Cons of regearing - Page 2 -
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post #16 of 20 Old 09-05-2012, 11:09 PM Thread Starter
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2012 JK Wrangler 
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With that being said 5.13s would work fine for me even though my driving is mostly hwy? I often drive mine between 75-80 mph and I feel safe doing it. The jeep seems plenty stable even with my 35s and lift. Overall I just don't want to "overgear" myself in an attempt to gain a few Mpgs. I'm getting 15-16 now but would love to see some 18s or so.

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post #17 of 20 Old 09-06-2012, 05:33 AM
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In a 2012 wrangler with automatic and the 3.6L Pentastar motor, 5:13's are going to be too low of a gear (numerically higher) and you'll be running 3000+ RPMs on the highway with 35" tires.

Another source from the FAQ: Which shows you engine rpm, speed and in which gear. Overdrive numbers (highway) are on the bottom row.

You can download an excel chart and play with the numbers. I still say 4:1 or 4:56 to keep your motor in a good efficient range for both power and best MPG.

Keep in mind, you're driving a brick on wheels. I would say 16MPG is fairly decent given you already have 35's. Best way to increase that is to take your 75-80MPH and drop it to 65-70MPH and enjoy the ride

09 JK Jeep Green Sahara Unlimited / Teraflex 2.5" Spring-Shocks / 35's x 16" Level 8 Trackers/ Aussie Locker Front / 5:13's
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post #18 of 20 Old 09-06-2012, 01:41 PM
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I have just had 4:88's installed on my 3.6 with 37's. I could not find any definitive information on ratios for the 3.6's only speculation so I took a chance.

After driving it for a few hundred miles I would run 4:88's with 35's and jump to 5:13's for 37's. Although one would have to take our altitude into consideration, 6000ft above sea level sucks power.

At 75Mph I am sitting at just over 3000rpm (Yes, that is our legal speed limit on freeways ) which is under stock if I remember correctly.

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post #19 of 20 Old 09-06-2012, 04:04 PM
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The way my 12 Sport Auto feels 5.13 would be overkill on 35s with it - pure genocide with the stick! And I love gears!

J Wm Bishop EA, ASADE
The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a
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post #20 of 20 Old 09-06-2012, 07:34 PM
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You really need to listen to your fellow '12 drivers. Its a whole different ballgame with the rest of us. I don't regret my 5.13s, but my 2 door is ungodly heavy and I have the 3.8. I would think your 80+ more horsepower would lead you to 4.88s or so. (Though in my case I still bounce between 14 and 16mpg. But I am geared for power not top end)

5.13s for you seem suited for bigger, heavier tires than you plan on running. But once again, refer to my first sentence.

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