Reprogramming pcm

[Cody Ray]

Today I had a great conversation with my automatic tranny instructor. He explained that putting larger tires on my Ranger would not only throw off the speedometer but the shift points. What I got from the discussion was that the pcm in my truck should have different tire size options as long as they could have come from the factory. He doesn't do much with Fords so he didn't know if my computer would include tire sizes from the 4wd model. If it does this means I could use a scan tool to reset the tire size to the largest factory tire that comes with the 2001 Ford Ranger Supcab XLT 4wd. That would be 265/75-15 which is plenty big for me. The only piece missing here is if the pcm indeed would have the factory 4wd tire options in my 2wd ranger, does it?

 

[kimcrwbr1]

The correct gears in the rear axle should correct both problems someone here will know the correct gears or get you close enough.

 

[Cody Ray]

I was really hoping to avoid messing with the differential. No adjusting pinion depth and buying new shims please!

 

[srteach]

I have seen the ability to change tire sizes on some programmers for the ranger, so I would assume that function is in the pcm. I cannot confirm, though.

 

[Sasquatch_Ryda]

Yes it is possible to do that. It is mostly for getting your speedo correct. You will need to know the revolutions per mile of the tire you are running to enter it into the PCM.