I have a 5.0 2013 XLT SCREW. I recently swapped my wheels and tires to 275/65r20(A little more than 34" compared to stock 32") which messed up my speedometer by about 4 mph. I know the tuners that are out there will allow me to recalibrate my speedo but I do not want to tune my truck because of possible warranty issues. I have replaced my stock exhaust with a Roush catback and plan on installing there intake at a later date. Other than the exhaust, intake and wheels I do not plan on modifying the performance of the vehicle.


My question is this. It looks like the stock Raptor tire size is pretty close. See pic below. If I were to take it to the dealer to get it calibrated to the raptor size, would that also help me as far as mpg like the aftermarket tunes do? Is there anything else that I need to consider with going to the dealer as opposed to a aftermarket tune? Will an aftermarket tune give me more than just increased performance.

 

Mine came stock with 275/55 20 - I would love to move up to a 275/65 20.

Did you have to level or lift your truck for these to fit? Any other issues besides the speedo being off?

Very interested to know and hear replies from others as well.

 

The diameter of my tires is very close to Raptor tire size. My dealer told me he couldn't calibrate my speedo for that size. He said that he could only calibrate my FX4 for the 275/55/20 or the 275/65/18 that were options on an FX4. Not sure if that is 100% true or not. I finally got mine calibrated with my Livernois tuner.

 

2.5" Rough Country level. I had to trim a tiny bit.

 

...will adjust for the new size.

I switched from the stock 275/55-20 to the 275/65-20 using the Hypertech unit to make the correction.

Northlight

 

That's still a tune. Isn't it? Is it detectable by the dealer as a flash?

 

I was hoping to do this same thing. Will be getting 275/65r20 and hoping to calibrate to raptor size. Can anyone confirm this being done and their results?

 

Went thru this with my F250. The dealer is only able to scroll thru sizes that were available on YOUR truck from the factory. You don't have a Raptor so the Raptor size tires are not in there to select.

Stupid, I agree, but the way it is. You may get close but not exact. (From the dealer)

 

just get a tuner and you can dial it in perfect. no going back to the dealer just to kinda get it close.

When I put my tires on i was way off. Got a SCT and put in the correct tire RPM and was still off by a couple mph. Dialed it back 20 RPMs and now I'm dead on GPS and Radar Signs.