I'm currently running 285/75R17 KM2's which are 62lbs each and I'm getting about 15-17MPGs.

I'm planning to upgrade to either:
-35's KM2's @ 66lbs each
-285/75R17 Toyo MT's @71lbs each (I would get the 35' but they are 83lbs each)

My question is, how much does tire weight affect MPG? Will an increasing tire weight by 4-9lbs each continue to decrease my fuel efficiency? Anyone have experience moving up in tire size and capturing the difference in MPG?

Thanks in advance!

 

Tread is a bigger factor. I have 315/70rx17 Falkens at 83 lbs a piece and still get 19.5 mpg because of their low rolling resistance tread. The weight is only a factor in mileage if you are starting rolling. Once they are moving they want to keep moving.

 

Which has more rolling resistance? KM2's or Toyo MT's?

I'm guessing KM2's since most reviews give them a lower rating for on-road use compared to Toyo's?

 

MT's and mph really don't go hand in hand. If you want better mileage I'd stick with an AT. A lot of rolling resistance comes from the softness of the tire transferring the motion into flexing and deforming of the tire. A bowling ball rolls better than a soft rubber ball.

The lugs of an MT are softer than the tread on an AT and they absorb energy is the bottom line. The ability of a soft MT lug to create more friction is what gives it traction though so it is a trade off.

 

I know your primarily trying to figure out if the weight difference will cause you to get worse gas mileage. A heavier tire will take more power to get rolling so one would assume it will decrease your gas mileage.

I did the same thing your talking about when I made my first tire purchase. I bought the tires that I thought would allow me to have better MPGs and did not like how they looked. Two months later I sold them for a loss and bought the tires that looked better.

No matter what large tires you put on your JK your not going to get good gas mileage. I would buy what looks best in your opinion or what will perform to your needs. Don't worry about gas mileage. I know that is easy to say.

JMHO

 

Heck, I get 16.5-18 MPG with my 35" Toyos, maybe lower 16's MPG in town...

 

X2

My experience is to get the tire with the grip performance for your needs, and the looks. I've found the MPG deltas to be too insignificant to worry over, JMHO.

 

At a steady speed the tread will make more difference. Getting up to speed the weight will make more difference. How you end up depends on what kind of driving you do.

 

I'm rolling 35's Nitto's trail grappler very heavy an very aggressive I'm getting 18-19 MPGs.. It all how you drive an how you use your JK... I have a 6spd so that helps out a lil too