This is the info I'm looking for. My Nitto TerraGrappler G2's are 35x12.5x20 but they are actually 34.5" diameter. So using the Raptor size tire is a perfect fix for me. Can you please verify that the above size tires are actually in the system for a 2015 and not for 2014 and older trucks only?

Thanks!

 

No longer have access to IDS, however, ... The tire sizes that are possible have not changed from the previous gen' 12 F-150s.
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I calibrated to Raptor size on my 2010 with 35x12.50 KO2's, and was still off by about 3 or 4% (in the direction I didn't want - truck was traveling faster than speedo indicated). I then also dropped two gear ratio sizes in the IDS and now it's 100% accurate.

 

Using GPS my trucks are either 1 or 2 mph fast or slow. I use GPS to calibrate them and drive with the GPS set for miles per hour. Waste of time and money to worry about the speed-o-meter for me.

 

Does messing with the configured gear ratios effect anything else other than the speedometer calc? Anything with the trans?

Thanks!

 

Nope, no problems on my own truck, or any of the other ones we've done it on.

 

I am switching from the stock 265/70R17 to 275/55R20. From what I can find it looks like the over all dimension is only changing from 31.6 to 31.9

Is there any need to that the speedo/transmission calibrated with that small of a change? Or will the added weight cause an issue with the transmission?

 

Nope, you'll have zero trouble with that set up as-is.

 

As others mentioned, our Livernois MyCalibrator tuner will allow us to correct this. However, being ids identifies the vehicle, and loads in a predefined options list, I doubt someone would be able to correct a 2015 this way. Furthering this thought is the fact that we are selling these to dealers so they can correct for aftermarket wheels/tires.

 

Any recommendations for good exhaust other then Gibson? From what I can find Gibson only has them for the 5.0L?