So is it a myth or do you lose 20% gas mileage when you get larger tires (i.e. 35" or 37")? I wanna go big, but while the size would help off road, i generally am a urban commando and it'd be more for intimidating civics, people, and the occasional weak nuts poser in his "blinged out" h3...:-D

 

your defiantly going to lose some on the miles per gallon but hey ..... its a jeep , did you buy it for the mpg anyways? ......

 

You lose a little...MOSTLY, because you will FORGET that your speedometer is WRONG, and you will drive you BRICK LIKE aerodynamic rig much faster than you used to...and, going faster, in a brick, ALWAYS drops your MPG.

It will LOOK like a giant 20% drop...

1> Because you went a lot faster, using more gas to overccome wind resistance, and flooring it to "Get to hwy spd" except maybe 80 mph instead of 65, etc.

2> Because your ODOMETER is wrong...it will say tou went a lot fewer miles...so, when you fill up...it looks like the tank got you far fewerr miles than it used to.

In reality, after correcting for the above...you might lose a bit...but the larger tire is really essentially just a deeper overdrive....it takes a bit more power to roll the rubber, but a mpg 0r so, not 20%, etc.

 

I just took a trip and calculated my MPG along the way.

With 35" KM2 MT's
Windy conditions the whole trip.
Using GPS for correct mileage and speed.

Fairly flat with some hills, averaging 70-72 MPH: 14.8 MPG
Going through the mountains of VA, around 65 MPH: 13.? I have it in the jeep written down.
I just finished my trip going through Ohio and Indiana...mostly flat, around 72MPH: Will have the answer tomorrow after I fill up

Now if I decreased my speed..lol I would get better mileage also

 

Go big, but get new rims/tires... Get some mudders or some boggers, or something crazy offroad, and keep your stock tires rims, if money allows... SO keep your street tires for the street, and well, you get it... Best of both worlds... IF I had some more cash, that is what I woulda done.. If you only offroad every other weekend, what is twenty minutes for you and a buddy to swap four tires?

 

That sounds pretty close to expected...mountain terrain is murder on mpg...and the JK drops mpg like CRAZY as you go over 50 mph.....like at 50 mph...I get a reading in the low 20's...I go into the 70's...and I an down to the mid teens in a hurry....too much wind resistance to take a JK faster than back road speed, w/o major losses in fuel efficiency.

 

X2...Very true...I am running 35s and after speedo correction, I am averaging17.8 mpg. Pretty good for a brick, I think.

 

my gas mileage went to shit, but I look good at the gas pump which is always a plus.

 

Definitely looking forward to seeing what I got on these flat midwest roads.

I know when I took a trip last year with 35" A/T's I got GREAT gas mileage. But then again we were jeepavanning with a group of at least 7 of us. We took it slow. Around 55-60mpg