I need someone with good calculator skills. Here's what i want to do, I have an 06 f150 Scab 4x4 that has the factory 245/70/17 tires. My truck has the heavy duty package, so i have the 4.10 gears. I want to get alittle better fuel milage out of it, getting about 15 mpg now. How tall can i go to see improvement, before i start losing mpg? I'm thinking change in tire size will bring my rpms down to a better level. What do you all think?

 

well wendall,is our tire/ rim expert(IMHO) so hopefully he will chime in for ya....
4.10`s? hmmmmm and thats stock?245/70/17 ?

 

You'll probably start to loose MPG's if you go over a 33 inch tall tire. Also, width has an affect also. If you are keeping your OEM wheels, I'd go with a 285/70-17 (33x11.50) tire.

 

Yep.Thats stock on the heavy duty with the 8' bed

 

Thanks for the info, I was thinking no bigger than a 285. You just verified it.