How much do you think my 285's are hurting my MPG's ? I have the smarty jr and I am trying maximize fuel efficiency with price of fuel the way it is !! Would it be worth selling the 285's and going back to 265's ? Thanks Pete

 

I dont know how much in your case, but when I went from 285s to 315s I noticed almost 2 mpg drop overall.

 

A wider contact patch does create more drag. A lot also depends on the tread and rubber composition. An off road or mud tread will create a lot more drag than an all season tread.

 

If you use a 285/70 you will have the width but not the height of the 285/75. That will also help to keep a little extra height but not hurt mileage.

 

Very true. Even with the mild rpm reduction,I lost 1 mpg. going to the "75" size. When I put 285-75-17 Toyo MT's on it cost me another 1.5 mpg.

I wish the tire folks would release a 265-80-17 which would be similiar to a 265-70-19.5. Skinny and tall with a e-rating.

 

^^^^ This!