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Old 01-18-2012, 11:50 AM   #1
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Should I re Gear, Installed New Wider Tires

Hello all, kinda new to this and would like your help. I have a 2011 Sahara Unlimited automatic. I went from 255/70/18 to 275/65/18. I do pull a waverunner trailer and on the beach. I do feel it as a little slugglish with the wider tires on. What is the factory ratio and what should i re gear to? Thoughts? Thanks much!

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Old 01-18-2012, 11:53 AM   #2
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Post the vin # and I will look it up for you

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Old 01-18-2012, 12:49 PM   #3
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You can check your gears in your Jeep. There are 3 different factory ratios. 3.21 (usually in sports, sahara's with 6 speed), 3.73's (sports, saharas with the Tow package), and 4.10's (rubicons only for the most part).

To check your gear ratio jack up the rear end of your Jeep, put it in gear and spin the tire one rotation while having your buddy watch the drive shaft. However many rotations your DS makes in that one tire rotation is equal to your gear ratio. A piece of tape or mark on your DS helps in watching the rotations.


Rotations:Gear ratio
3 1/4 ~ = 3.21
3 3/4 ~ = 3.73
4 ~ = 4.10


More than likely you have 3.73's with an auto sahara.
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Old 01-18-2012, 01:36 PM   #4
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Quote:
Originally Posted by Sahara33 View Post
Hello all, kinda new to this and would like your help. I have a 2011 Sahara Unlimited automatic. I went from 255/70/18 to 275/65/18. I do pull a waverunner trailer and on the beach. I do feel it as a little slugglish with the wider tires on. What is the factory ratio and what should i re gear to? Thoughts? Thanks much!
You shouldn't regear. At +/– $1500 for a regear, it's not worth it for the tire change you're making.

The "sluggishness" you feel is in your imagination, IMO.

Your 255's are 32.06" in diameter; the 275's are 32.07" The difference in your revs per mile is –0.39. Your speedometer change will be +.04.

The only way it could be more negligible is if you changed your old 275's to new ones of the exact same brand.

By the way...the difference in section width of your new tire is 0.79. It's like the difference in circumference between two hairs from the same head.

Don't waste the $$ on a gear change.
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Old 01-18-2012, 01:42 PM   #5
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Quote:
Originally Posted by Sahara33 View Post
Hello all, kinda new to this and would like your help. I have a 2011 Sahara Unlimited automatic. I went from 255/70/18 to 275/65/18. I do pull a waverunner trailer and on the beach. I do feel it as a little slugglish with the wider tires on. What is the factory ratio and what should i re gear to? Thoughts? Thanks much!
I'd leave it as is and just drop air pressure down when driving on the beach.
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Old 01-19-2012, 08:28 PM   #6
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I swapped my factory gears for 4-10s, and I love it, My 5th gear is powerful enough to be useful and I can actually use my cruise control. Plus my 4HI is a ton better. I would recommend it highly.

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