Im wondering how much of a differance my f150 will have if i put a 17 inch rimm and tire on it
It has 16 on her now
My dad is selling his 99 expedition it has nice wranglers on a 17 rim on the truck im hoping to switch thanks

 

depends on the tire size they both have.. if the measurements are the same and only the rim size changes than it will be 1" difference..

 

What about my speed / tack

 

what tire size are on the 16 and on the 17??

 

as long as the tire size on the new rims is the same as the tires you currently have there will be no affect to speedo or tac. if you have a 285/75/16 tire and move to a 285/75/17 tire the only thing that changes is the sidewall height.

 

the 285 in this case would be the width of the tire in millimeters. the 75 means that the sidewalls are 75% the measurement of the tread width (So a 285/75 would be 285 mm wide, and the sidewalls would be 213.75 mm from edge of the rim, to the tread). So a 285/75/R17 will be slightly taller than a 285/75/R16... But not enough to seriously throw off your speedo/odometer... But if you like the 17's better, a good tire shop could tell you the best size tire to put on them if you want to maintain the overall tire size... Hope that helps

 

and the rim width
stock 16" are 7" and 17" are 7.5" i belive

 

true, but rim width on such a small channge probably won't be enough to do anything obvious such as cause the wheels to rub, etc.

 

this might help http://www.miata.net/garage/tirecalc.html

 

yeah wont change dimensions, but the look of the tire, and maybe not even much