How will 33" tires affect my gas mileage?

i just went from stock tires to 285/65R18 and my gas mileage went from 19-20 to 15-16. Power loss isn't much and stock gears work fine but now i'm thinking of going to 4:10 gears to get back a couple mpgs

 

I have 33X12.5 on my 4 cyl, 4.10 gears, and I get 17/21mpg. That is if I baby it and keep it around 1500-2000rpm's.

I plan on going to either a 32 or a 31 to get the power/mpg back.

 

I've got a 6" lift with 285/75/r16, I'm at 13.8 mpg at best and a little sluggish up the grade. Stock gears too.... Hope this helps....let me know if you have any other questions...

 

Dang I have an 01 2.7 4cylinder with a 3inch lift and 265/70/16. I am going to say that I usually get between 16 and 19 mpg. I have had it just about a year and don't think I have seen 300miles for a tank.