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Pro's/Con's between 5:13 vs 5:38 and 37's"?

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Old 12-25-2016, 11:00 PM
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Default Pro's/Con's between 5:13 vs 5:38 and 37's"?

Going to do a gear swap as Im moving from 35's" to 37's"....I'm currently running 4"10's in my D44's with a "standard" transmission.
Needing a little direction in regards to which way I should I and why?
Forgive me if this has been addressed already somewhere here. I tried to do a search but wasn't really coming up with anything that broke it down.
Thanks in advance!


**** Disregard all last. I located a graft here that broke down tire size, gear ratio, RPM and transmission type.****
Found that both gearing is acceptable for 37's" just a slight RPM deviation.

Last edited by rlm8541; 12-25-2016 at 11:36 PM.
Old 12-26-2016, 03:50 AM
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Keep in mind that gear chart is using real world tire measurments, and not just what is stamped on the side of the tire. My 37" Nitto Trail Grapplers run about 35.75" inflated to 28psi.
Old 12-26-2016, 07:43 AM
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5.13 for a standard is good enough. 5.38 is too steep for highway with the 6spd.

I run 5.38 with 3.8 auto and 37s and it's perfect.
Old 12-26-2016, 03:59 PM
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Which engine? 3.8 or 3.6?
Old 12-27-2016, 09:37 AM
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Thanks for all the inside....greatly appreciated.

In regards to the engine in my 08' JK I have the 3.8 with the 6spd OD standard trans. Has only 26,000 orig. miles.
Old 12-27-2016, 11:03 AM
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I run 5.13s on my 3.6L auto with 37s (about 35.75" at 28psi). That is pretty close to you running 5.38 on the standard tranny with comparable tire. I love it for off road......it's a tad aggressive for the interstate. I'm around 3k RMP running at 75mph, and take a little bit of a hit on the fuel economy. It's not my daily driver though, and it beats having no guts when you need to pass someone.



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