Gear ratio for 37s

JeepKeeper said:
I'm so up in the air on regearing now:sigh: I have a '12 JKUS with 3.73s and 35s. Can't decide to go 4.88 or 5.13. It'll be a while before I swap out the D30 for a PR44, if it ever happens. So I'm not really sure about going with 5.13s in the D30. My Jeep is 90% highway driven and will probably be that way the whole time I own it. I do plan on moving up to 37s eventually. Would I be good running 4.88s since my Jeep is mostly on the highway?
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Well, the teeth on the the 5.13s are fairly small for the dana 30. I recommend you get the 4.88s which (according to the gear chart above) is in the performance range for 35s and I think you'll be happy with them. Especially on the highway. Once you go to 37s you'll loose a some highway diveability but I thin you'll still be happy.

2014 JKUR
 
I'm doing everything I can to talk myself into 4.88s instead of 5.13s like most people would recommend. I know of the pinion being a lot smaller with the 5.13s in the D30. I tell myself that I plan to wheel more when the Jeep is paid off, but I just don't see myself doing anything crazy enough to need 5.13s or anything stronger than a D30, especially where I live. With the calculator on 4lo.com, there's only about a 130-140 RPM difference between 4.88 and 5.13 on 35s or 37s. Think I'll be regearing to 4.88s this winter. Thanks for the reassurance fellas! :thumb:
 
JeepKeeper said:
I'm doing everything I can to talk myself into 4.88s instead of 5.13s like most people would recommend. I know of the pinion being a lot smaller with the 5.13s in the D30. I tell myself that I plan to wheel more when the Jeep is paid off, but I just don't see myself doing anything crazy enough to need 5.13s or anything stronger than a D30, especially where I live. With the calculator on 4lo.com, there's only about a 130-140 RPM difference between 4.88 and 5.13 on 35s or 37s. Think I'll be regearing to 4.88s this winter. Thanks for the reassurance fellas! :thumb:
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I would be careful saying i dont see myself going harder. Once your rig gets bigger your going to look for the hardest think you can find.
 
I run 5:38s and honestly couldn't be more pleased. whether i am doing 90 on the freeway or 1 in low gear, they really perform well with 37s.
 
For 35" tires I would say D30: 4.88 — D44: 5.13 or 5.38

Of course you can run 5.13 in a D30 but I don't know if the performance is that worth it for the potential risk if you like to wheel hard.



TrailRidden said:
I run 5:38s and honestly couldn't be more pleased. whether i am doing 90 on the freeway or 1 in low gear, they really perform well with 37s.
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Are you running any upgrades to the axle? Gussets etc? And for how long? Thanks!
 
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my '13 JKUR 6 speed on 35s goes under the knife today. Yukon 5.13s, arctec axle armor kit, synergy ball joints, and ARB diff covers. i was very anxious over 5.13s instead of 4.88s but after reading this thread i think i'll be ok. the shop said 5.13s since they know me and they know i'll be on 37s on the next set of tires. might as well be ready.
 
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