I had a 2011 JKU with 37s and 5.38s. Ok for off road use, perhaps too low with the Rubicon T-case. Ok for around town. Still geared too tall for highway use, and downshifted for any grade (6000 to 10000 feet altitude), or on flat ground when driving into a headwind. 5.86 gears would be better for the mountains.

 

2010 JKU auto with 5.13s and 35s. Lots of hills around here, and rocks. For street driving seems about right. Getting 16 MPH around town

 

5.38's will definitely give you more power but, the pinion will be really really tiny and be a weak point. trust me, i speak with experience here. if you play hard in the 5% you take your jeep out or give it a lot of throttle to work the mud and hills, i might recommend you stick with 5.13 as it will be a lot stronger. but, that's just me.