I'm about to replace my Goodyears this weekend...or next and i want to get the BFGs in a 275/75/R17. Right now i have 265/70/R17s. If i end up getting a taller tire, how do i change out the speedo gear? Is it a part i can just pick up at the dealer or will they have to order it?

 

someone?

 

You have/had the largest diameter stock tire Ford sells. Don't believe Ford has speedo gears for larger than the largest stock size Ford sells for a F150.

 

oh. then a tire shop probably would't have that part either would they? Where do i have to get one at?

 

Don't know if any aftermarket place would have one. You may not be able to get one.

If you get an aftermarket computer chip, they can be programed for any tire size and rear end gear ratio you might have. Your change is not that much, you could live with it, or pay $200 + for a new chip.

 

Since you have a 98, you 'should' be able to swap out the VSS gear. Thing to do is find out how many teeth the stock one has. then drop one tooth for the size tire you are getting. That's just a guess, but it'll be closer then it is now.

I had to drop one tooth on my gear when I went from a 235/70/16 to a 265/75/16. That was about 2" taller then stock. I had a 20 tooth gear, so I put in a 19 tooth gear and it worked out just right.

 

yeah, i thought on the '98s that the VSS gear was right by the tranny and you could just swap it out.

 

Yes, Dan you can ... but when you call the dealer, ask them if they have a speedo gear for tires larger than they sell. I doubt it, but you can ask.

 

Ahh, forget it. They don't make BFGs in a 75/R17 anyways