What to gear? In the middle of having mods installed on 2011 Rubicon 2dr Manual. Teraflex 3inch four arm lift, bilsteins, rockhard bumpers, warn power plant, 35 inch BFG-KM2-MT. Summers northern rockies, Winters Arizona. Newbie learning fast.
75 percent mostly very rough off roads, small amount of rock crawling. 20 percent highway and 5 percent city. These tires appear when mounted will be 34inch. Should 34 be used in chart in the facts section ? From real world experience, what would be good gearing ( 4.88 or 5.13 or other ) . Would like reasonable rpms at 60-65mph. Mpg not a big concern. Understand that compromises must be made.

 

Check out the chart in FAQ...

https://www.jk-forum.com/forums/modified-jk-tech-2/lets-talk-speedo-correction-17051/

https://www.jk-forum.com/forums/show...ery-Newbie-Has

 

My honest opinion? I love the way my Rubi manual on 35s drives with the stock gears and a superchips. RPMs are very reasonable, even up to 80mph. With 4low and the automatic throttle compensation, i havent ever felt the "need" for lower gearing. Will probably change when i jump to 37s or 38s though!

-Adam

 

Thanks very much for sharing your experience. My big concern of staying with 4:10 is that summer driving will be at elevations of 6000-9500' most of the time. Still trying to fiqure what my real rpm numbers will be at 60-65mph with various gear ratios.

 

Can't help you with 60-65mph, but the numbers for 70mph in the charts are pretty accurate. And yes, a 34" height for those tires should be close enough. If you aren't going to be spending lots of freeway time at 75+, 5.13's would probably be the better choice for you given the altitudes and the speeds you are asking about.

 

Thank you for verifing that 34inch in charts would be good for that tire and your thoughts 5:13 being maybe better for high altitude. Would it be reasonable to assume from the chart that since 5:13s at 70 are 2982rpm that 5:13s at 60-65 might be 2700-2800 and 4:88s at same 60-65 might be 2500-2600? I am wondering if that is indeed the case that since the 4:88s are still shown to be in the blue range on the chart, would they may be a better choice? I know I am cutting some fine hairs here, but being so new to this , am trying my best to minimize costly mistakes.

 

I run 35" KM2s and still have the stock gears in my 2 dr manual Rubicon. I have a very similar setup as you regarding weight (bumpers, winch, etc.) The only time the gears are ever an issue for me on the highway is climbing Loveland Pass or Vail Pass here in Colorado. Outside of that I can drive up and down I-25 at 75 mph running about 2500 rpms. Gas mileage is still good, 16.7 around town and about 18 on the highway. I used a ProCal to recalibrate and verified speed with a GPS. I have accepted the fact that my Jeep is just not a fast vehicle and simply enjoy the ride. The only way I would consider regearing is if I went to 37' tires. Off road and on rocks, I have never had a need for lower gearing. Good luck with your decision.

 

Either will work, but you need to decide what you want to build for:

Lots of higher speed freeway - 4.88
All of the conditions you actually mentioned - 5.13

 

I'm planning on running 4.10s with my 35s. well see how it goes. If i dont like it ill re gear.

 

I still have 4.10's in my 2 door rubi and it's fine for now. If you have a lot steep hills you'll be climbing on the daily you'll want to regear. Other than that it's not to bad for now, although i do plan on reagearing after i buy all my other goodies.