Driving a JK from 2010, mainly on the highway. Installed 32" Tires, but at 60mph (Max Allowed Speed in Holland) only 1700 rpm. I think this is to low, and with headwind i need to switch the OD off, because jeep isn't happy.

What gears should I buy?? Stock is 3.73. Would 4.58 do the trick, or 4.11??

Thanx in advance

 

Welcome to JKF.. With the 3.8L .. Do you have plans to go with any larger (taller) tire in the future.. Is this a DD only or do you do much Off Road and if so what is the terrain? This chart is a good reference point:

 

You don't mention it being an auto or manual, and that matters. I'd presume based on the rpms you say you're cruising at that it's an auto. Given your top speeds in the country, if it is an auto I'd go 4.88. I've always found the charts above to be pretty accurate. Note the @70 mph......so if you shoot for something that is 2500+ at that speed it would likely settle you about ~150rpm or so below that at your top speed where the engine is going to be more responsive. Just my opinion. You will never find it financially worthwhile to change 1 gear set as there is little difference. You need to move 2 at least, and even moving 3 doesn't make it feel like you just added a supercharger.

 

@Jay2013jk : I use the jeep as a daily driver, and no trail or off road use (not possible/allowed here) and with fuel prices rocketing over here, fuel consumption is an issue.
@ resharp001: I am driving an automatic, and mainly highway. The fourwheeldrive is used sometimes in winter. If I understand you correct, you suggest a 4.88 gearset, which would bring rpm's at 60 mph from 1700 to 2200. what would this do to fuel consumption??

 

I'm not suggesting .. the chart indicates that a 4.56 in an Automatic at 70 MPH would have the engine RPM at 2300.. Which is probably at the top of the green economy scale. Personally I run 4.11s with 35s (actually 34" when measured) in our 6spd. In the Chart 4.10s @ 70 would put you at the 2000 rpm range..

 

4.88s @60mph would probably be more like 2400 +/- rpm I'd guestimate. Everything is a trade off, so with better performance (higher revving) you're going to sacrifice some fuel economy, though you could also argue that the transmission is having an easier time of things with the lower gearing so that offsets things a bit too in your favor. All-in-all I think most the time a regear isn't going to have this huge dramatic change in fuel economy all other things being equal. The real issue is that most the time people are regearing cuz they've lost so much performance due to large tires and extra weight, and THOSE are the things that really hit the furl economy. I'd sacrifice a bit of fuel economy for a more enjoyable ride any day.