Is there anyway to recalibrate these on my own? Or do I need to take it somewhere to fix it? Its been off ever since bigger tires have been on

 

SCT Tuner should be able to do that, I believe.

 

Only on 99+ truck it can do that. The 97-98 use a interchangable gear on the end of the speed sensor. Its located on the back side of the t-case in the tail housing. Ford racing makes the gears and they are $11 a piece. I cant tell you which one you will need tho.. Also another way around it is buy actually putting gears in the truck..