Best tire diameter for 4.56 gears on a DD? - Jeep Wrangler Forum

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Old 09-29-2011, 09:13 PM   #1
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Question Best tire diameter for 4.56 gears on a DD?

2006, stock non-Rubicon 42RLE tranny, stock non-Rubicon transfer case, 4.56 gears, 33 x 12.5 x 15 BF Goodrich T/A KO tires, 2" budget lift.

With the 33s it bogs down often. Going up a hill in a 40mph zone consists of 2 options: constant shifting between bogging/slowing down and revving until exceeding the speed limit, or turning off O/D to stay in 3rd gear. Sometimes it will hunt between 3rd and 4th on flat ground at 45mph.

Since it's far easier to get a smaller tire than it is to change the gears, I'll just step down in tire size if that makes a better daily driver setup.

Or, maybe the problem is the 42RLE and I can't do anything about it?

This Wrangler will "sometimes" go off road. Which is to say, it doesn't really need 33s.
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Old 09-29-2011, 09:22 PM   #2
Knows a couple things...

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The problem is with the 42RLE's ultra-steep overdrive ratio which is why it doesn't perform well with 33" tires. The 42RLE's overdrive ratio lowers the engine rpms so low that the engine bogs far more readily than it does with other transmissions. 4.56 with that particular transmission is better suited for 31" tires. For 33" tires, 4.88 is optimal with the 42RLE transmission and 4.0L engine.

This is why I always recommend going to a lower axle ratio than is normal (like 4.88 instead of 4.56) for most other transmissions when there is a 42RLE transmission installed.

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Old 09-29-2011, 09:22 PM   #3
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That's too bad, the PO or whoever regeared it should've gone to atleast 4.88 with that transmission. I would say 32" or 31"?
|2004 Jeep TJ "Green Machine"|4.0L 5 speed Dana44|33x12.50x15 Goodyear Duratracs|2.5" OME HD coils + 1.25" body lift|OME NitroSport shocks|4.56 gears|Skid Row Engine Skid|BCC Sliders|Currie AntiRock|
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Old 09-30-2011, 05:38 AM   #4
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Thanks for the replies!

31s is what I was suspecting, and will be just fine for the level of 4-wheelin' I expect to do in the next few years.

It wasn't me who had the gears put in, I would have done 4.88.
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