The Truth about Gears and Tires

[Timmy]

I recently bought a 2016 Unlimited, auto-trans. I am having 3.5 superflex lift installed with 37" Toyo MTs. Were you saying that the two members that drove the autos preferred the 4.88 to the 4.56. Thanks. There is just so many different opinions and "experts" on regearing.

I have 37" tires and a manual trans. Technically the manual trans is providing a hair bit lower gearing than the auto so my experience may not match yours. I actually have the opposite view of Ross. I put in 4.56 gears and after having it for about a year I wish I would have put in 4.88. I often find that the gearing is just not low enough for all types of driving, city and highway. Sometimes I burn the clutch in reverse if I have to get over/up something big because it's just not enough. On the highway, I hardly ever shift into 6th gear because it just can't handle it. I only shift into 6th gear when I'm over 60 mph. I may use 6th gear at 50mph, but only if the road is totally flat or downhill.

I drove from WA to Lake Powell in Arizona by way of Montana, Idaho and then Utah. Coming in to Utah I was sucking eggs. We were about 6,500 elevation before heading in to Arizona and we had a lot of ups and downs on the Interstate. The Jeep topped out at 85mph and I couldn't go any faster, that was flat out all she had in sixth gear. Going up hill, if I even wanted to maintain 80mph, I had to draft behind a larger vehicle and drop down a gear a two. I was really wishing I had just a few more hundred RPM in sixth gear to help maintain the highways speeds as I was dropping down to 5th gear all the time. I honestly didn't see any better gas mileage in 6th gear vs. 5th.

I do know that Ross has a supercharger in his rig, and it was a manual like mine. With a supercharger, the 3.56 might be perfect, but I really think that without one you need to go 4.88. Instead of switching out my gear, I'd rather the $2k go in to a supercharger and see if I can't solve my situation with more power ;-)

Like I said, if I had to do it all over again, I would go 4.88.

Hope that helps muddy the water for you!


[UPDATE: Durp... forget to mention I had a kayak and two paddle boards on my roof to Lake Powell, so that just added to the aerodynamics of my already streamlined brick on the Interstate.]

[JeepLab]

I have 37" tires and a manual trans. Technically the manual trans is providing a hair bit lower gearing than the auto so my experience may not match yours. I actually have the opposite view of Ross. I put in 4.56 gears and after having it for about a year I wish I would have put in 4.88. I often find that the gearing is just not low enough for all types of driving, city and highway. Sometimes I burn the clutch in reverse if I have to get over/up something big because it's just not enough. On the highway, I hardly ever shift into 6th gear because it just can't handle it. I only shift into 6th gear when I'm over 60 mph. I may use 6th gear at 50mph, but only if the road is totally flat or downhill.

I drove from WA to Lake Powell in Arizona by way of Montana, Idaho and then Utah. Coming in to Utah I was sucking eggs. We were about 6,500 elevation before heading in to Arizona and we had a lot of ups and downs on the Interstate. The Jeep topped out at 85mph and I couldn't go any faster, that was flat out all she had in sixth gear. Going up hill, if I even wanted to maintain 80mph, I had to draft behind a larger vehicle and drop down a gear a two. I was really wishing I had just a few more hundred RPM in sixth gear to help maintain the highways speeds as I was dropping down to 5th gear all the time. I honestly didn't see any better gas mileage in 6th gear vs. 5th.

I do know that Ross has a supercharger in his rig, and it was a manual like mine. With a supercharger, the 3.56 might be perfect, but I really think that without one you need to go 4.88. Instead of switching out my gear, I'd rather the $2k go in to a supercharger and see if I can't solve my situation with more power ;-)

Like I said, if I had to do it all over again, I would go 4.88.

Hope that helps muddy the water for you!


[UPDATE: Durp... forget to mention I had a kayak and two paddle boards on my roof to Lake Powell, so that just added to the aerodynamics of my already streamlined brick on the Interstate.]

OMG TIMMY! Did I screw you? You followed my lead on 4.56 and regret it? That hurts me to my core.

I see no way that it could be the wrong decision for highway driving like you are talking about, but wouldnt disagree with your experience.

How heavy is your rig? lots of steel? maybe thats the difference?

[Timmy]

OMG TIMMY! Did I screw you? You followed my lead on 4.56 and regret it? That hurts me to my core.

I see no way that it could be the wrong decision for highway driving like you are talking about, but wouldn't disagree with your experience.

How heavy is your rig? lots of steel? maybe thats the difference?

Oh man, don't sweat it for a second. I researched a ton from a lot of different resources. One of the reasons I picked the 4.56 is that I felt if I erred in my decision, I would rather error too low than too high as us manual guys can always just down shift if you error low ;-) Also, I was always planning on going with a supercharger and I suspected that your own preference between the two gears was because of your supercharger. I didn't want to buy 4.88's and then toss in a supercharger and wish I had put the 4.56's in. I'd rather have the 4.56's and wish I had a supercharger and move that direction. Sadly, my damn family keeps sucking away all my fun money (haha!)

As for heavy... Compared to yours, yeah I'd be heavier. My Toyo's are heavier than your tires and I also have a full width front and rear ARB bumper. Everything else is pretty well stock so it shouldn't be much more than say 150lbs though. I can easily make that up by taking my top and doors off (which I do all summer) but even with that weight off the 4.56's are still just not enough.