wolfmanii

My JK is 4 door, 6 speed manual, 3.73 gear ratio

With stock 30 inch street tire, I got mileage around 15mpg
Now I am running 35 inch Goodyear MTR tire, mileage drops to merely 11-12 mpg

Planning to regear to either 4.88 or 5.13
Can anybody tell me what mpg will I expect?

If the MPG difference for 4.88 and 5.13 is not that big, I would still prefer 5.13.

wolfmanii

No I did not, but I know the exact distance I travel each day. So I calculated my
MPG based on this knowledge of distance, instead of reading the odometer

SpyD JEEP

how long have u been running your 35's with the 3.73 gears? I want to put on 35's this winter but was afraid of running the larger tires with the smaller gears. u running auto or stick? what diff have u noticed in day to day driving with your 35's

how do you find they run run compared to your stockers?
thanks

any pics???

Steel Rain

I have 35's and am recalibrated and still get 11-13 mpg and have 5:13's. I am getting ready to go to 37's and I am sure the mpg will go down again. MPG is not a big thing to me but bigger tires mean less MPG and that's OK with me.... Good Luck

wolfmanii

wow, 5.13 and you still get only 11-13 mpg.

I just wonder if it is caused by ethanol in gas. My friend has a stock JK in Canada
and he claimed he gets 18 mpg local easily. But my identical stock JK can only get
15mpg. I wonder it is because Canada do not add ethanol to gas?

mirewolf

Ethanol does drop the gas mileage. E85 is about 105 octane, but unless you have a turbo all it will do is eat your fuel lines and gaskets. And without subsides it costs much more than gasoline. But the jeep is a "flying brick," so I am more worried about the fuel lines than mileage.

NH-JK

I forget what it's called but there is a fuel additive... Kinda like a sea foam to help with the ethanol... When ethanol sits in the tank motionless it settles... This is bad... Burns up a lot of 2 stroke motors in snowmobiles. It cant be good for our JK's either...

mirewolf

I have used Seafoam in some other vehicles I have had. It can grab water out of the tank but it is mostly to clean carbon deposits out of the engine.

Menard666

I have a stock '09 Rubicon with the stock tires, so 4.10 gearing and 32" BFG KM1's. I have gotten 14-16 MPG since it was new.

Flip94ta

It's sounds like your right foot might need a recalibration. MPG's are more related to the driver than each detail of the drivetrain. with that being said 10% ethanol in you gas will lower your mpgs, I've noticed 1 mpg loss. AT tires also took about 1 mpg away and the recent cold weather took yet another mpg. E10 gas, as it's officially known as isn't a bad product. It burns CLEANER than 87 octane and saves us from sending 10% more money to the Middle East. Don't run that 105 octane E85 in a jeep, it's not made for it. E10 will varnish the fuel system if left sitting for more than 60 days. So no need for seafoam unless you are doing some sitting.