just upgraded to 20" fx4 wheels and tires on my 06 xlt 4x2 screw with a 5.4 and 17" steel wheels stock since than my milage has gone from 17 mpg to 15 mpg with no change in route or driving style so my question what can i do to improve my milage would a tuner help i dont think i want to go the regearing route. the tires are taller about 3" taller than my stock tires

 

Did you have the odemeter recalibrated? You are covering more ground with it not being recorded, if you didn't, so your calculation would be off.

 

I agree... have the speedo (PCM) recalibrated for the new tire size and your mileage will be somewhere inline with what you started at.

 

is that a dealership item i guess have them reflash the computer or can i do it with a tuner

 

Well...thats only if the tire diameter was different.....i'm changing from 18's to 20's and the tire size is going to be exactly 31.9 inches for both.....so it doesn't always change.

Tire Size Calculator - tire & wheel plus sizing

try that website and see if theres a difference in rev's per mile...

 

You can do it with a tuner or at the dealer. If you're looking for some more mpg you could go with the tuner, intake and exhaust...but just keep your foot off the throttle. Alot of people wont notice the mpg increase, but they are enjoying their extra power at the same time.

S&B Intake Ford F-150 1997-2007



Alot of people are having good luck with the S&B filter, great quality product.

 

oh ya know i missed the part about 3 inches taller......you need to get your computer recalibrated...thats the major problem....you're really going farther than you think....

 

ok ryan cool web site the stock 17" wheels 692.1 revs per mile the new 20" 652.0 rev per mile overall diameter of stock when new 30.05 20" when new 31.90 it calculated a 5.8% size difference so i guess ford progams each truck depending on what tire package they put on it at the factory now if i have my cpu reflashed would it also change shift point to make up for the larger tires or would it just get the speedo back to the right speed and milage

 

If i'm right, it will fix both problems....