I'm planning on getting a set of BFG KM2 285/70/R17's..
Most people running them are complaining about the consumption and reduced power.
As my JK is my daily driver and will mainly be used for overlanding, I have no need to go bigger than those.
However, I want ideal performance and consumption.
I'd prefer not to fiddle with the computer with something like superchips.
I'd rather regear.

Will regearing to something like 4.56 with an auto Rubicon get figures similar to stock?

Fuel here is about $5 per gallon, so I can't afford heavy consumption that comes with bigger tires and not doing anything to get figures similar to stock.

 

honestly, i might try running your 33's or 285's without regearing first. make sure to recalibrate your speedo so that the shift points are correct and, if you can afford it, run something like a superchips. i think that you will find that with that alone, your performance will not be so bad and, being that most of what you'll be driving is flat ground, your mpg will not suffer much if at all. this is a much cheaper route to go and, if in the end you still feel like you need to regear, yes, 4.56 will be about what you want.

 

I'm curious to see what loss of fuel economy you will get with only moving up to 33's.

I went to 34.75 Nitto Trails and a 4" lift and only lost 1mpg highway....

Good luck with your choice....

 

I have a 2011 sport with the stock gearing. I went to 33" km2 for 16 inch rims. I get around 15 city and 22 highway

 

I regeared to 5.13's for my 33'' Duratracs and love them, granted I was used to driving with 3.73's and OD off all the time, which put me at 3000 RPM's on the highway. Now I turn about 2750 RPM's at 75 MPH. I get around 15-18 MPG city/highway, which is up from 14-16 MPG with 3.73's. The biggest hit to MPG is my lift and wind resistance. I drove on the interstate this last weekend with a 21 MPH headwind blowing against me. The computer readout showed 14-15 MPG on the highway at 65 MPH, a 3 MPG drop from wind alone.

I may have been able to get marginally better MPG from 4.88's, but the power I get with 5.13's is just rediculous. I'v yet to downshift on any grade on the highway, even when driving through the foothills of Georgia.

 

Thanks for the quick replies

Another option would be to get a CRD. But my 2nd Rubicon was a deal I couldn't refuse. Next JK will be a CRD. Won't even know the tires have been changed.

 

I went from the stock Rubicon BFG KM's in the 255/75r17 size to a Hankook Dynapro in a 285/70r17. There was very little difference in fuel economy and power. The Jeep ran at maybe 100 rpm less on the highway--not even noticeable. I have the stock 4.10 gears. The Jeep did not seem to shift any more often on a 1500 mile trip of varied terrain (flat, hills, and mountain passes). Fuel economy dropped by maybe 1/2 of a mile per gallon. My speedometer read 1mph slow at 65mph (compared to the MyGig navigation), just exactly as it did before the tire change--so no recalibration necessary for me. Acceleration seemed slightly slower, probably due to the heavier weight of the tires.

So overall the change was minimal. If you like how your Jeep drives now, it will drive about the same (assuming you have 4.10 gears). But personally I think the Jeep could use 4.56 gears with the stock 32's. I didn't end up keeping the 33's, because I didn't really like the Hankooks, but I will probably go back to 33's later. I would like to re-gear, but probably won't.

 

I run a 295/70 r17 trail grappler (heavy tire) on my sahara stock gears and it is good to go. Definitely recalibrate the speedo for the shift points though. Mine sucked before my pro-cal straightened it out.

 

If you already have the Rubicon with 4.10 gears, you won't notice that much of a difference to justify $1200-1600 to regear the Jeep. You could go to 4.88's but the cost of regearing vs the 1 mpg loss would not be worth it IMO.