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They call me "MR FLAT TIRE"
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Discussion Starter · #1 ·
as some of you know, I'm getting ready to SAS (14b & D60) my rig. Planning on running 38 or 39.5 TSLs. with my 4.56's and 35 BFGs and E4OD...I wasn't as impressed with the torque when dragging a trailer (fairly often). If I were to jump up to 5.13...is that only gonna put me back to like stock gearing with the new tire size? Would I need to run up to 5.38ish to have it be better while towing.
This is still gonna be a wheeler (especailly in the snow), but more of a tow rig and EB recovery vehicle. *might even get into some mud running and truck pull stuff*

what are you running in your rigs with 38"+ tires?

Am I missing something else in the driveline? :banghead
 

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I think 5.13 would be good enough for you with 38's. That'll give you just a little more "oomph" than stock, but it should still work well for your engine and tranny combo.

The rule of thumb for gears is 1/10 of ratio for every 1" in tire size change. So, if you had 30" tires stock with 3.55's (a common combo on Broncos), then really, to get back to "stock" gearing you'd need 4.27's. However, I think a better gear for towing in a stock configuration is 4.10. So, 4.90 would be the closest to stock. But, at that tire size, you also have to compensate for the additional rolling weight of the bigger meats. So the 5.13 should get you over the hump and give you great seat-of-the-pants launches.

5.38 would feel great, but might be just a tad too low for 38's, if it's gonna be primarily a street rig. However, they would give you room to grow if you know that some time in the future you may go even bigger.
 

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They call me "MR FLAT TIRE"
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4,802 Posts
Discussion Starter · #4 ·
sewiv said:
Try looking at the HUGE sticky on gears.
:goodfinge I did that when I did the first swap and wasn't satisfied with the results....so this time I said FAWK IT and wanted some REAL opinions instead of a straight out of the chart guestimation. :beer

Really trying to make this the last time I fawk with the gearing.


Pete-
I wasn't planning on mainly a street rig...my street use of this will be daily though-with a trailer about 1/2 the time. Mind you my trailers weigh nearly as much as most guys rigs. Maybe that is part of why I wasn't satisfied with 4.56 and 35....?
Thanks for the input...it is helpful.
 

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5.13 are probably all the lowere your gonna find with the 14 bolt. I have heard about 5.38's for the 14 bolt but they might be hard to find.
 
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