grady

I have read the charts, and I am still wanting more before I drop $1500 bucks for a set of 5 new tires. 2010 JK Unlimited, stock gearing, auto and stock tires. 60% of my driving is highway, 35% city streets, the other 5% is offroad. As it is now, highway driving with the OD on, long hills, the transmission will wear you out downshifting and upshifting. If I jump to 35 inch tires, and quit using the OD, where will I be both in performance and mileage compared to current? Right now I average about 18.8 mpg and would like to keep it around there if at all possible.

Thanks

Steven4est

i run 35's on a 2 door with 3.73 gears and a manual. I currently get 14.8 miles per gallon. Im going to regear to 4.88's soon and then get a procal chip. Ive heard of guys getting 18mpg with all these mods after they added the hypermax chip. The point it its a jeep as long as your getting 12 mpg who cares lol

TEXAZJK

I have an 09 Unlimited and got about your same results stock. 4" RE Superflex kit, 35x12.5 KM2's rear tire carrier and Superchips economy mode and I get around 15.7 no matter my mix of driving.

Tranny will hunt on mild inclines now. I plan to regear in the next month or so which should help the tranny and the MPG improve a bit.

grady

That is what I wanted to hear. Someone with a similar setup, prior to a regear but with a larger tire and what it did. I cant afford to buy tires and regear at the same time. I think regearing to a different gear first would be a waste of fuel if nothing else. 35's it is, then start rat holing money for new gears and someone local to set them up.

Thanks

Sixgun

I'm not sure how your gettin 18 mpg but
my 2010 rubi was get around 17mpg stock. 14 with 4.10 and 34in tires. I put 5.13 in, and the engine is running alot better. It's not down shifting like before. Tranny stays in gear unless on a step hill. ( colorado steep!!) I thought it would run alot higher rpm's but it's not at all what I thought. My MPG is better, back up to 16.5 to 17.5. I live in High altitude, so there is less power in my jk. I 'm glad I went with 5.13. If you go with 4.88 you will be happy, If you go 5.13 you will be even more happier. I don't care at all about MPG since the jeep drives a thousand times better then stock.

joneszj

If the only thing holding you back from the larger tires is the gears, don't hesitate. I've run 35s on my 3.21s for over a year. I've taken it wheeling enough times to know my limitations, especially with the open front and LSD rear. It does just fine on the road, although I never use 6th gear (manual tranny). THe auto might be a little bit less tolerable, but it won't be that bad. For the driving you described, I don't see an issue. The way I see it the longer you have the big tires and poor gearing, the more you will appreciate it when they go in.

P.S. I've had my 5.13s setting in the garage for about 2 months while I am saving to get regeared. Just bought an Aussie locker and new carrier for the front, so as soon as that gets here and I get my new Riddlers, I am making the appointment. I am chomping at the bit...you will be too.

Pluke the 2

Good Question, I had the same in mind.

How does everyone get more then 15+ MPG? is there a secret to driving? I average 14... BRAND New 2010 2 Dr Jk with NO MODS to the engine....

bkw

We have very similar rigs and driving habits. I've got an AT w/ 3.73's (which I'd wager is the same as yours), and I'm getting approximately 13.3MPG with the Flashpack set for 87 tune. Driving characteristics are pretty good with the Flashpack and I really don't feel the need to regear at all.

Whats interesting about the graph below is that I got better MPG's immediately after I replaced the hardtop for the softtop. The rise is probably a combo between weight reduction, I tend to drive slower with the top down, and winter gas.

bkw

I think you'll see that the manual transmission owners tend to have signficiantly better fuel economy than slushbox owners.

myklt8

How many miles are on yours?
Milage and performance improve after about 3K