I did some searching about the gear ratios and now looking for some clarification as I am new to this. I'm looking into buying a 2012-2013 unlimited. I know I read if you are getting bigger wheels and tires you'd probably want 3.73 instead of the stock 3.21 but I didn't know if that was ona stock or lifted where you might go up to 35" tires. I plan on leaving my jeep stock height and just adding probably 32-33" tires whatever kits stock and probably some metal front and rear bumpers. Need y'all's opinion on which gear ratio I'd want and how much difference they'll be.
Larger diameter tires effectively raise your gearing. Plus, heavier off road tires have more weight (more mass) for the engine to get spinning when acting through the drive train and gears. The lower gear ratios, meaning higher numbers, are needed for the engine to effectively transmit power to larger diameter tires and heavier tires. The issue of lift is secondary. The main issue is the non-stock tire's diameter and overall weight. I would say go to the 3.73 if you want to go to tires larger than stock - either larger diameter or heavier in overall weight.
just go with 3.73. no reason at all to get 3.21 unless you are extremely concerned about gas mileage and if that is the case, you shouldnt be buying a jeep. 3.73 does just fine in the mileage catagory anyway
my 12 Sport S had 3.21's with the 6-speed and I now have a Willys with 3.73's and a 6-speed. the 3.73 gears give you so much extra power, driving it just feels better. in my 12, I felt like I couldn't even use 6th gear unless I was going 65 mph. I remember driving my Willys for the first time and literally saying, "whoa," with how much quicker it felt.
Ok my follow up to this since I'm looking at a used one probably from a dealership that took it in for someone. How can you tell what ratio it has? I emailed one dealer and he just replied with basically a brochure that shows you want jeeps come with and what's optional.
Call or go into a dealer with the VIN number and ask them to look up the window sticker, it will be on there. Or parts or service can look it up through their system as well
Just drive it and watch the tach. If it has factory tires get it up to 60mph. DO NOT USE OVERDRIVE. If it has 3.73's you will be almost exactly 2500 rpm. If it has 3.21's you will be well under 2500 rpm. 4.10's, well over 2500 rpm.
You can use the VIN to be sure, but it sometimes takes a few days to get a reply. By looking at the tach you will be 99% sure just taking a test drive.
You're better off finding one with 3.73's. There are a lot of JK's with 3.73's, especially ones with auto transmissions. If you find one that has 3.73's and also the optional limited slip differential that would be a good choice.
If it's got a hitch the odds of it being a 3.73 have increased. There is one dealer around me that sells 3.21 almost exclusively, while the dealer I bought from ordered a whole lot of 3.73s, and they got my business
This is correct for the most part. However, I know at least in 2012, maybe 13 also the factory was putting in 3.73's for auto trans. JK's as "standard". It was most likely a running change because the Chrysler web sites still indicated that 3.21's were the "standard" gear ratio for non Rubicons. If you find a JK that you like get the vin and research it so you definately know which ratio is in it. Like I previously indicated I think you'll find that most 12 autos have 3.73's.
Depending on the year, you could find some Rubicons with 3.73 gears but most got 4.10 and at this point, they're back to 4.10 only on the Rubicons as far as I can tell.
Early JK's with the 3.8 V6 had 3.73's in a lot more models than the 2012 and newer with the 3.6. But 3.73 gears have been an option in all non-Rubicon models. There's nothing that restricts it to "limited" editions. They're just more or less common depending on the year.
Newb question here. For JK's that swap gears around....say 3.73's or 4.10's with 35" tires. Will the speedo's be close enough to not worry about it? Or would one need to have some finer tuning done to get the speedo 100% via a hand held tuner?
Aside from the speedo, running tires it's not set for will also effect your miles. If you think you might ever sell your jeep, you'd want the miles to be accurate, not overrun just because you have the wrong settings in the computer...
At least that's my thinking...
You can get a Procal for about $125. It'll fix the tire size plus a lot of other things. It's a really nice gadget to have.
Stupid question ... But when all the charts and members talk about tire size and gear ratios.... Are they talking about actual tire size .... Or the 35 tire size from manufactures. What I mean is most 35 tires are not actually 35 "....so when thinking of re gearing do you go by actual tire size?
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Ask a question
Ask a question
Jeep Wrangler Forum
9M posts
468K members
Since 2005
A forum community dedicated to Jeep Wrangler owners and enthusiasts. Come join the discussion about reviews, performance, trail riding, gear, suspension, tires, classifieds, troubleshooting, maintenance, for all JL, JT, JK, TJ, YJ, and CJ models!