I have an '04 F-150 with 20" pro comp rims and 35" dick cepek tires. I was reading the manual for the Evolution programmer that I just installed and am trying to figure out how to adjust my speed for the tires. I was also wondering if I need to fiddle with the gear ratio. Thanks for the help!

 

i should have the correct ratio in it. in the manual it has a little chart that will show you what number to put in for your tire. it has an exact number for 35s.

 

yeah the manual has a number to put in for your tire size but you need to subract about 2-4% of that number from it for the squish factor. that'll make it more accurate.