Gear help for a newbie
Thread Starter
JK Newbie
Joined: Aug 2009
Posts: 5
Likes: 0
From: prairieville, louisiana
Gear help for a newbie
Hello to all,
Just got an 09 2Dr. X. i know I will have to regear for 33's or 35's, just not sure what ratio. i've some some posts and have ideas, but looking for advice on my particular situation. I ofcourse dont want to lose power! This is a pleasure vehicle for the family and i still want driveability, i'm gonna say 85% highway and 15% offroad( mud), Not many rocks to crawl on in south Louisiana! We drive about 4 hrs. twice a summer on the interstate to the beach and will be taking the jeep from now on. Also I will ocassionaly pull my golf cart to the camp which is only a twenty or thirty minute drive. Not to concerned about gas mileage since this is not a primary vehicle for us. Any advice would be appreciated. I Have been reading plenty of posts and wanted to say that I joined this site versus the others because there seems to be a lot of professional and friendly people here so keep up the good work!!!
Just got an 09 2Dr. X. i know I will have to regear for 33's or 35's, just not sure what ratio. i've some some posts and have ideas, but looking for advice on my particular situation. I ofcourse dont want to lose power! This is a pleasure vehicle for the family and i still want driveability, i'm gonna say 85% highway and 15% offroad( mud), Not many rocks to crawl on in south Louisiana! We drive about 4 hrs. twice a summer on the interstate to the beach and will be taking the jeep from now on. Also I will ocassionaly pull my golf cart to the camp which is only a twenty or thirty minute drive. Not to concerned about gas mileage since this is not a primary vehicle for us. Any advice would be appreciated. I Have been reading plenty of posts and wanted to say that I joined this site versus the others because there seems to be a lot of professional and friendly people here so keep up the good work!!!
JK Jedi Master
Joined: Jan 2008
Posts: 11,463
Likes: 165
From: Austin <--> Colorado Springs
What gear ratio, transmission and tire size are you running now? You may be fine with 33's.
Which ratio you go with is a personal preference, based on transmission, tire size, load carried, where and how you drive, etc. But here is the answer from the FAQ.
https://www.jk-forum.com/forums/modified-jk-tech-2/modified-tech-faq-answers-questions-every-newbie-has-18617/
Browse through all of the sections to get a better idea of what all you may want to address when putting larger tires on. (lift, rim backspace, etc.)
Also check out the write-ups area when you get a chance. Lots of good info to get you headed in the right direction.
Which ratio you go with is a personal preference, based on transmission, tire size, load carried, where and how you drive, etc. But here is the answer from the FAQ.
Q: What gear ratio should I be running with 35" tires?
A: In order to bring your Jeep's performance back to stock, you will need to run 4.88 gears with 35" tires. However, if you are looking for a little extra power, you should consider getting 5.13's. This is especially desirable if you have an automatic transmission.
A: In order to bring your Jeep's performance back to stock, you will need to run 4.88 gears with 35" tires. However, if you are looking for a little extra power, you should consider getting 5.13's. This is especially desirable if you have an automatic transmission.
Browse through all of the sections to get a better idea of what all you may want to address when putting larger tires on. (lift, rim backspace, etc.)
Also check out the write-ups area when you get a chance. Lots of good info to get you headed in the right direction.
Last edited by nthinuf; Aug 25, 2009 at 12:13 PM.
JK Newbie
Joined: Aug 2009
Posts: 54
Likes: 0
From: Peoria, AZ
I just put 295/75/16 tires (just over 33" tall) on my 2009 2 door with 3.21 gears and six speed and it is fine. Sure it has a little less get up and go than before the bigger tires, but sixth gear is still useable on the freeway over 60 mph. And first gear on the six speed is about 4 1/2 to 1 so it comes off the line pretty well without having to rev the engine high.
I don't know how much get up and go the automatics have, but they have a 3.73 to 1 gear ratio. So they should be fine with a 33" tire. Unless the automatic really sucks up the power. And a six speed would easily be fine with a 33" tire and 3.73 gears.
If you go to a 35" or bigger tire or drive a lot in an area with a lot of hills or tow often, then you should regear. But if you stay with 33" tires you will be fine as is, especially if you have 3.73 or 4.10 gears.
Before I bought my JK, I was SURE I needed to buy one with the 3.73 gear option (after reading forums like thise one). But the only dealer in town with a good price only had 3.21 gear Jeeps left in my price range. So I test drove one with the 3.21 gear ratio with the optional 32" tires and I could hardly tell the difference in preformance than with the one I bought with 29" (225/75/16) tires. So unless you really want to have a lot of "zip" in your Jeep, you would be fine with stock gears and 33" tires.
I don't know how much get up and go the automatics have, but they have a 3.73 to 1 gear ratio. So they should be fine with a 33" tire. Unless the automatic really sucks up the power. And a six speed would easily be fine with a 33" tire and 3.73 gears.
