Hey guys, I posting this for a friend of mine. He has an 03`F-350 standard cab p/u. He wants to know what`s the biggest tires he can put on the factory stock wheels without adjusting the speedo. Does any one know?

 

ANY increase in tire size will result in an inaccurate speedometer, and a need to recalibrate it.

 

DId you ever get an answer to your question - I have the same one for my f250 screw

 

Any change in tire size from stock will affect the speedo. Goto this website and put in your tire sizes and it will tell you actual mph and what the speedo will say for different tire sizes along with other dimensions in understandable measurements, http://www.miata.net/garage/tirecalc.html

 

I put 285's on mine and by GPS it's about as dead on as you can get. They add about 1/2" to the height.

 

How do you change the Speedo???

 

You have to have the speedo re-programmed by dealer (big pain) or by a 4x4 shop - easy.

runnert

 

Didn't some require changing a small gear in the rear end? Not saying that I am right or anything, just making sure.

 

any upsize in tire will set off the speedo but the biggest tire size that you can fit on a super duty are 315/75R16's

 

just put 38" tires under my super duty and the speedo seems to be around 14% off track.. i have 4:10 gears under,


the 4:10 gears did the job in my old 150 with 35"tires...