I'm on 33" tires now with stock 2008 gears, (3.73?) and a 6 speed manual trans. I'm never able to use 6th & the drop between gears is a long one, near 1000 RPM in the lower gears. I need to pull about 3100 RPM before shifting if any load is on it.

I was thinking 4.88s were the way to go as I trailer a boat & motorcycles alot but want to know how it'll drive/pull and ultimately the RPM at about 70 MPH. I don't mind starting in 2nd but do not want to rev its guts out at 70 either. 70 is about my top speed anyway.

Every search I make gives me a gearing chart but no real examples or the above combo. Looks like about 3300 RPM in 5th which would be near 2.9/3k in 6th right?

Thanks.

 

Are taller tires in your future?

At cruise speeds does 5th gear meet your needs?

4.88s are a lot for 33s and a manual, but if you have some plans to go taller they might be a good fit. Additionally, if 5th isn't currently cutting it for you either, and you find yourself kicking down to 4th gear, then 4.88s would be the way to go.

 

I have 35" KM2s with the stock 4.10 gears and have no issues with 6th gear.

 

I'm finding 5th to be borderline at highway cruise, dropping to 4th on long hills, especially with a pair of bikes & gear on the truck. I was playing with it today at indicated 60, which I'm guessing is closer to 67-68 and its still at only around 3k in third.

6th gear just won't pull it, I'd probably be well above actual 80 MPH to be able to cruise in 6th, and I just don't need that. Now its a 5 speed with a tall first. Dropping 1st gear use except on boat ramps would be dandy if 6th came back into the mix. I just don't want too many RPMs in 6th at 70 actual speed. 2800 RPMish at a real 70 in 6th seems where I want to be by my guesstimate.

I can't imagine a 35" with these gears, I can't say never on bigger tires but I'm pretty happy as it sits now.

 

Please verify your current gear ratio. I can't make any sense of the numbers unless you misstated the third gear reference with the speedometer reading 60mph.

Also, and something I wouldn't normally recommend for someone in need of gears, is get a Superchips Flashpaq. Not only can you get your speedometer corrected, but also get a power boost for towing. Then you can run your tests and find out what gear you are in to hold the speeds you want and need. Just not much of an idea on how much weight your pulling nor the grades your dealing with and 4.88s can be pretty steep for 33s.

Don't want to do the gear install twice and you're somewhat on the fringe of where 4.88s or 4.56s will work nest. One thing for sure, is if you even have a hint of possibly moving to 35s, just go for the 4.88s.

 

I have 35" KM2s with 6-speed/4.56 and wish I had 4.88's or 5.13's.Really...J.H.
Go LOW are leave it alone..

 

I thought all the 08 "X"s came with 3.71? Mine is a base JK. Nothing fancy. When I checked the gearing chart it didn't seem to line up either. My 60 MPH observations were as shown on speedo, my actual speed I'm guessing is near 10 MPH higher at that indicated speed. Does that make any sense?

Shucks, stuck at work and now I'm not even sure it was 3rd at 60 indicated at 3k RPMs but 5th at that speed is under 2.3k IIRC. I'm 99% sure of that 3rd gear note. Gotta wait till the ride home to confirm. Sorry, too many numbers in my head, LOL! I'll crawl under it tomorrow and check the gearing numbers on the axel too.

If I'm in between 4.56 and 4.88 I'll probably just go 4.88, I don't mind a lower cruise speed with this as the doors/top are rarely on and with the 2dr wheelbase, a few inches of lift and my usual long distance loads, slower is fine.

My loaded up weight with bikes is usually 400+ lbs of passengers, another 100 of gear and bikes on racks of 500-700 lbs. combined. My boat is around 2k lbs. total towed weight, same passenger weight.

My trips are not Rocky Mt high but alot of travel in lower NY state & NE Pa, mountainous, long inclines of around 5-6 miles at most possible. I was able, with 31" tires, to use 3rd as a decel gear on big hills to hold 35-40, now with 33" its 2nd but slightly higher RPMs. 3rd will let her fly!

Thanks for the opinions guys, definetly don't want to do it twice & my history with re-gears in cars is I prefer a little on the lower side of the scale. 4.30 in my 5 speed Mustang was great!

 

My '10 Sport came w/ 3.21's. It now has 5.13's and 32-inch tires. Since I don't run Interstates much, it's perfect. To be honest, I'm not looking forward to putting 35's on and DD'ing. Since I'm driving to CO and UT next summer, though, I think that'll be the way to go. I'm on the lookout for a Rubi transfer case.

 

You are the guy I'm looking for! (close anyway!) Any idea of your actual RPMs at true 70 MPH in 6th?

 

RPM's must be crazy high