Hello fellow Jeepers ....
13 JKU Rubi
5-Speed Auto
Stock 3.73 Gears
Falken Wildpeak AT 35x12.5x17
Currently I'm looking to improve the hwy manners on my JKU as I recently moved to Boise, ID and there are all kinds of weekend trips from here that are 1-8 hour trips. Currently my Jeep feels like chore to drive at hwy speeds (70+) as it feels like it lacks power in the upper range, and tracks around quite bit. This leave me with a tired right foot and sore shoulders on trips over 2 hours.
When speaking with a friend he told me my biggest issue is the lack of regearing for the 35s and suggested that I put in 4.88. He said it will get the RPMs back up to where then need to be on the hwy and keep the engine in the power band. This makes sense to me, but I'm also worried it might make it so that its in too high of the RPM band (where the engine is screaming at you). Thoughts?
Lastly I'm going to be swapping out the Falkens for some BFG KO2s.
Any other recommendations on making the Wrangler a bit more bearable on longer road trips? I appreciate any and all feedback.
I have 93,000 km (55k miles?) on my 2012 JKUR (auto/4.10s). At least a half of that (if not more) is from long *** road trips where I'm driving 10-15 hours a day. And other than poor back support after losing a bunch of weight, I've never really had an issue with my 2012 in terms of comfort level when driving. But reading your post, a couple things jump out at me.
The tracking around quite a bit will absolutely happen with 12.5" tires. The first time I got mine on, I didn't really notice it up north where I live due to the lack of heavy semi traffic. But the first time I went down south with my 2007 way back when, I was all over the place so much that I pulled into a tire shop and was like ******!?!? Since then I've just come to accept it to an extent. It happens, and you either live with it or go to a narrower tire. I've decided to live with it, and honestly, unless I come from driving a rental (usually BMWs) or a work truck, I don't even notice it (I guess that's what 7 years in a built JK does to you).
70 MPH? Try slowing down. That's roughly 115 KPH. Yes the jeep will do that, and depending on the roads/highway and everything it's not that big a deal. But it's also possible that the jeep will behave better going closer to 60 then 70+. I know for me when towing the trailer (especially if it's windy) my jeep likes 60/100 KPH, but doesn't like 110 KPH (~66 MPH). Not sure why, but I know it pisses people off when I'm in Alberta and the limit is 110. I feel a little bad, but **** em - my comfort level is more important then them getting where they're going 10 minutes sooner, so they can pass me (I stick to the right lane whenever possible and hug the shoulder to make it easier for them to pass). And this is coming from someone who drives the BMW rentals at speeds in excess of 80-100 MPH. Your jeep will have a speed that it's comfortable at, and one that it's not. Hunt around (slower/faster) and see if it makes a difference.
Lastly, the gearing... In the strongest possible terms... I think you would find that 4.88 gears are way too much. At 60 MPH, you'd be at 2700 RPMs. But this (3.73s/auto/35s) is absolutely where your "loss of power" is coming from.
I'm running auto/4.10s/35s and at 60, am around 2200-2300 RPMs. I could go a tad deeper to help on the hills (especially when I have the trailer)... but I wouldn't want to go too deep. When I was stock, I found the gears with the stock 32" BFGs to be too low. 33s were perfect, and when I wear out these 35s, will probably go back to a 33/34 tire. Maybe I'm off base here if you plan on using this as a trail rig and whatnot... but as a DD and something that will see highway miles... there's no way I'd want to be running at 2700/2900 RPM when cruising down the highway. Think 2200-2500 (unless you live in a really hilly place). Still get decent gas mileage (for a jeep) and can still go up modest hills without gearing down.
Here's a chart to give you an idea of what the different ratio's would look like when at 60 MPH.
If you are not set on 35s, consider going with 33s as an alternative to regearing.
33s may not have the look many want, but they can handle any off road situation except big rocks.
Just to add to this. I don't wheel a ton (not nearly as much as I'd like) and I don't consider myself an expert by any means. But other than perhaps once or twice, almost every single time I got stuck when I had 33s, 35s wouldn't have made a single difference. And the few times that they might have, where all clearance issues where an extra inch might have made the difference. A good set of 33s will be enough for most situations unless you're going hard core.
