Should I regear

Jerry Bransford said:
For your particular 4-speed automatic transmission, you want nothing less than 4.88 gearing for 33" tires. Personally I would go with 5.13. No, not even 5.13 will cause excessive highway rpms. 5.13 would cause the rpms to be right in the middle of the optimal power band at 65-70 mph. 4.88 would just barely be in the optimal power band.

The engine will be lugging with higher ratios like 4.56 or 4.10 with your transmission and 33" tires.
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But what about when pulling a trailer? My '06 LJ with the auto tranny says to turn off the OD when pulling a trailer. That would put me at 1/1 with the tall gear. I hope to pull my popup camper when all is said and done.
 
DickD1911 said:
But what about when pulling a trailer? My '06 LJ with the auto tranny says to turn off the OD when pulling a trailer. That would put me at 1/1 with the tall gear. I hope to pull my popup camper when all is said and done.
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You take it out of od when towing due to the ultra tall overdrive gear. That won't be an issue with a gear swap.
 
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I've got a 2000 4.0 with the 5spd manual on 33s. Bought it that way
I regeared from 3.73 to 4.88 about two weeks ago and had no idea how much power i was missing having the stock gears on there. Works WORLDS better on the rocks too.
Id say go for it.
 
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Definitely re-gear. You'll be thanking us after you do. It will transform the way your vehicle drives, especially adding larger tires.
 
Mark Young said:
Old Gear Ratio × New Tire Size ÷ Old Tire Size = New Gear Ratio
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It isn't as simple as that. You also need to overcome the new tire weight, width, etc. Example:

3.73 x 33 ÷ 30 = 4.10, nobody with any actual experience and knowledge in gearing would recommend going to 4.10 and running 33's with the exception of the 3 spd auto. That is the problem with those gearing charts. That use a mathematical formula instead of experience and actual use.
 
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Rob5589 said:
It isn't as simple as that. You also need to overcome the new tire weight, width, etc. Example:

3.73 x 33 ÷ 30 = 4.10, nobody with any actual experience and knowledge in gearing would recommend going to 4.10 and running 33's with the exception of the 3 spd auto. That is the problem with those gearing charts. That use a mathematical formula instead of experience and actual use.
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Exactly. For example... running the same rpms with 35's that worked fine for 30's would quickly illustrate the problem with that and the resulting loss of performance.
 
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If the official rule was to follow the mathematical calculation, people whose Jeeps came stock with 3.07 and 29-30" tires would be regearing to 3.73 for 35's. Yikes. That's quite far from optimal for 35's no matter what the engine or transmission combo is.
 
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