2020 Sport S (3.6L/Auto) gearing question, moving from 245>285 tires

[donmontalvo]

I'm having a 2.5" lift and 285/70R17 tires installed this week.

I've been trying to read up as much as possible on all things Jeep.

ExtremeTerrain says my front axle is a Dana 30, and my rear is Dana 35:

https://www.extremeterrain.com/wrangler-jeep-axle-identification.html

Stock gearing is 3.45, whereas Rubicon (which has 285s) comes with 4.10.

Am I looking at re-gearing for the 285 tires, if needed/possible with the OEM axles?

[UPDATED with Dana info from Extreme Terrain]

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[jessedacri]

Nah you'll be more than fine on 285s. I'd venture up to 295s even, but also note you can pick up a set of five 285 KO2 Rubicon takeoff wheels+tires in near-new condition for just under $1k all in pretty often but you definitely have to be willing to wait sometimes for a set to come up in your area. Lots of Rubicon owners upgrade fast. Plenty of people on here running 35s on the stock sport/sahara gearing too, but you'll feel them.

 

[Bikemobile]

I have 285/70-17’s on my sport S with automatic and 3:45 gears. Works great. No need to change.

 

[Redneck_Jedi]

Yep, no issues with 285s on a Sport. I did the same swap a couple months back. You will want to get something like a Tazer or the JScan app to set your new tire size into the Jeep's computer so the speedometer will display your correct speed.

 

[Bikemobile]

My speedo is 1.5 mph off at 65 mph.

 

[donmontalvo]

Thanks all, I guess I’ll role with the standard gearing for now.

 

[mwilk012]

My speedo is 1.5 mph off at 65 mph.

That is unrelated to gearing, that is a programming change.

 

[jeepoch]

Don,

You'll be fine. I went with 35's on my Sport S 3.6L Auto. I'm loving this set up with a Mopar 2.5" lift. Drives great both on and off-road. The only issue is that I rarely see 8th gear anymore. Not a problem since you can always manually request 8th. However, with 285's I'll bet you won't notice any change at all.

You'll certainly have no problems. I'm not, even on bigger tires. Here are some pics to show that if 35's (315s) work, so too will 285's as well. You'll like em.

Jay

 

[donmontalvo]

I went to Moab for a couple weeks and to be honest couldn't really tell the difference.

https://donmontalvo.com/2020/08/17/moab-aug-12th-thru-16th/

However not seeing 8th gear makes me want to upgrade my gearing to 4.10 at least.

I do plan to move to 35" tires in the Spring, so changing the gearing seems to make sense.

 

[donmontalvo]

I ended up moving to Dana 44s (M210/M220) with lockers and 4.10 gearing, still using the 285/70R17s that I mentioned in the first post.

I then bought a used set of 35x12.5x17 Pro Comp (steel) wheels with Nitto Grappler MT tires.

I'm planning on a 3-4 week trip from PA to Moab>Rubicon and possibly Big Bear before coming back.

Thanks for all the info guys!

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