If you go to a 35" or bigger tire or drive a lot in an area with a lot of hills or tow often, then you should regear. But if you stay with 33" tires you will be fine as is, especially if you have 3.73 or 4.10 gears.
Before I bought my JK, I was SURE I needed to buy one with the 3.73 gear option (after reading forums like thise one). But the only dealer in town with a good price only had 3.21 gear Jeeps left in my price range. So I test drove one with the 3.21 gear ratio with the optional 32" tires and I could hardly tell the difference in preformance than with the one I bought with 29" (225/75/16) tires. So unless you really want to have a lot of "zip" in your Jeep, you would be fine with stock gears and 33" tires.
JK Super Freak
Joined: Mar 2008
Posts: 1,673
Likes: 3
From: Alberta
stevens09, I'm not sure of the terrain down there...but you've already obviously done some reading on here and pre-determined that you will want to regear for your bigger tires....can I make a suggestion from experience?
Seeing as how you've even considered 35's...get yourself a 5.13 ratio, especially if you live in the hills, do it once and do it right...you've thought of 35's so get them and get yourself the 5.13's It will still handle all your daily driving needs great, and you won't be wanting when your offroading
Seeing as how you've even considered 35's...get yourself a 5.13 ratio, especially if you live in the hills, do it once and do it right...you've thought of 35's so get them and get yourself the 5.13's It will still handle all your daily driving needs great, and you won't be wanting when your offroading
Thread Starter
JK Newbie
Joined: Aug 2009
Posts: 5
Likes: 0
From: prairieville, louisiana
my jeep info
Guys,
Thanks for all the quick replys and what some of you actually have. I got 3.21's and a 6spd std. transmission. running factory tires still. Thinking of a 4" lift and really leaning to 35's. My daily driver is a gmc diesel 4wd. All my gearing experience is for pulling loads and when I hear anything lower than 4.10's I get nervous, I realize this is gearing for a diffrent reason, but I cant help it. As far as the terrain and hills down here go. do ant hills count? no hills unless manmade, very little rocks, 99% mud and water for our offroading! Would there be enough diffrence to justify 4.10 gears? Also I don't like to cut corners to save a dollar! If you can't afford it now, save until you can. Anyone have 4.10s or 4.88 gears and 35's? how is your highway and interstate performance?
Thanks for the great Info,
Stevens09
Thanks for all the quick replys and what some of you actually have. I got 3.21's and a 6spd std. transmission. running factory tires still. Thinking of a 4" lift and really leaning to 35's. My daily driver is a gmc diesel 4wd. All my gearing experience is for pulling loads and when I hear anything lower than 4.10's I get nervous, I realize this is gearing for a diffrent reason, but I cant help it. As far as the terrain and hills down here go. do ant hills count? no hills unless manmade, very little rocks, 99% mud and water for our offroading! Would there be enough diffrence to justify 4.10 gears? Also I don't like to cut corners to save a dollar! If you can't afford it now, save until you can. Anyone have 4.10s or 4.88 gears and 35's? how is your highway and interstate performance?
Thanks for the great Info,
Stevens09
Trending Topics
Sponsoring Vendor
Off Road Evolution Rep
Off Road Evolution Rep
Joined: May 2008
Posts: 494
Likes: 0
From: Palm Desert, Ca
The torque and horsepower curves on your diesel truck are very different than the JK.
Our wimpy 3.8L JK engine generates rear wheel horsepower of 56 at 1800 rpm, 64 at 2000 rpm, 88 at 2500 rpm, and 107 at 3000 rpm.
So, you want to be running at least 2500-3000 rpm at freeway speeds because your current gearing with 35s would put you at 1800 rpm. The 56 rear wheel horsepower at 1800 rpm will not be enough to hold any kind of speed. Closer to 3000 rpms is better with our engines--your diesel truck probably redlines around 3000 rpm, whereas ours redlines over 5000 rpm.
With a 2 door, 6 speed at sea level, you will want 4.88 gears, which would put you at 2756 rpm at 70 mph with 35s. This will give you enough rear horsepower to hold speed in 6th gear, and your gas mileage at 55-60 mph will be 20+ mpg.
Our wimpy 3.8L JK engine generates rear wheel horsepower of 56 at 1800 rpm, 64 at 2000 rpm, 88 at 2500 rpm, and 107 at 3000 rpm.
So, you want to be running at least 2500-3000 rpm at freeway speeds because your current gearing with 35s would put you at 1800 rpm. The 56 rear wheel horsepower at 1800 rpm will not be enough to hold any kind of speed. Closer to 3000 rpms is better with our engines--your diesel truck probably redlines around 3000 rpm, whereas ours redlines over 5000 rpm.
With a 2 door, 6 speed at sea level, you will want 4.88 gears, which would put you at 2756 rpm at 70 mph with 35s. This will give you enough rear horsepower to hold speed in 6th gear, and your gas mileage at 55-60 mph will be 20+ mpg.
JK Enthusiast
Joined: May 2009
Posts: 356
Likes: 0
From: Charlotte, NC
Thanks