How much of a mpg drop can I expect on my 2004 f150 when going from the stock 275's to 35" tires? Right now I average somewhere around 15.5 with city and hwy driving. I'm talking now mods....if you have modded with a programmer/chip/etc how much of a difference did it make?

 

when i went to 35's (non tuned) i dropped to about 13 highway- i then xc2'd the truck, and im right back up around 15-16 mpg thats driving at 80-85 mph highway... if I drop myself to around 70 I can manage near 18 constant. you're in town mpg will dive, as getting those heavyassed suckers (assuming muds) rolling isn't easy- in town i see about 10-11 max

 

All around driving for 70,000 miles, with 33 x 13.5's I get about 15.5. Will report in once I run the 37s, but because they are 13.5 wide, I don't expect much change. It's width and weight that make the difference.

 

When I went to 35's on my truck my in town mileage dropped down about 2mpg. Hwy mileage stayed about the same,dropped my 3.73's down to the 3.40 range. Also lost some pulling power when I tow. A programmer would be wise to have.

 

Keep in mind you cannot get an accurate milage calculation if your speedometer/odometer is not correct because you will actually be traveling more miles than your odometer shows.

 

exactly.... who knows if mine changed. i really dont want to know. especially since gas prices are going back up!