Going from a 265/65-18 to a 275/70-18 on a '10. Can the dealership reprogram my odometer? I know the bigger tire will require some adjustment.

 

I think that is illegal.

 

The Ford IDS software has limited options for tire sizing. While they may not have that specific size, they might have something that's close.

I suggest you call them. You're looking for something in the 33.2" (uncompressed) range.

 

I am fairly certain, the only sizes they will be able to program that are the closest to your size will be 275/65R18 and 315/70R17. The 275 is a 32.1 and the 315 is 34.4. Those are the closest OEM sizes to your tire, neither of which is really close.

 

so what would my best option be to keep the speedometer close to right?

 

There are programmers out there that will do performance enhancements and at least one for tire size only. They are not cheap, with the performance programmers going to be 300+, while the tire only would be a little less.

 

It kills me to post this, but HyperCrap has a 'speedometer calibrator'. No tuning or performance modifications.

http://www.hypertech.com/products-sp...alibrator.aspx

 

Why does it kill you to post that???

And don't programmers usually void your warranty?

Forgive my ignorance. Just curious

 

Because it's a HyperCrap. Too many lack-of-support horror stories to list here.

Warranty might be void - depends on what fails, the dealer's warranty record (with Ford), and Ford.

 

So when I go to make the purchase, should I not worry about it, and deal with the slight difference in the speedomer reading? Or go with the re-calibration?

 

The factory speedometer is about 2mph fast anyways so your slight change in tire probably corrected it. Get a gps in there and see.

 

If the dash speedometer is accurate, then the odometer will be inaccurate.

I would ask the dealer if they can re-flash with the correct tire size.

If they can't, AND you're not interested in performance tuning, I'd look into the HyperCrap.

I didn't mean to scare you off the HyperCrap speedometer calibrator; the horror stories are related to their performance tuners.